NAME¶
x11vnc - allow VNC connections to real X11 displays
version: 0.9.13, lastmod: 2011-08-10
SYNOPSIS¶
x11vnc [OPTION]...
DESCRIPTION¶
Typical usage is:
- Run this command in a shell on the remote machine
"far-host" with X session you wish to view:
- x11vnc -display :0
- Then run this in another window on the machine you are
sitting at:
- vncviewer far-host:0
Once x11vnc establishes connections with the X11 server and starts listening as
a VNC server it will print out a string: PORT=XXXX where XXXX is typically
5900 (the default VNC server port). One would next run something like this on
the local machine: "vncviewer hostname:N" where "hostname"
is the name of the machine running x11vnc and N is XXXX - 5900, i.e. usually
"vncviewer hostname:0".
By default x11vnc will not allow the screen to be shared and it will exit as
soon as the client disconnects. See
-shared and
-forever below
to override these protections. See the FAQ for details how to tunnel the VNC
connection through an encrypted channel such as
ssh(1). In brief:
- ssh -t -L 5900:localhost:5900 far-host
'x11vnc -localhost -display :0'
% vncviewer -encodings 'copyrect tight zrle hextile' localhost:0
Also, use of a VNC password (-rfbauth or
-passwdfile) is strongly
recommended.
For additional info see:
http://www.karlrunge.com/x11vnc/ and
http://www.karlrunge.com/x11vnc/faq.html
Config file support: if the file $HOME/.x11vncrc exists then each line in it is
treated as a single command line option. Disable with
-norc. For each
option name, the leading character "-" is not required. E.g. a line
that is either "forever" or "
-forever" may be used
and are equivalent. Likewise "wait 100" or "
-wait
100" are acceptable and equivalent lines. The "#"
character comments out to the end of the line in the usual way (backslash it
for a literal). Leading and trailing whitespace is trimmed off. Lines may be
continued with a "\" as the last character of a line (it becomes a
space character).
OPTIONS¶
-display disp
- X11 server display to connect to, usually :0. The X server
process must be running on same machine and support MIT-SHM. Equivalent to
setting the DISPLAY environment variable to disp.
- See the description below of the "-display
WAIT:..." extensions, where alias " -find"
will find the user's display automatically, and "
-create" will create a Xvfb session if no session is
found.
-auth file
- Set the X authority file to be file, equivalent to
setting the XAUTHORITY environment variable to file before startup.
Same as -xauth file. See Xsecurity(7) , xauth(1) man
pages for more info.
- Use '-auth guess' to have x11vnc use its -findauth
mechanism (described below) to try to guess the XAUTHORITY filename and
use it.
- XDM/GDM/KDM: if you are running x11vnc as root and want to
find the XAUTHORITY before anyone has logged into an X session yet, use:
x11vnc -env FD_XDM=1 -auth guess ... (This will also find
the XAUTHORITY if a user is already logged into the X session.) When
running as root, FD_XDM=1 will be tried if the initial -auth guess
fails.
-N
- If the X display is :N, try to set the VNC display to also
be :N This just sets the -rfbport option to 5900+N The program will
exit immediately if that port is not available. The -N option only
works with normal -display usage, e.g. :0 or :8, -N is
ignored in the -display WAIT:..., -create, -find,
-svc, -redirect, etc modes.
-autoport n
- Automatically probe for a free VNC port starting at n. The
default is to start probing at 5900. Use this to stay away from other VNC
servers near 5900.
-rfbport str
- The VNC port to listen on (a LibVNCServer option), e.g.
5900, 5901, etc. If specified as " -rfbport
PROMPT" then the x11vnc -gui is used to prompt the user
to enter the port number.
-6
- IPv6 listening support. In addition to IPv4, the IPv6
address is listened on for incoming connections. The same port number as
IPv4 is used.
- NOTE: This x11vnc binary was compiled to have the
"-6" IPv6 listening mode ENABLED by default (CPPFLAGS
-DX11VNC_LISTEN6=1). So to disable IPv6 listening mode you MUST
supply the " -no6" option (see below.)
- The "-6" mode works for both normal connections
and -ssl encrypted ones. Nearly everything is supported for the
IPv6 case, but there are a few exceptions. See -stunnel for its
IPv6 support.
- Currently, for absolutely everything to work correctly the
machine may need to have some IPv4 support, at the least for the loopback
interface. However, for nearly all usage modes no IPv4 support is
required. See -nopiv4.
- If you have trouble compiling or running in IPv6 mode, set
-DX11VNC_IPV6=0 in CPPFLAGS when configuring to disable IPv6
support.
-no6
- Disable IPv6 listening support (only useful if the
"-6" mode is compiled in to be the default; see the
X11VNC_LISTEN6 description above under "-6".)
-noipv6
- Do not try to use IPv6 for any listening or connecting
sockets. This includes both the listening service port(s) and outgoing
connections from -connect, -connect_or_exit, or
-proxy. Use this if you are having problems due to IPv6.
-noipv4
- Do not try to use IPv4 for any listening or connecting
sockets. This is mainly for exploring the behavior of x11vnc on an
IPv6-only system, but may have other uses.
-reopen
- If the X server connection is disconnected, try to reopen
the X display (up to one time.) This is of use for display managers like
GDM (KillInitClients option) that kill x11vnc just after the user logs
into the X session. Note: the reopened state may be unstable. Set
X11VNC_REOPEN_DISPLAY=n to reopen n times and set X11VNC_REOPEN_SLEEP_MAX
to the number of seconds, default 10, to keep trying to reopen the display
(once per second.)
- Update: as of 0.9.9, x11vnc tries to automatically avoid
being killed by the display manager by delaying creating windows or using
XFIXES. So you shouldn't need to use KillInitClients=false as long as you
log in quickly enough (within 45 seconds of connecting.) You can disable
this by setting X11VNC_AVOID_WINDOWS=never. You can also set it to the
number of seconds to delay.
-reflect host:N
- Instead of connecting to and polling an X display, connect
to the remote VNC server host:N and be a reflector/repeater for it. This
is useful for trying to manage the case of many simultaneous VNC viewers
(e.g. classroom broadcasting) where, e.g. you put a repeater on each
network switch, etc, to improve performance by distributing the load and
network traffic. Implies -shared (use -noshared as a later
option to disable). See the discussion below under -rawfb
vnc:host:N for more details.
-id windowid
- Show the X window corresponding to windowid not the
entire display. New windows like popup menus, transient toplevels, etc,
may not be seen or may be clipped. Disabling SaveUnders or BackingStore in
the X server may help show them. x11vnc may crash if the window is
initially partially obscured, changes size, is iconified, etc. Some steps
are taken to avoid this and the -xrandr mechanism is used to track
resizes. Use xwininfo(1) to get the window id, or use "
-id pick" to have x11vnc run xwininfo(1) for you
and extract the id. The -id option is useful for exporting very
simple applications (e.g. the current view on a webcam).
-sid windowid
- As -id, but instead of using the window directly it
shifts a root view to it: this shows SaveUnders menus, etc, although they
will be clipped if they extend beyond the window.
-tag str
- This option is ignored, but allows you to specify a unique
string on the x11vnc command line, for example " -tag
test34934z", this could enable a reliable way to identify
different x11vnc processes via their command lines (see ps(1) ,
pgrep(1) , and pkill(1) and /proc/PID/cmdline.)
-appshare
- Simple application sharing based on the -id/-sid
mechanism. Every new toplevel window that the application creates induces
a new viewer window via a reverse connection. The -id/-sid and
-connect options are required. Run 'x11vnc -appshare
-help' for more info.
-clip WxH+X+Y
- Only show the sub-region of the full display that
corresponds to the rectangle geometry with size WxH and offset +X+Y. The
VNC display has size WxH (i.e. smaller than the full display). This also
works for -id/-sid mode where the offset is relative to the upper
left corner of the selected window. An example use of this option would be
to split a large (e.g. Xinerama) display into two parts to be accessed via
separate viewers by running a separate x11vnc on each part.
- Use '-clip xinerama0' to clip to the first xinerama
sub-screen (if xinerama is active). xinerama1 for the 2nd sub-screen, etc.
This way you don't need to figure out the WxH+X+Y of the desired xinerama
sub-screen. screens are sorted in increasing distance from the (0,0)
origin (I.e. not the Xserver's order).
-flashcmap
- In 8bpp indexed color, let the installed colormap flash as
the pointer moves from window to window (slow). Also try the -8to24
option to avoid flash altogether.
-shiftcmap n
- Rare problem, but some 8bpp displays use less than 256
colorcells (e.g. 16-color grayscale, perhaps the other bits are used for
double buffering) *and* also need to shift the pixels values away from 0,
.., ncells. n indicates the shift to be applied to the pixel
values. To see the pixel values set DEBUG_CMAP=1 to print out a colormap
histogram. Example: -shiftcmap 240
-notruecolor
- For 8bpp displays, force indexed color (i.e. a colormap)
even if it looks like 8bpp TrueColor (rare problem).
-advertise_truecolor
- If the X11 display is indexed color, lie to clients when
they first connect by telling them it is truecolor. To workaround RealVNC:
inPF has colourMap but not 8bpp Use '-advertise_truecolor reset' to reset
client fb too.
-visual n
- This option probably does not do what you think. It simply
*forces* the visual used for the framebuffer; this may be a bad thing...
(e.g. messes up colors or cause a crash). It is useful for testing and for
some workarounds. n may be a decimal number, or 0x hex. Run
xdpyinfo(1) for the values. One may also use "TrueColor",
etc. see <X11/X.h> for a list. If the string ends in ":m"
then for better or for worse the visual depth is forced to be m. You may
want to use -noshm when using this option (so XGetImage may
automatically translate the pixel data).
-overlay
- Handle multiple depth visuals on one screen, e.g. 8+24 and
24+8 overlay visuals (the 32 bits per pixel are packed with 8 for
PseudoColor and 24 for TrueColor).
- Currently -overlay only works on Solaris via
XReadScreen(3X11) and IRIX using XReadDisplay(3). On Solaris
there is a problem with image "bleeding" around transient popup
menus (but not for the menu itself): a workaround is to disable SaveUnders
by passing the " -su" argument to Xsun (in
/etc/dt/config/Xservers).
- Use -overlay as a workaround for situations like
these: Some legacy applications require the default visual to be 8bpp
(8+24), or they will use 8bpp PseudoColor even when the default visual is
depth 24 TrueColor (24+8). In these cases colors in some windows will be
incorrect in x11vnc unless -overlay is used. Another use of
-overlay is to enable showing the exact mouse cursor shape (details
below).
- Under -overlay, performance will be somewhat slower
due to the extra image transformations required. For optimal performance
do not use -overlay, but rather configure the X server so that the
default visual is depth 24 TrueColor and try to have all apps use that
visual (e.g. some apps have -use24 or -visual options).
-overlay_nocursor
- Sets -overlay, but does not try to draw the exact
mouse cursor shape using the overlay mechanism.
-8to24 [opts]
- Try this option if -overlay is not supported on your
OS, and you have a legacy 8bpp app that you want to view on a multi-depth
display with default depth 24 (and is 32 bpp) OR have a default depth 8
display with depth 24 overlay windows for some apps. This option may not
work on all X servers and hardware (tested on XFree86/Xorg mga driver and
Xsun). The "opts" string is not required and is described
below.
- This mode enables a hack where x11vnc monitors windows
within 3 levels from the root window. If it finds any that are 8bpp it
extracts the indexed color pixel values using XGetImage() and then applies
a transformation using the colormap(s) to create TrueColor RGB values that
it in turn inserts into bits 1-24 of the framebuffer. This creates a depth
24 "view" of the display that is then exported via VNC.
- Conversely, for default depth 8 displays, the depth 24
regions are read by XGetImage() and everything is transformed and inserted
into a depth 24 TrueColor framebuffer.
- Note that even if there are *no* depth 24 visuals or
windows (i.e. pure 8bpp), this mode is potentially an improvement over
-flashcmap because it avoids the flashing and shows each window in
the correct color.
- This method works OK, but may still have bugs and it does
hog resources. If there are multiple 8bpp windows using different
colormaps, one may have to iconify all but one for the colors to be
correct.
- There may be painting errors for clipping and switching
between windows of depths 8 and 24. Heuristics are applied to try to
minimize the painting errors. One can also press 3 Alt_L's in a row to
refresh the screen if the error does not repair itself. Also the option
-fixscreen 8=3.0 or -fixscreen V=3.0 may be used to
periodically refresh the screen at the cost of bandwidth (every 3 sec for
this example).
- The [opts] string can contain the following settings.
Multiple settings are separated by commas.
- For for some X servers with default depth 24 a speedup may
be achieved via the option "nogetimage". This enables a scheme
were XGetImage() is not used to retrieve the 8bpp data. Instead, it
assumes that the 8bpp data is in bits 25-32 of the 32bit X pixels. There
is no requirement that the X server should put the data there for our poll
requests, but some do and so the extra steps to retrieve it can be
skipped. Tested with mga driver with XFree86/Xorg. For the default depth 8
case this option is ignored.
- To adjust how often XGetImage() is used to poll the
non-default visual regions for changes, use the option "poll=t"
where "t" is a floating point time. (default: 0.05)
- Setting the option "level2" will limit the search
for non-default visual windows to two levels from the root window. Do this
on slow machines where you know the window manager only imposes one extra
window between the app window and the root window.
- Also for very slow machines use "cachewin=t"
where t is a floating point amount of time to cache XGetWindowAttributes
results. E.g. cachewin=5.0. This may lead to the windows being unnoticed
for this amount of time when deiconifying, painting errors, etc.
- While testing on a very old SS20 these options gave
tolerable response: -8to24 poll=0.2,cachewin=5.0. For this machine
-overlay is supported and gives better response.
- Debugging for this mode can be enabled by setting
"dbg=1", "dbg=2", or "dbg=3".
-24to32
- Very rare problem: if the framebuffer (X display or
-rawfb) is 24bpp instead of the usual 32bpp, then dynamically
transform the pixels to 32bpp. This will be slower, but can be used to
work around problems where VNC viewers cannot handle 24bpp (e.g.
"main: setPF: not 8, 16 or 32 bpp?"). See the FAQ for more
info.
- In the case of -rawfb mode, the pixels are directly
modified by inserting a 0 byte to pad them out to 32bpp. For X displays, a
kludge is done that is equivalent to " -noshm
-visual TrueColor:32". (If better performance is needed
for the latter, feel free to ask).
-scale fraction
- Scale the framebuffer by factor fraction. Values
less than 1 shrink the fb, larger ones expand it. Note: the image may not
be sharp and response may be slower. If fraction contains a decimal
point "." it is taken as a floating point number, alternatively
the notation "m/n" may be used to denote fractions exactly, e.g.
-scale 2/3
- To scale asymmetrically in the horizontal and vertical
directions, specify a WxH geometry to stretch to: e.g. '-scale 1024x768',
or also '-scale 0.9x0.75'
- Scaling Options: can be added after fraction via
":", to supply multiple ":" options use commas. If you
just want a quick, rough scaling without blending, append ":nb"
to fraction (e.g. -scale 1/3:nb). No blending is the default
for 8bpp indexed color, to force blending for this case use
":fb".
- To disable -scrollcopyrect and -wirecopyrect
under -scale use ":nocr". If you need to to enable them
use ":cr" or specify them explicitly on the command line. If a
slow link is detected, ":nocr" may be applied automatically.
Default: :cr
- More esoteric options: for compatibility with vncviewers
the scaled width is adjusted to be a multiple of 4: to disable this use
":n4". ":in" use interpolation scheme even when
shrinking, ":pad" pad scaled width and height to be multiples of
scaling denominator (e.g. 3 for 2/3).
-geometry WxH
- Same as -scale WxH
-scale_cursor frac
- By default if -scale is supplied the cursor shape is
scaled by the same factor. Depending on your usage, you may want to scale
the cursor independently of the screen or not at all. If you specify
-scale_cursor the cursor will be scaled by that factor. When using
-scale mode to keep the cursor at its "natural" size use
" -scale_cursor 1". Most of the ":"
scaling options apply here as well.
-viewonly
- All VNC clients can only watch (default off).
-shared
- VNC display is shared, i.e. more than one viewer can
connect at the same time (default off).
-once
- Exit after the first successfully connected viewer
disconnects, opposite of -forever. This is the Default.
-forever
- Keep listening for more connections rather than exiting as
soon as the first client(s) disconnect. Same as -many
- To get the standard non-shared VNC behavior where when a
new VNC client connects the existing VNC client is dropped use:
-nevershared -forever This method can also be used to guard
against hung TCP connections that do not go away.
-loop
- Create an outer loop restarting the x11vnc process whenever
it terminates. -bg and -inetd are ignored in this mode
(however see -loopbg below).
- Useful for continuing even if the X server terminates and
restarts (at that moment the process will need permission to reconnect to
the new X server of course).
- Use, e.g., -loop100 to sleep 100 millisecs between
restarts, etc. Default is 2000ms (i.e. 2 secs) Use, e.g. -loop300,5
to sleep 300 ms and only loop 5 times.
- If -loopbg (plus any numbers) is specified instead,
the " -bg" option is implied and the mode approximates
inetd(8) usage to some degree. In this case when it goes into the
background any listening sockets (i.e. ports 5900, 5800) are closed, so
the next one in the loop can use them. This mode will only be of use if a
VNC client (the only client for that process) is already connected before
the process goes into the background, for example, usage of
-display WAIT:.., -svc, and -connect can make use of
this "poor man's" inetd mode. The default wait time is 500ms in
this mode. This usage could use useful: -svc -bg
-loopbg
-timeout n
- Exit unless a client connects within the first n seconds
after startup.
- If there have been no connection attempts after n seconds
x11vnc exits immediately. If a client is trying to connect but has not
progressed to the normal operating state, x11vnc gives it a few more
seconds to finish and exits if it does not make it to the normal
state.
- For reverse connections via -connect or
-connect_or_exit a timeout of n seconds will be set for all reverse
connects. If the connect timeout alarm goes off, x11vnc will exit
immediately.
-sleepin n
- At startup sleep n seconds before proceeding (e.g. to allow
redirs and listening clients to start up)
- If a range is given: '-sleepin min-max', a random value
between min and max is slept. E.g. '-sleepin 0-20' and ´-sleepin
10-30'. Floats are allowed too.
-inetd
- Launched by inetd(8): stdio instead of listening
socket. Note: if you are not redirecting stderr to a log file (via shell
2> or -o option) you MUST also specify the -q option,
otherwise the stderr goes to the viewer which will cause it to abort.
Specifying both -inetd and -q and no -o will
automatically close the stderr.
- If the libvncserver used supports non AF_INET sockets (the
one bundled in x11vnc 0.9.13 and later does), then -inetd mode can
be used for a raw stdio pipe. For example, using the SSVNC viewer exec=...
mechanism:
- ssvnc -viewer exec="ssh -tt -e
none user@host \ ´x11vnc -inetd -o log.txt
-display :0'"
- where the long cmdline has been split. In the above the
only TCP connection is that of the ssh connection. There is no port
redirection (-L), etc.; raw stdio is used on both sides of the ssh. In
some cases the -tt option is not needed.
-tightfilexfer
- Enable the TightVNC file transfer extension. Note that that
when the -viewonly option is supplied all file transfers are
disabled. Also clients that log in viewonly cannot transfer files.
However, if the remote control mechanism is used to change the global or
per-client viewonly state the filetransfer permissions will NOT
change.
- IMPORTANT: please understand if -tightfilexfer is
specified and you run x11vnc as root for, say, inetd or display manager
(gdm, kdm, ...) access and you do not have it switch users via the
-users option, then VNC Viewers that connect are able to do
filetransfer reads and writes as *root*.
- Also, tightfilexfer is disabled in -unixpw
mode.
-ultrafilexfer
- Note: to enable UltraVNC filetransfer and to get it to work
you probably need to supply these LibVNCServer options: "
-rfbversion 3.6 -permitfiletransfer" "
-ultrafilexfer" is an alias for this combination.
- IMPORTANT: please understand if -ultrafilexfer is
specified and you run x11vnc as root for, say, inetd or display manager
(gdm, kdm, ...) access and you do not have it switch users via the
-users option, then VNC Viewers that connect are able to do
filetransfer reads and writes as *root*.
- Note that sadly you cannot do both -tightfilexfer
and -ultrafilexfer at the same time because the latter requires
setting the version to 3.6 and tightvnc will not do filetransfer when it
sees that version number.
-http
- Instead of using -httpdir (see below) to specify
where the Java vncviewer applet is, have x11vnc try to *guess* where the
directory is by looking relative to the program location and in standard
locations (/usr/local/share/x11vnc/classes, etc). Under -ssl or
-stunnel the ssl classes subdirectory is sought.
-http_ssl
- As -http, but force lookup for ssl classes
subdir.
- Note that for HTTPS, single-port Java applet delivery you
can set X11VNC_HTTPS_DOWNLOAD_WAIT_TIME to the max number of seconds to
wait for the applet download to finish. The default is 15.
-avahi
- Use the Avahi/mDNS ZeroConf protocol to advertise this VNC
server to the local network. (Related terms: Rendezvous, Bonjour).
Depending on your setup, you may need to start avahi-daemon and open udp
port 5353 in your firewall.
- You can set X11VNC_AVAHI_NAME, X11VNC_AVAHI_HOST, and/or
X11VNC_AVAHI_PORT environment variables to override the default values.
For example: -env X11VNC_AVAHI_NAME=wally
- If the avahi API cannot be found at build time, a helper
program like avahi- publish(1) or dns- sd(1) will be
tried
-mdns
- Same as -avahi.
-zeroconf
- Same as -avahi.
-connect string
- For use with "vncviewer -listen" reverse
connections. If string has the form "host" or
"host:port" the connection is made once at startup.
- Use commas for a list of host's and host:port's. E.g.
-connect host1,host2 or host1:0,host2:5678. Note that to reverse
connect to multiple hosts at the same time you will likely need to also
supply: -shared
- Note that unlike most vnc servers, x11vnc will require a
password for reverse as well as for forward connections. (provided
password auth has been enabled, -rfbauth, etc) If you do not want
to require a password for reverse connections set
X11VNC_REVERSE_CONNECTION_NO_AUTH=1 in your environment before starting
x11vnc.
- If string contains "/" it is instead
interpreted as a file to periodically check for new hosts. The first line
is read and then the file is truncated. Be careful about the location of
this file if x11vnc is running as root (e.g. via gdm(1) ,
etc).
- Repeater mode: Some services provide an intermediate
"vnc repeater": http://www.uvnc.com/addons/repeater.html (and
also http://koti.mbnet.fi/jtko/ for linux port) that acts as a
proxy/gateway. Modes like these require an initial string to be sent for
the reverse connection before the VNC protocol is started. Here are the
ways to do this:
- -connect pre=some_string+host:port -connect
pre128=some_string+host:port -connect repeater=ID:1234+host:port
-connect repeater=23.45.67.89::5501+host:port
- SSVNC notation is also supported:
- -connect repeater://host:port+ID:1234
- As with normal -connect usage, if the repeater port
is not supplied 5500 is assumed.
- The basic idea is between the special tag, e.g.
"pre=" and "+" is the pre-string to be sent. Note that
in this case host:port is the repeater server, NOT the vnc viewer. Somehow
the pre-string tells the repeater server how to find the vnc viewer and
connect you to it.
- In the case pre=some_string+host:port,
"some_string" is simply sent. In the case
preNNN=some_string+host:port "some_string" is sent in a null
padded buffer of length NNN. repeater= is the same as pre250=, this is the
ultravnc repeater buffer size.
- Strings like "\n" and "\r", etc. are
expanded to newline and carriage return. "\c" is expanded to
"," since the connect string is comma separated.
- See also the -proxy option below for additional ways
to plumb reverse connections.
- Reverse SSL: using -connect in -ssl mode
makes x11vnc act as an SSL client (initiates SSL connection) rather than
an SSL server. The idea is x11vnc might be connecting to stunnel on the
viewer side with the viewer in listening mode. If you do not want this
behavior, use -env X11VNC_DISABLE_SSL_CLIENT_MODE=1. With this the
viewer side can act as the SSL client as it normally does for forward
connections.
- Reverse SSL Repeater mode: This will work, but note that if
the VNC Client does any sort of a 'Fetch Cert' action before connecting,
then the Repeater will likely drop the connection and both sides will need
to restart. Consider the use of -connect_or_exit and
-loop300,2 to have x11vnc reconnect once to the repeater after the
fetch. You will probably also want to supply -sslonly to avoid
x11vnc thinking the delay in response means the connection is VeNCrypt.
The env var X11VNC_DISABLE_SSL_CLIENT_MODE=1 discussed above may also be
useful (i.e. the viewer can do a forward connection as it normally
does.)
- IPv6: as of x11vnc 0.9.10 the -connect option should
connect to IPv6 hosts properly. If there are problems you can disable IPv6
by setting -DX11VNC_IPV6=0 in CPPFLAGS when configuring. If there
problems connecting to IPv6 hosts consider a relay like the included
inet6to4 script or the -proxy option.
-connect_or_exit str
- As with -connect, except if none of the reverse
connections succeed, then x11vnc shuts down immediately
- An easier to type alias for this option is '-coe'
- By the way, if you do not want x11vnc to listen on ANY
interface use -rfbport 0 which is handy for the
-connect_or_exit mode.
-proxy string
- Use proxy in string (e.g. host:port) as a proxy for making
reverse connections (-connect or -connect_or_exit options).
- Web proxies are supported, but note by default most of them
only support destination connections to ports 443 or 563, so this might
not be very useful (the viewer would need to listen on that port or the
router would have to do a port redirection).
- A web proxy may be specified by either
"host:port" or "http://host:port" (the port is
required even if it is the common choices 80 or 8080)
- SOCKS4, SOCKS4a, and SOCKS5 are also supported. SOCKS
proxies normally do not have restrictions on the destination port
number.
- Use a format like this: socks://host:port or
socks5://host:port. Note that ssh -D does not support SOCKS4a, so
use socks5://. For socks:// SOCKS4 is used on a numerical IP and
"localhost", otherwise SOCKS4a is used (and so the proxy tries
to do the DNS lookup).
- An experimental mode is "-proxy
http://host:port/..." Note the "/" after the port
that distinguishes it from a normal web proxy. The port must be supplied
even if it is the default 80. For this mode a GET is done to the supplied
URL with the string host=H&port=P appended. H and P will be the
-connect reverse connect host and port. Use the string
"__END__" to disable the appending. The basic idea here is that
maybe some cgi script provides the actual viewer hookup and tunnelling.
How to actually achieve this within cgi, php, etc. is not clear... A
custom web server or apache module would be straight-forward.
- Another experimental mode is "-proxy
ssh://user@host" in which case a SSH tunnel is used for the
proxying. "user@" is not needed unless your unix username is
different on "host". For a non-standard SSH port use
ssh://user@host:port. If proxies are chained (see next paragraph) then the
ssh one must be the first one. If ssh-agent is not active, then the ssh
password needs to be entered in the terminal where x11vnc is running.
Examples:
- -connect localhost:0 -proxy
ssh://me@friends-pc:2222
- -connect snoopy:0 -proxy
ssh://ssh.company.com
- Multiple proxies may be chained together in case one needs
to ricochet off of a number of hosts to finally reach the VNC viewer. Up
to 3 may be chained, separate them by commas in the order they are to be
connected to. E.g.: http://host1:port1,socks5://host2:port2 or three like:
first,second,third
- IPv6: as of x11vnc 0.9.10 the -proxy option should
connect to IPv6 hosts properly. If there are problems you can disable IPv6
by setting -DX11VNC_IPV6=0 in CPPFLAGS when configuring. If there
problems connecting to IPv6 hosts consider a relay like the included
inet6to4 script.
-vncconnect, -novncconnect
- Monitor the VNC_CONNECT X property set by the standard VNC
program vncconnect(1). When the property is set to "host"
or "host:port" establish a reverse connection. Using
xprop(1) instead of vncconnect may work (see the FAQ). The
-remote control mechanism uses X11VNC_REMOTE channel, and this
option disables/enables it as well. Default: -vncconnect
- To use different names for these X11 properties (e.g. to
have separate communication channels for multiple x11vnc's on the same
display) set the VNC_CONNECT or X11VNC_REMOTE env. vars. to the string you
want, for example: -env X11VNC_REMOTE=X11VNC_REMOTE_12345 Both
sides of the channel must use the same unique name. The same can be done
for the internal X11VNC_TICKER property (heartbeat and timestamp) if
desired.
-allow host1[,host2..]
- Only allow client connections from hosts matching the comma
separated list of hostnames or IP addresses. By ending in a ".",
it can also be a numerical IP prefix, e.g. "192.168.100." to
match a simple subnet, for more control build LibVNCServer with libwrap
support (See the FAQ). If the list contains a "/" it instead is
a interpreted as a file containing addresses or prefixes that is re-read
each time a new client connects. Lines can be commented out with the
"#" character in the usual way.
- -allow applies in -ssl mode, but not in
-stunnel mode.
- IPv6: as of x11vnc 0.9.10 a host can be specified in IPv6
numerical format, e.g. 2001:4860:b009::93
- Env. vars: Set -env X11VNC_DEBUG_ACCESS=1 to print
out debugging info during the check_access() call. Set -env
X11VNC_ALLOW_FULLMATCH=1 to force a full string match, that is, no subnet
"." matching will be performed.
- Unix sockets: if -unixsock is being used and you
want to limit TCP access also you must also include the path to the unix
socket prefixed with "unix=" in the allow list, e.g.:
-allow 192.168.100.3,unix=/tmp/mysock If the socket is not a named
one, e.g. created via socketpair(2) with -inetd, then you
must supply the generic name x11vnc gives to it, e.g. -allow
192.168.100.3,UNNAMED_AF_UNIX In both cases it must be an exact string
match to be allowed to connect. Note that since you completely control
these local non-TCP access methods by file system permissions, etc., it is
not useful to guard against them with -allow, however you still
need to have them in the allow list to let them connect.
-localhost
- Basically the same as "-allow
127.0.0.1".
- Note: if you want to restrict which network interface
x11vnc listens on, see the -listen option below. E.g. "
-listen localhost" or "-listen
192.168.3.21". As a special case, the option "
-localhost" implies " -listen
localhost".
- A rare case, but for non-localhost -listen usage, if
you use the remote control mechanism (-R) to change the -listen
interface you may need to manually adjust the -allow list (and vice
versa) to avoid situations where no connections (or too many) are
allowed.
- If you do not want x11vnc to listen on ANY TCP interface
(evidently you are using -connect or -connect_or_exit, or
plan to use remote control: -R connect:host, or to use
-unixsock), specify -rfbport 0
- IPv6: if IPv6 is supported, this option automatically
implies the IPv6 loopback address '::1' as well.
-unixsock str
- In addition to the regular TCP port, listen on the unix
socket (AF_UNIX) 'str' for incoming connections. This mode is for either
local connections or a tunnel endpoint where one wants the file permission
of the unix socket file to determine what can connect to it. Example:
mkdir ~/s; chmod 700 ~/s; x11vnc -unixsock ~/s/mysock
-rfbport 0 ... same as: x11vnc -unixsockonly ~/s/mysock ...
(see -unixsockonly below.)
- This mode currently requires the modified libvncserver
bundled in the the x11vnc 0.9.13 tarball and later.
- Note that the SSVNC unix vncviewer can connect to unix
sockets, for example: ssvnc -viewer unix=./s/mysock
- As a special mechanism, if 'str' for either
-unixsock or -unixsockonly is of the form "fd=n"
where n is a non-negative decimal integer, then instead of creating a unix
socket, that file descriptor (assumed already opened and O_RDWR) will be
attached as a VNC client. Perhaps the program that execs x11vnc has
created a socketpair(2) to communicate over. Use this mechanism if
-inetd (which is basically fd=0) is not flexible enough for
you.
-unixsockonly str
- Listen on unix socket 'str' only, no TCP ports. First note
that one can disable all tcp listening ports by specifying '-rfbport 0'.
The option '-unixsockonly str' is functionally equivalent to '-unixsock
str -rfbport 0'
-listen6 str
- When in IPv6 listen mode "-6", listen only on the
network interface with address str. It also works for link scope
addresses (fe80::219:dbff:fee5:3f92%eth0) and IPv6 hostname strings (e.g.
ipv6.google.com.) Use LibVNCServer -listen option for the IPv4
interface.
-nolookup
- Do not use gethostbyname() or gethostbyaddr() to look up
host names or IP numbers. Use this if name resolution is incorrectly set
up and leads to long pauses as name lookups time out, etc.
-input string
- Fine tuning of allowed user input. If string does
not contain a comma "," the tuning applies only to normal
clients. Otherwise the part before "," is for normal clients and
the part after for view-only clients. "K" is for Keystroke
input, "M" for Mouse-motion input, "B" for
Button-click input, "C" is for Clipboard input, and
"F" is for File transfer (ultravnc only). Their presence in the
string enables that type of input. E.g. " -input
M" means normal users can only move the mouse and "
-input KMBCF,M" lets normal users do anything and
enables view-only users to move the mouse. This option is ignored when a
global -viewonly is in effect (all input is discarded in that
case).
-grabkbd
- When VNC viewers are connected, attempt to the grab the
keyboard so a (non-malicious) user sitting at the physical display is not
able to enter keystrokes. This method uses XGrabKeyboard(3X11) and
so it is not secure and does not rule out the person at the physical
display injecting keystrokes by flooding the server with them, grabbing
the keyboard himself, etc. Some degree of cooperation from the person at
the display is assumed. This is intended for remote help-desk or
educational usage modes.
- Note: on some recent (12/2010) X servers and/or desktops,
-grabkbd no longer works: it prevents the window manager from
resizing windows and similar things. Try -ungrabboth below (might
not work.)
-grabptr
- As -grabkbd, but for the mouse pointer using
XGrabPointer(3X11). Unfortunately due to the way the X server
works, the mouse can still be moved around by the user at the physical
display, but he will not be able to change window focus with it. Also some
window managers that call XGrabServer(3X11) for resizes, etc, will
act on the local user's input. Again, some degree of cooperation from the
person at the display is assumed.
-ungrabboth
- Whenever there is any input (either keyboard or pointer),
ungrab *both* the keyboard and the pointer while injecting the synthetic
input. This is to allow window managers, etc. a chance to grab.
-grabalways
- Apply both -grabkbd and -grabptr even when no
VNC viewers are connected. If you only want one of them, use the -R
remote control to turn the other back on, e.g. -R nograbptr.
- (PASSWORDS: Note that the LibVNCServer password options
" -rfbauth file" and "-passwd
str" are described at the bottom of the help output.)
-viewpasswd string
- Supply a 2nd password for view-only logins. The
-passwd (full-access) password must also be supplied.
-passwdfile filename
- Specify the LibVNCServer password via the first line of the
file filename (instead of via -passwd on the command line
where others might see it via ps(1) ).
- See the descriptions below for how to supply multiple
passwords, view-only passwords, to specify external programs for the
authentication, and other features.
- If the filename is prefixed with "rm:" it will be
removed after being read. Perhaps this is useful in limiting the
readability of the file. In general, the password file should not be
readable by untrusted users (BTW: neither should the VNC -rfbauth
file: it is NOT encrypted, only obscured with a fixed key).
- If the filename is prefixed with "read:" it will
periodically be checked for changes and reread. It is guaranteed to be
reread just when a new client connects so that the latest passwords will
be used.
- If filename is prefixed with "cmd:" then
the string after the ":" is run as an external command: the
output of the command will be interpreted as if it were read from a
password file (see below). If the command does not exit with 0, then
x11vnc terminates immediately. To specify more than 1000 passwords this
way set X11VNC_MAX_PASSWDS before starting x11vnc. The environment
variables are set as in -accept.
- Note that due to the VNC protocol only the first 8
characters of a password are used (DES key).
- If filename is prefixed with "custom:"
then a custom password checker is supplied as an external command
following the ":". The command will be run when a client
authenticates. If the command exits with 0 the client is accepted,
otherwise it is rejected. The environment variables are set as in
-accept.
- The standard input to the custom command will be a decimal
digit "len" followed by a newline. "len" specifies the
challenge size and is usually 16 (the VNC spec). Then follows len bytes
which is the random challenge string that was sent to the client. This is
then followed by len more bytes holding the client's response (i.e. the
challenge string encrypted via DES with the user password in the standard
situation).
- The "custom:" scheme can be useful to implement
dynamic passwords or to implement methods where longer passwords and/or
different encryption algorithms are used. The latter will require
customizing the VNC client as well. One could create an MD5SUM based
scheme for example. See also -unixpw_cmd below.
- File format for -passwdfile:
- If multiple non-blank lines exist in the file they are all
taken as valid passwords. Blank lines are ignored. Password lines may be
"commented out" (ignored) if they begin with the character
"#" or the line contains the string "__SKIP__". Lines
may be annotated by use of the "__COMM__" string: from it to the
end of the line is ignored. An empty password may be specified via the
"__EMPTY__" string on a line by itself (note your viewer might
not accept empty passwords).
- If the string "__BEGIN_VIEWONLY__" appears on a
line by itself, the remaining passwords are used for viewonly access. For
compatibility, as a special case if the file contains only two password
lines the 2nd one is automatically taken as the viewonly password.
Otherwise the "__BEGIN_VIEWONLY__" token must be used to have
viewonly passwords. (tip: make the 3rd and last line be
"__BEGIN_VIEWONLY__" to have 2 full-access passwords)
-showrfbauth filename
- Print to the screen the obscured VNC password kept in the
rfbauth file filename and then exit.
-usepw
- If no other password method was supplied on the command
line, first look for ~/.vnc/passwd and if found use it with
-rfbauth; next, look for ~/.vnc/passwdfile and use it with
-passwdfile; otherwise, prompt the user for a password to create
~/.vnc/passwd and use it with the -rfbauth option. If none of these
succeed x11vnc exits immediately.
-storepasswd pass file
- Store password pass as the VNC password in the file
file. Once the password is stored the program exits. Use the
password via " -rfbauth file"
- If called with no arguments, "x11vnc
-storepasswd", the user is prompted for a password and it is
stored in the file ~/.vnc/passwd. Called with one argument, that will be
the file to store the prompted password in.
-nopw
- Disable the big warning message when you use x11vnc without
some sort of password.
-accept string
- Run a command (possibly to prompt the user at the X11
display) to decide whether an incoming client should be allowed to connect
or not. string is an external command run via system(3) or
some special cases described below. Be sure to quote string if it
contains spaces, shell characters, etc. If the external command returns 0
the client is accepted, otherwise the client is rejected. See below for an
extension to accept a client view-only.
- If x11vnc is running as root (say from inetd(8) or
from display managers xdm(1) , gdm(1) , etc), think about
the security implications carefully before supplying this option (likewise
for the -gone option).
- Environment: The RFB_CLIENT_IP environment variable will be
set to the incoming client IP number and the port in RFB_CLIENT_PORT (or
-1 if unavailable). Similarly, RFB_SERVER_IP and RFB_SERVER_PORT (the
x11vnc side of the connection), are set to allow identification of the tcp
virtual circuit. The x11vnc process id will be in RFB_X11VNC_PID, a client
id number in RFB_CLIENT_ID, and the number of other connected clients in
RFB_CLIENT_COUNT. RFB_MODE will be "accept". RFB_STATE will be
PROTOCOL_VERSION, SECURITY_TYPE, AUTHENTICATION, INITIALISATION, NORMAL,
or UNKNOWN indicating up to which state the client has achieved.
RFB_LOGIN_VIEWONLY will be 0, 1, or -1 (unknown). RFB_USERNAME,
RFB_LOGIN_TIME, and RFB_CURRENT_TIME may also be set.
- If string is "popup" then a builtin popup
window is used. The popup will time out after 120 seconds, use
"popup:N" to modify the timeout to N seconds (use 0 for no
timeout).
- In the case of "popup" and when the
-unixpw option is specified, then a *second* window will be popped
up after the user successfully logs in via his UNIX password. This time
the user will be identified as UNIX:username@hostname, the
"UNIX:" prefix indicates which user the viewer logged as via
-unixpw. The first popup is only for whether to allow him to even
*try* to login via unix password.
- If string is "xmessage" then an
xmessage(1) invocation is used for the command. xmessage must be
installed on the machine for this to work.
- Both "popup" and "xmessage" will
present an option for accepting the client "View-Only" (the
client can only watch). This option will not be presented if
-viewonly has been specified, in which case the entire display is
view only.
- If the user supplied command is prefixed with something
like "yes:0,no:*,view:3 mycommand ..." then this associates the
numerical command return code with the actions: accept, reject, and
accept-view-only, respectively. Use "*" instead of a number to
indicate the default action (in case the command returns an unexpected
value). E.g. "no:*" is a good choice.
- Note that x11vnc blocks while the external command or popup
is running (other clients may see no updates during this period). So a
person sitting a the physical display is needed to respond to an popup
prompt. (use a 2nd x11vnc if you lock yourself out).
- More -accept tricks: use "popupmouse" to
only allow mouse clicks in the builtin popup to be recognized. Similarly
use "popupkey" to only recognize keystroke responses. These are
to help avoid the user accidentally accepting a client by typing or
clicking. All 3 of the popup keywords can be followed by +N+M to supply a
position for the popup window. The default is to center the popup
window.
-afteraccept string
- As -accept, except to run a user supplied command
after a client has been accepted and authenticated. RFB_MODE will be set
to "afteraccept" and the other RFB_* variables are as in
-accept. Unlike -accept, the command return code is not
interpreted by x11vnc. Example: -afteraccept 'killall xlock
&'
-gone string
- As -accept, except to run a user supplied command
when a client goes away (disconnects). RFB_MODE will be set to
"gone" and the other RFB_* variables are as in -accept.
The "popup" actions apply as well. Unlike -accept, the
command return code is not interpreted by x11vnc. Example: -gone
'xlock &'
-unixpw [list]
- Use Unix username and password authentication. x11vnc will
use the su(1) program to verify the user's password. [list] is an
optional comma separated list of allowed Unix usernames. If the [list]
string begins with the character "!" then the entire list is
taken as an exclude list. See below for per-user options that can be
applied.
- A familiar "login:" and "Password:"
dialog is presented to the user on a black screen inside the vncviewer.
The connection is dropped if the user fails to supply the correct password
in 3 tries or does not send one before a 45 second timeout. Existing
clients are view-only during this period.
- If the first character received is "Escape" then
the unix username will not be displayed after "login:" as it is
typed. This could be of use for VNC viewers that automatically type the
username and password.
- Since the detailed behavior of su(1) can vary from
OS to OS and for local configurations, test the mode before deployment to
make sure it is working properly. x11vnc will attempt to be conservative
and reject a login if anything abnormal occurs.
- One case to note: FreeBSD and the other BSD's by default it
is impossible for the user running x11vnc to validate his *own* password
via su(1) (commenting out the pam_self.so entry in /etc/pam.d/su
eliminates this behavior). So the x11vnc login will always *FAIL* for this
case (even when the correct password is supplied).
- A possible workaround for this on *BSD would be to start
x11vnc as root with the " -users +nobody" option
to immediately switch to user nobody where the su'ing will proceed
normally.
- Another source of potential problems are PAM modules that
prompt for extra info, e.g. password aging modules. These logins will fail
as well even when the correct password is supplied.
- **IMPORTANT**: to prevent the Unix password being sent in
*clear text* over the network, one of two schemes will be enforced: 1) the
-ssl builtin SSL mode, or 2) require both -localhost and
-stunnel be enabled.
- Method 1) ensures the traffic is encrypted between viewer
and server. A PEM file will be required, see the discussion under
-ssl below (under some circumstances a temporary one can be
automatically generated).
- Method 2) requires the viewer connection to appear to come
from the same machine x11vnc is running on (e.g. from a ssh -L port
redirection). And that the -stunnel SSL mode be used for encryption
over the network. (see the description of -stunnel below).
- Note: as a convenience, if you ssh(1) in and start
x11vnc it will check if the environment variable SSH_CONNECTION is set and
appears reasonable. If it does, then the -ssl or -stunnel
requirement will be dropped since it is assumed you are using ssh for the
encrypted tunnelling. -localhost is still enforced. Use -ssl
or -stunnel to force SSL usage even if SSH_CONNECTION is set.
- To override the above restrictions you can set environment
variables before starting x11vnc:
- Set UNIXPW_DISABLE_SSL=1 to disable requiring either
-ssl or -stunnel (as under SSH_CONNECTION.) Evidently you
will be using a different method to encrypt the data between the vncviewer
and x11vnc: perhaps ssh(1) or an IPSEC VPN. -localhost is
still enforced (however, see the next paragraph.)
- Set UNIXPW_DISABLE_LOCALHOST=1 to disable the
-localhost requirement in -unixpw modes. One should never do
this (i.e. allow the Unix passwords to be sniffed on the network.) This
also disables the localhost requirement for reverse connections (see
below.)
- Note that use of -localhost with ssh(1) (and
no -unixpw) is roughly the same as requiring a Unix user login
(since a Unix password or the user's public key authentication is used by
sshd on the machine where x11vnc runs and only local connections from that
machine are accepted).
- Regarding reverse connections (e.g. -R connect:host
and -connect host), when the -localhost constraint is in
effect then reverse connections can only be used to connect to the same
machine x11vnc is running on (default port 5500). Please use a ssh or
stunnel port redirection to the viewer machine to tunnel the reverse
connection over an encrypted channel.
- In -inetd mode the Method 1) will be enforced (not
Method 2). With -ssl in effect reverse connections are disabled. If
you override this via env. var, be sure to also use encryption from the
viewer to inetd. Tip: you can also have your own stunnel spawn x11vnc in
-inetd mode (thereby bypassing inetd). See the FAQ for
details.
- The user names in the comma separated [list] may have
per-user options after a ":", e.g. "fred:opts" where
"opts" is a "+" separated list of
"viewonly", "fullaccess", "input=XXXX", or
"deny", e.g. "karl,wally:viewonly,boss:input=M". For
"input=" it is the K,M,B,C described under -input.
- If an item in the list is "*" that means those
options apply to all users. It ALSO implies all users are allowed to log
in after supplying a valid password. Use "deny" to explicitly
deny some users if you use "*" to set a global option. If [list]
begins with the "!" character then "*" is ignored for
checking if the user is allowed, but the option values associated with it
do apply as normal.
- There are also some utilities for checking passwords if
[list] starts with the "%" character. See the quick_pw()
function for more details. Description: "%-" or
"%stdin" means read one line from stdin. "%stdin2"
means read the username from the first stdin line and the password from
the seconde stdin line. "%env" means it is in $UNIXPW env var. A
leading "%/" or "%." means read the first line from
the filename that follows after the % character. % by itself means prompt
for the username and password. Otherwise: %user:pass E.g. -unixpw
%fred:swordfish For the other cases user:pass is read from the indicated
source. If the password is correct ´Y user' is printed and the
program exit code is 0. If the password is incorrect it prints 'N user'
and the exit code is 1. If there is some other error the exit code is 2.
This feature enables x11vnc to be a general unix user password checking
tool; it could be used from scripts or other programs. These % password
checks also apply to the -unixpw_nis and -unixpw_cmd
options.
- For the % password check, if the env. var. UNIXPW_CMD is
set to a command then it is run as the user (assuming the password is
correct.) The output of the command is not printed, the program or script
must manage that by some other means. The exit code of x11vnc will depend
on the exit code of the command that is run.
- Use -nounixpw to disable unixpw mode if it was
enabled earlier in the cmd line (e.g. -svc mode)
-unixpw_nis [list]
- As -unixpw above, however do not use su(1)
but rather use the traditional getpwnam(3) + crypt(3) method
to verify passwords. All of the above -unixpw options and
constraints apply.
- This mode requires that the encrypted passwords be
readable. Encrypted passwords stored in /etc/shadow will be inaccessible
unless x11vnc is run as root.
- This is called "NIS" mode simply because in most
NIS setups user encrypted passwords are accessible (e.g. "ypcat
passwd") by an ordinary user and so that user can authenticate ANY
user.
- NIS is not required for this mode to work (only that
getpwnam(3) return the encrypted password is required), but it is
unlikely it will work (as an ordinary user) for most modern environments
unless NIS is available. On the other hand, when x11vnc is run as root it
will be able to to access /etc/shadow even if NIS is not available (note
running as root is often done when running x11vnc from inetd and
xdm/gdm/kdm).
- Looked at another way, if you do not want to use the
su(1) method provided by -unixpw (i.e. su_verify()), you can
run x11vnc as root and use -unixpw_nis. Any users with passwords in
/etc/shadow can then be authenticated.
- In -unixpw_nis mode, under no circumstances is
x11vnc's user password verifying function based on su called (i.e. the
function su_verify() that runs /bin/su in a pseudoterminal to verify
passwords.) However, if -unixpw_nis is used in conjunction with the
-find and -create -display WAIT:... modes then, if
x11vnc is running as root, /bin/su may be called externally to run the
find or create commands.
-unixpw_cmd cmd
- As -unixpw above, however do not use su(1)
but rather run the externally supplied command cmd. The first line
of its stdin will be the username and the second line the received
password. If the command exits with status 0 (success) the VNC user will
be accepted. It will be rejected for any other return status.
- Dynamic passwords and non-unix passwords, e.g. LDAP, can be
implemented this way by providing your own custom helper program. Note
that the remote viewer is given 3 tries to enter the correct password, and
so the program may be called in a row that many (or more) times.
- If a list of allowed users is needed to limit who can log
in, use -unixpw [list] in addition to this option.
- In FINDDISPLAY and FINDCREATEDISPLAY modes the cmd
will also be run with the RFB_UNIXPW_CMD_RUN env. var. non-empty and set
to the corresponding display find/create command. The first two lines of
input are the username and passwd as in the normal case described above.
To support FINDDISPLAY and FINDCREATEDISPLAY, cmd should run the
requested command as the user (and most likely refusing to run it if the
password is not correct.) Here is an example script (note it has a
hardwired bogus password "abc"!)
- #!/bin/sh # Example x11vnc -unixpw_cmd script. #
Read the first two lines of stdin (user and passwd) read user read
pass
- debug=0 if [ $debug = 1 ]; then echo "user:
$user" 1>&2 echo "pass: $pass" 1>&2 env |
egrep -i 'rfb|vnc' 1>&2 fi
- # Check if the password is valid. # (A real example would
use ldap lookup, etc!) if [ "X$pass" != "Xabc" ]; then
exit 1 # incorrect password fi
- if [ "X$RFB_UNIXPW_CMD_RUN" = "X" ];
then exit 0 # correct password else # Run the requested command
(finddisplay) if [ $debug = 1 ]; then echo "run:
$RFB_UNIXPW_CMD_RUN" 1>&2 fi exec /bin/su - "$user"
-c "$RFB_UNIXPW_CMD_RUN" fi exit 1
- In -unixpw_cmd mode, under no circumstances is
x11vnc's user password verifying function based on su called (i.e. the
function su_verify() that runs /bin/su in a pseudoterminal to verify
passwords.) It is up to the supplied unixpw_cmd to do user switching if
desired and if it has the permissions to do so.
- See also "-passwdfile custom:..."
above for a non unix username based custom password checking
interface.
-find
- Find the user's display using FINDDISPLAY. This is an alias
for " -display WAIT:cmd=FINDDISPLAY".
- Note: if a -display occurs later on the command line
it will override the -find setting.
- For this and the next few options see -display
WAIT:... below for all of the details.
-finddpy
- Run the FINDDISPLAY program, print out the found display
(if any) and exit. Output is like: DISPLAY=:0.0 DISPLAY=:0.0,XPID=12345 or
DISPLAY=:0.0,VT=7. XPID is the process ID of the found X server. VT is the
Linux virtual terminal of the X server.
-listdpy
- Have the FINDDISPLAY program list all of your displays
(i.e. all the X displays on the local machine that you have access rights
to). x11vnc then exits.
-findauth [disp]
- Apply the -find/-finddpy heuristics to try to guess
the XAUTHORITY file for DISPLAY 'disp'. If 'disp' is not supplied, then
the value in the -display on the cmdline is used; failing that
$DISPLAY is used; and failing that ":0" is used. x11vnc then
exits.
- If nothing is printed out, that means no XAUTHORITY was
found for 'disp'; i.e. failure. If "XAUTHORITY=" is printed out,
that means use the default (i.e. do not set XAUTHORITY). If
"XAUTHORITY=/path/to/file" is printed out, then use that
file.
- XDM/GDM/KDM: if you are running x11vnc as root and want to
find the XAUTHORITY before anyone has logged into an X session yet, use:
x11vnc -env FD_XDM=1 -findauth ... (This will also find the
XAUTHORITY if a user is already logged into the X session.) When running
as root, FD_XDM=1 will be tried if the initial -findauth
fails.
-create
- First try to find the user's display using FINDDISPLAY, if
that doesn't succeed create an X session via the FINDCREATEDISPLAY method.
This is an alias for " -display
WAIT:cmd=FINDCREATEDISPLAY-Xvfb".
- Note: if a -display occurs later on the command line
it will override the -create setting.
- SSH NOTE: for both -find and -create you can
(should!) add the " -localhost" option to force SSH
tunnel access.
-xdummy
- As in -create, except Xdummy instead of Xvfb.
-xvnc
- As in -create, except Xvnc instead of Xvfb.
-xvnc_redirect
- As in -create, except Xvnc.redirect instead of
Xvfb.
-xdummy_xvfb
- Sets WAIT:cmd=FINDCREATEDISPLAY-Xdummy,Xvfb
-create_xsrv str
- Sets WAIT:cmd=FINDCREATEDISPLAY-<str> Can be on
cmdline after anything that sets WAIT:.. and other things (e.g.
-svc, -xdmsvc) to adjust the X server list. Example:
-svc ... -create_xsrv Xdummy,X
-svc
- Terminal services mode based on SSL access. Alias for
-display WAIT:cmd=FINDCREATEDISPLAY-Xvfb -unixpw
-users unixpw= -ssl SAVE Also
"-service".
- Note: if a -display, -unixpw, -users,
or -ssl occurs later on the command line it will override the
-svc setting.
-svc_xdummy
- As -svc except Xdummy instead of Xvfb.
-svc_xvnc
- As -svc except Xvnc instead of Xvfb.
-svc_xdummy_xvfb
- As -svc with Xdummy,Xvfb.
-xdmsvc
- Display manager Terminal services mode based on SSL. Alias
for -display WAIT:cmd=FINDCREATEDISPLAY-Xvfb.xdmcp -unixpw
-users unixpw= -ssl SAVE Also
"-xdm_service".
- Note: if a -display, -unixpw, -users,
or -ssl occurs later on the command line it will override the
-xdmsvc setting.
- To create a session a user will have to first log in to the
-unixpw dialog and then log in again to the XDM/GDM/KDM prompt.
Subsequent re-connections will only require the -unixpw password.
See the discussion under -display WAIT:... for more details about
XDM, etc configuration.
- Remember to enable XDMCP in the xdm-config, gdm.conf, or
kdmrc configuration file. See -display WAIT: for more info.
-sshxdmsvc
- Display manager Terminal services mode based on SSH. Alias
for -display WAIT:cmd=FINDCREATEDISPLAY-Xvfb.xdmcp
-localhost.
- The -localhost option constrains connections to come
in via a SSH tunnel (which will require a login). To create a session a
user will also have to log into the XDM GDM KDM prompt. Subsequent
re-connections will only only require the SSH login. See the discussion
under -display WAIT:... for more details about XDM, etc
configuration.
- Remember to enable XDMCP in the xdm-config, gdm.conf, or
kdmrc configuration file. See -display WAIT: for more info.
-unixpw_system_greeter
- Present a "Press 'Escape' for System Greeter"
option to the connecting VNC client in combined -unixpw and xdmcp
FINDCREATEDISPLAY modes (e.g. -xdmsvc).
- Normally in a -unixpw mode the VNC client must
supply a valid username and password to gain access. However, if
-unixpw_system_greeter is supplied AND the FINDCREATEDISPLAY
command matches 'xdmcp', then the user has the option to press Escape and
then get a XDM/GDM/KDM login/greeter panel instead. They will then supply
a username and password directly to the greeter.
- Otherwise, in xdmcp FINDCREATEDISPLAY mode the user must
supply his username and password TWICE. First to the initial unixpw login
dialog, and second to the subsequent XDM/GDM/KDM greeter. Note that if the
user re-connects and supplies his username and password in the unixpw
dialog the xdmcp greeter is skipped and he is connected directly to his
existing X session. So the -unixpw_system_greeter option avoids the
extra password at X session creation time.
- Example: x11vnc -xdmsvc
-unixpw_system_greeter See -unixpw and -display
WAIT:... for more info.
- The special options after a colon at the end of the
username (e.g. user:solid) described under -display WAIT: are also
applied in this mode if they are typed in before the user hits Escape. The
username is ignored but the colon options are not.
- The default message is 2 lines in a small font, set the
env. var. X11VNC_SYSTEM_GREETER1=true for a 1 line message in a larger
font.
- If the user pressed Escape the FINDCREATEDISPLAY command
will be run with the env. var. X11VNC_XDM_ONLY=1.
- Remember to enable XDMCP in the xdm-config, gdm.conf, or
kdmrc configuration file. See -display WAIT: for more info.
-redirect port
- As in FINDCREATEDISPLAY-Xvnc.redirect mode except redirect
immediately (i.e. without X session finding or creation) to a VNC server
listening on port. You can also supply host:port to redirect to a
different machine.
- If 0 <= port < 200 it is taken as a VNC display (5900
is added to get the actual port), if port < 0 then -port is
used.
- Probably the only reason to use the -redirect option
is in conjunction with SSL support, e.g. -ssl SAVE. This provides
an easy way to add SSL encryption to a VNC server that does not support
SSL (e.g. Xvnc or vnc.so) In fact, the protocol does not even need to be
VNC, and so " -rfbport port1 -ssl SAVE
-redirect host:port2" can act as a replacement for
stunnel(1).
- This mode only allows one redirected connection. The
-forever option does not apply. Use -inetd or -loop
for persistent service.
-display WAIT:...
- A special usage mode for the normal -display option.
Useful with -unixpw, but can be used independently of it. If the
display string begins with WAIT: then x11vnc waits until a VNC client
connects before opening the X display (or -rawfb device).
- This could be useful for delaying opening the display for
certain usage modes (say if x11vnc is started at boot time and no X server
is running or users logged in yet).
- If the string is, e.g. WAIT:0.0 or WAIT:1, i.e.
"WAIT" in front of a normal X display, then that indicated
display is used.
- One can also insert a geometry between colons, e.g.
WAIT:1280x1024:... to set the size of the display the VNC client first
attaches to since some VNC viewers will not automatically adjust to a new
framebuffer size.
- A more interesting case is like this:
- WAIT:cmd=/usr/local/bin/find_display
- in which case the command after "cmd=" is run to
dynamically work out the DISPLAY and optionally the XAUTHORITY data. The
first line of the command output must be of the form
DISPLAY=<xdisplay>. On Linux if the virtual terminal is known append
",VT=n" to this string and the chvt(1) program will also
be run. Any remaining output is taken as XAUTHORITY data. It can be either
of the form XAUTHORITY=<file> or raw xauthority data for the
display. For example;
- xauth extract - $DISPLAY"
- NOTE: As specified in the previous paragraph, you can
supply your own WAIT:cmd=... program or script, BUT there are two very
useful *BUILT-IN* ones: FINDDISPLAY (alias -find above) and
FINDCREATEDISPLAY (alias -create above.) Most people use these
instead of creating their own script. Read the following (especially the
BUILT-IN modes sections) to see how to configure these two useful builtin
-display WAIT: modes.
- In the case of -unixpw (and -unixpw_nis only
if x11vnc is running as root), then the cmd= command is run as the user
who just authenticated via the login and password prompt.
- In the case of -unixpw_cmd, the commands will also
be run as the logged-in user, as long as the user-supplied helper program
supports RFB_UNIXPW_CMD_RUN (see the -unixpw_cmd option.)
- Also in the case of -unixpw, the user logging in can
place a colon at the end of her username and supply a few options: scale=,
scale_cursor= (or sc=), solid (or so), id=, clear_mods (or cm), clear_keys
(or ck), clear_all (or ca), repeat, speeds= (or sp=), readtimeout= (or
rd=), viewonly (or vo), nodisplay= (or nd=), rotate= (or ro=), or noncache
(or nc), all separated by commas if there is more than one. After the user
logs in successfully, these options will be applied to the VNC screen. For
example,
- login: fred:scale=3/4,sc=1,repeat Password: ...
- login: runge:sp=modem,rd=120,solid
- for convenience m/n implies scale= e.g. fred:3/4 If you
type and enter your password incorrectly, to retrieve your long
"login:" line press the Up arrow once (before typing anything
else).
- Most of these colon options only apply to the builtin
FINDDISPLAY and FINDCREATEDISPLAY modes, but note that they are passed to
the extrenal command in the environment as well and so could be used.
- In the login panel, press F1 to get a list of the available
options that you can add after the username.
- Another option is "geom=WxH" or
"geom=WxHxD" (or ge=). This only has an effect in
FINDCREATEDISPLAY mode when a virtual X server such as Xvfb is going to be
created. It sets the width and height of the new display, and optionally
the color depth as well.
- You can also supply "gnome", "kde",
"twm", "fvwm", "mwm", "dtwm",
"wmaker", "xfce", "lxde",
"enlightenment", "Xsession", or "failsafe"
(same as "xterm") to have the created display use that mode for
the user session.
- Specify "tag=..." to set the unique FD_TAG
desktop session tag described below. Note: this option will be ignored if
the FD_TAG env. var. is already set or if the viewer-side supplied value
is not completely composed of alphanumeric or '_' or '-' characters.
- User preferences file: Instead of having the user type in
geom=WxH,... etc. every time he logs in to find or create his X session,
if you set FD_USERPREFS to a string that does not contain the
"/" character, then the user's home directory is prepended to
that string and if the file exists its first line is read and appended to
any options he supplied at the login: prompt. For example -env
FD_USERPREFS=.x11vnc_create and the user put "geom=1600x1200" in
his ~/.x11vnc_create file.
- To disable the option setting set the environment variable
X11VNC_NO_UNIXPW_OPTS=1 before starting x11vnc. To set any other options,
the user can use the gui (x11vnc -gui connect) or the remote
control method (x11vnc -R opt:val) during his VNC session.
- So we see the combination of -display WAIT:cmd=...
and -unixpw allows automatic pairing of an unix authenticated VNC
user with his desktop. This could be very useful on SunRays and also any
system where multiple users share a given machine. The user does not need
to remember special ports or passwords set up for his desktop and
VNC.
- A nice way to use WAIT:cmd=... is out of inetd(8)
(it automatically forks a new x11vnc for each user). You can have the
x11vnc inetd spawned process run as, say, root or nobody. When run as root
(for either inetd or display manager), you can also supply the option
" -users unixpw=" to have the x11vnc process
switch to the user as well. Note: there will be a 2nd SSL helper process
that will not switch, but it is only encoding and decoding the encrypted
stream at that point.
- BUILT-IN modes:
- -- Automatic Finding of User X Sessions
--
- As a special case, WAIT:cmd=FINDDISPLAY will run a script
that works on most Unixes to determine a user's DISPLAY variable and
xauthority data (see who(1) ).
- NOTE: The option "-find" is an alias for
this mode.
- To have this default script printed to stdout (e.g. for
customization) run with WAIT:cmd=FINDDISPLAY-print To have the script run
to print what display it would find use " -finddpy" or
WAIT:cmd=FINDDISPLAY-run
- The standard script runs xdpyinfo(1) run on
potential displays. If your X server(s) have a login greeter that
exclusively grabs the Xserver, then xdpyinfo blocks forever and this mode
will not work. See www.karlrunge.com/x11vnc/faq.html#faq-display-manager
for how to disable this for dtgreet on Solaris and possibly for other
greeters.
- In -find/cmd=FINDDISPLAY mode, if you set FD_XDM=1,
e.g. 'x11vnc -env FD_XDM=1 -find ...' and x11vnc is running
as root (e.g. inetd) then it will try to find the XAUTHORITY file of a
running XDM/GDM/KDM login greeter (i.e. no user has logged into an X
session yet.)
- As another special case, WAIT:cmd=HTTPONCE will allow
x11vnc to service one http request and then exit. This is usually done in
-inetd mode to run on, say, port 5800 and allow the Java vncviewer
to be downloaded by client web browsers. For example:
- 5815 stream tcp nowait root /usr/sbin/tcpd /.../x11vnc \
-inetd -q -http_ssl -prog /.../x11vnc \
-display WAIT:cmd=HTTPONCE
- Where /.../x11vnc is the full path to x11vnc. It is used in
the Apache SSL-portal example (see FAQ).
- In this mode you can set X11VNC_SKIP_DISPLAY to a comma
separated list of displays (e.g. ":0,:1") to ignore in the
finding process. The ":" is optional. Ranges n-m e.g. 0-20 can
also be supplied. This string can also be set by the connecting user via
"nd=" using "+" instead of "," If
"nd=all" or you set X11VNC_SKIP_DISPLAY=all then all display
finding fails as if you set X11VNC_FINDDISPLAY_ALWAYS_FAILS=1
(below.)
- On some systems lsof(1) can be very slow. Set the
env. var. FIND_DISPLAY_NO_LSOF=1 to skip using lsof to try to find the
Linux VT the X server is running on. set FIND_DISPLAY_NO_VT_FIND=1 to
avoid looking at all.
- -- Automatic Creation of User X Sessions
--
- An interesting option is WAIT:cmd=FINDCREATEDISPLAY that is
like FINDDISPLAY in that is uses the same method to find an existing
display. However, if it does not find one it will try to *start* up an X
server session for the user. This is the only time x11vnc tries to
actually start up an X server.
- NOTE: The option "-create" is an alias for
this mode.
- It will start looking for an open display number at :20
Override via X11VNC_CREATE_STARTING_DISPLAY_NUMBER=n By default 80 X
displays are allowed (i.e. going to :99) Override via
X11VNC_CREATE_MAX_DISPLAYS=n
- For its heuristics, the create display script sets LC_ALL=C
so that command output is uniform. By default it will try to restore
LC_ALL right before starting the user session. However, if you don't mind
it keeping LC_ALL=C set the env. var.: X11VNC_CREATE_LC_ALL_C_OK=1
- By default FINDCREATEDISPLAY will try Xvfb and then
Xdummy:
- The Xdummy wrapper is part of the x11vnc source code
(x11vnc/misc/Xdummy) It should be available in PATH and have run
"Xdummy -install" once to create the shared library.
Xdummy only works on Linux. As of 12/2009 it no longer needs to be run as
root, and the default is to not run as root. In some circumstances
permissions may require running it as root, in these cases specify
FD_XDUMMY_RUN_AS_ROOT=1, this is the same as supplying -root to the
Xdummy cmdline.
- Xvfb is available on most platforms and does not require
root.
- An advantage of Xdummy over Xvfb is that Xdummy supports
RANDR dynamic screen resizing.
- When x11vnc exits (i.e. user disconnects) the X server
session stays running in the background. The FINDDISPLAY will find it
directly next time. The user must exit the X session in the usual way for
it to terminate (or kill the X server process if all else fails).
- To troubleshoot the FINDCREATEDISPLAY mechanism, set the
following env. var. to an output log file, e.g -env
CREATE_DISPLAY_OUTPUT=/tmp/mydebug.txt
- So this is a somewhat odd mode for x11vnc in that it will
start up and poll virtual X servers! This can be used from, say,
inetd(8) to provide a means of definitely getting a desktop (either
real or virtual) on the machine. E.g. a desktop service:
- 5900 stream tcp nowait root /usr/sbin/tcpd /.../x11vnc
-inetd -q -http -ssl SAVE -unixpw
-users unixpw=\ -passwd secret -prog /.../x11vnc \
-display WAIT:cmd=FINDCREATEDISPLAY
- Where /.../x11vnc is the full path to x11vnc.
- See the -svc/-service option alias above.
- If for some reason you do not want x11vnc to ever try to
find an existing display set the env. var
X11VNC_FINDDISPLAY_ALWAYS_FAILS=1 (also -env ...) This is the same
as setting X11VNC_SKIP_DISPLAY=all or supplying "nd=all" after
"username:"
- Use WAIT:cmd=FINDCREATEDISPLAY-print to print out the
script that is used for this.
- You can specify the preferred X server order via e.g.,
WAIT:cmd=FINDCREATEDISPLAY-Xdummy,Xvfb,X and/or leave out ones you do not
want. The the case "X" means try to start up a real, hardware X
server using xinit(1) or startx(1). If there is already an X
server running the X case may only work on Linux (see startx(1)
).
- "Xvnc" will start up a VNC X server (real- or
tight-vnc, e.g. use if Xvfb is not available). "Xsrv" will start
up the server program in the variable "FD_XSRV" if it is
non-empty. You can make this be a wrapper script if you like (it must
handle :N, -geometry, and -depth and other X server
options).
- You can set the environment variable FD_GEOM (or
X11VNC_CREATE_GEOM) to WxH or WxHxD to set the width and height and
optionally the color depth of the created display. You can also set
FD_SESS to be the session (short name of the windowmanager: kde, gnome,
twm, failsafe, etc.). FD_OPTS contains extra options to pass to the X
server. You can also set FD_PROG to be the full path to the
session/windowmanager program.
- More FD tricks: FD_CUPS=port or FD_CUPS=host:port will set
the cups printing environment. Similarly for FD_ESD=port or
FD_ESD=host:port for esddsp sound redirection. Set FD_EXTRA to a command
to be run a few seconds after the X server starts up. Set FD_TAG to be a
unique name for the session, it is set as an X property, that makes
FINDDISPLAY only find sessions with that tag value.
- Set FD_XDMCP_IF to the network interface that the display
manager is running on; default is 'localhost' but you may need to set it
to '::1' on some IPv6 only systems or misconfigured display managers.
- If you want the FINDCREATEDISPLAY session to contact an
XDMCP login manager (xdm/gdm/kdm) on the same machine, then use
"Xvfb.xdmcp" instead of "Xvfb", etc. The user will
have to supply his username and password one more time (but he gets to
select his desktop type so that can be useful). For this to work, you will
need to enable localhost XDMCP (udp port 177) for the display manager.
This seems to be:
- for gdm in gdm.conf: Enable=true in section [xdmcp] for kdm
in kdmrc: Enable=true in section [Xdmcp] for xdm in xdm-config:
DisplayManager.requestPort: 177
- See the shorthand options above "-svc",
" -xdmsvc" and " -sshxdmsvc" that
specify the above options for some useful cases.
- If you set the env. var WAITBG=1 x11vnc will go into the
background once listening in wait mode.
- Another special mode is FINDCREATEDISPLAY-Xvnc.redirect,
(or FINDDISPLAY-Xvnc.redirect). In this case it will start up Xvnc as
above if needed, but instead of polling it in its normal way, it simply
does a socket redirection of the connected VNC viewer to the Xvnc.
- So in Xvnc.redirect x11vnc does no VNC but merely transfers
the data back and forth. This should be faster then x11vnc's polling
method, but not as fast as connecting directly to the Xvnc with the VNC
Viewer. The idea here is to take advantage of x11vnc's display
finding/creating scheme, SSL, and perhaps a few others. Most of x11vnc's
options do not apply in this mode.
- Xvnc.redirect should also work for the vnc.so X server
module for the h/w display however it will work only for finding the
display and the user must already be logged into the X console.
-vencrypt mode
- The VeNCrypt extension to the VNC protocol allows encrypted
SSL/TLS connections. If the -ssl mode is enabled, then VeNCrypt is
enabled as well BY DEFAULT (they both use a SSL/TLS tunnel, only the
protocol handshake is a little different.)
- To control when and how VeNCrypt is used, specify the mode
string. If mode is "never", then VeNCrypt is not used. If mode
is "support" (the default) then VeNCrypt is supported. If mode
is "only", then the similar and older ANONTLS protocol is not
simultaneously supported. x11vnc's normal SSL mode (vncs://) will be
supported under -ssl unless you set mode to "force".
- If mode is prefixed with "nodh:", then Diffie
Hellman anonymous key exchange is disabled. If mode is prefixed with
"nox509:", then X509 key exchange is disabled.
- To disable all Anonymous Diffie-Hellman access (susceptible
to Man-In-The-Middle attack) you will need to supply "
-vencrypt nodh:support -anontls never" or "
-vencrypt nodh:only"
- If mode is prefixed with "newdh:", then new
Diffie Hellman parameters are generated for each connection (this can be
time consuming: 1-60 secs; see -dhparams below for a faster way)
rather than using the fixed values in the program. Using fixed, publicly
known values is not known to be a security problem. This setting applies
to ANONTLS as well.
- Long example: -vencrypt newdh:nox509:support
- Also, if mode is prefixed with "plain:", then if
-unixpw mode is active the VeNCrypt "*Plain"
username+passwd method is enabled for Unix logins. Otherwise in
-unixpw mode the normal login panel is provided.
- You *MUST* supply the -ssl option for VeNCrypt to be
active. The -vencrypt option only fine-tunes its operation.
-anontls mode
- The ANONTLS extension to the VNC protocol allows encrypted
SSL/TLS connections. If the -ssl mode is enabled, then ANONTLS is
enabled as well BY DEFAULT (they both use a SSL/TLS tunnel, only the
protocol handshake is a little different.)
- ANONTLS is an older SSL/TLS mode introduced by vino.
- It is referred to as 'TLS' for its registered VNC
security-type name, but we use the more descriptive ´ANONTLS' here
because it provides only Anonymous Diffie-Hellman encrypted connections,
and hence no possibility for certificate authentication.
- To control when and how ANONTLS is used, specify the mode
string. If mode is "never", then ANONTLS is not used. If mode is
"support" (the default) then ANONTLS is supported. If mode is
"only", then the similar VeNCrypt protocol is not simultaneously
supported. x11vnc's normal SSL mode (vncs://) will be supported under
-ssl unless you set mode to "force".
- If mode is prefixed with "newdh:", then new
Diffie Hellman parameters are generated for each connection (this can be
time consuming: 1-60 secs; see -dhparams below for a faster way)
rather than using the fixed values in the program. Using fixed, publicly
known values is not known to be a security problem. This setting applies
to VeNCrypt as well. See the description of "plain:" under
-vencrypt.
- Long example: -anontls newdh:plain:support
- You *MUST* supply the -ssl option for ANONTLS to be
active. The -anontls option only fine-tunes its operation.
-sslonly
- Same as: "-vencrypt never
-anontls never" i.e. it disables the VeNCrypt and ANONTLS
encryption methods and only allows standard SSL tunneling. You must also
supply the -ssl ... option (see below.)
-dhparams file
- For some operations a set of Diffie Hellman parameters
(prime and generator) is needed. If so, use the parameters in file.
In particular, the VeNCrypt and ANONTLS anonymous DH mode need them. By
default a fixed set is used. If you do not want to do that you can specify
"newdh:" to the -vencrypt and -anontls options to
generate a new set each session. If that is too slow for you, use
-dhparams file to a set you created manually via "openssl
dhparam -out file 1024"
-nossl
- Disable the -ssl option (see below). Since
-ssl is off by default -nossl would only be used on the
commandline to unset any *earlier* -ssl option (or
-svc...)
-ssl [pem]
- Use the openssl library (www.openssl.org) to provide a
built-in encrypted SSL/TLS tunnel between VNC viewers and x11vnc. This
requires libssl support to be compiled into x11vnc at build time. If
x11vnc is not built with libssl support it will exit immediately when
-ssl is prescribed. See the -stunnel option below for an
alternative.
- The VNC Viewer-side needs to support SSL/TLS as well. See
this URL and also the discussion below for ideas on how to enable SSL
support for the viewer:
http://www.karlrunge.com/x11vnc/faq.html#faq-ssl-tun nel-viewers . x11vnc
provides an SSL enabled Java viewer applet in the classes/ssl directory
(-http or -httpdir options.) The SSVNC viewer package supports SSL
tunnels too.
- If the VNC Viewer supports VeNCrypt or ANONTLS (vino's
encryption mode) they are also supported by the -ssl mode (see the
-vencrypt and -anontls options for more info; use
-sslonly to disable both of them.)
- Use "-ssl /path/to/mycert.pem" to
specify an SSL certificate file in PEM format to use to identify and
provide a key for this server. See openssl(1) for more info about
PEMs and the -sslGenCert and "-ssl SAVE"
options below for how to create them.
- The connecting VNC viewer SSL tunnel can (at its option)
authenticate this server if it has the public key part of the certificate
(or a common certificate authority, CA, is a more sophisticated way to
verify this server's cert, see -sslGenCA below). This
authentication is done to prevent Man-In-The-Middle attacks. Otherwise, if
the VNC viewer simply accepts this server's key WITHOUT verification, the
traffic is protected from passive sniffing on the network, but *NOT* from
Man-In-The-Middle attacks. There are hacker tools like dsniff/webmitm and
cain that implement SSL Man-In-The-Middle attacks.
- If [pem] is empty or the string "SAVE" then the
openssl(1) command must be available to generate the certificate
the first time. A self-signed certificate is generated (see
-sslGenCA and -sslGenCert for use of a Certificate
Authority.) It will be saved to the file ~/.vnc/certs/server.pem. On
subsequent calls if that file already exists it will be used
directly.
- Use "SAVE_NOPROMPT" to avoid being prompted to
protect the generated key with a passphrase. However in -inetd and
-bg modes there will be no prompting for a passphrase in either
case.
- If [pem] is "SAVE_PROMPT" the server.pem
certificate will be created based on your answers to its prompts for all
info such as OrganizationalName, CommonName, etc.
- Use "SAVE-<string>" and
"SAVE_PROMPT-<string>" to refer to the file
~/.vnc/certs/server-<string>.pem instead (it will be generated if it
does not already exist). E.g. "SAVE-charlie" will store to the
file ~/.vnc/certs/server-charlie.pem
- Examples: x11vnc -ssl SAVE -display :0 ...
x11vnc -ssl SAVE-someother -display :0 ...
- If [pem] is "TMP" and the openssl(1)
utility command exists in PATH, then a temporary, self-signed certificate
will be generated for this session. If openssl(1) cannot be used to
generate a temporary certificate x11vnc exits immediately. The temporary
cert will be discarded when x11vnc exits.
- If successful in using openssl(1) to generate a
temporary certificate in "SAVE" or "TMP" creation
modes, the public part of it will be displayed to stderr (e.g. one could
copy it to the client-side to provide authentication of the server to VNC
viewers.)
- NOTE: In "TMP" mode, unless you safely copy the
public part of the temporary Cert to the viewer for authenticate *every
time* (unlikely...), then only passive sniffing attacks are prevented and
you are still open to Man-In-The-Middle attacks. This is why the default
"SAVE" mode is preferred (and more sophisticated CA mode too).
Only with saved keys AND the VNC viewer authenticating them (via the
public certificate), are Man-In-The-Middle attacks prevented.
- If [pem] is "ANON" then the Diffie-Hellman
anonymous key exchange method is used. In this mode there are *no* SSL
certificates and so it is not possible to authenticate either the VNC
server or VNC client. Thus only passive network sniffing attacks are
avoided: the "ANON" method is susceptible to Man-In-The-Middle
attacks. "ANON" is not recommended; instead use a SSL PEM you
created or the default "SAVE" method.
- See -ssldir below to use a directory besides the
default ~/.vnc/certs
- If your x11vnc binary was not compiled with OpenSSL library
support, use of the -ssl option will induce an immediate failure
and exit. For such binaries, consider using the -stunnel option for
SSL encrypted connections.
- Misc Info: In temporary cert creation mode "TMP",
set the env. var. X11VNC_SHOW_TMP_PEM=1 to have x11vnc print out the
entire certificate, including the PRIVATE KEY part, to stderr. There are
better ways to get/save this info. See "SAVE" above and "
-sslGenCert" below.
-ssltimeout n
- Set SSL read timeout to n seconds. In some situations (i.e.
an iconified viewer in Windows) the viewer stops talking and the
connection is dropped after the default timeout (25s for about the first
minute, 43200s later). Set to zero to poll forever. Set to a negative
value to use the builtin setting.
- Note that this value does NOT apply to the *initial* ssl
init connection. The default timeout for that is 20sec. Use -env
SSL_INIT_TIMEOUT=n to modify it.
-sslnofail
- Exit at the first SSL connection failure. Useful when
scripting SSL connections (e.g. x11vnc is started via ssh) and you do not
want x11vnc waiting around for more connections, tying up ports, etc.
-ssldir dir
- Use dir as an alternate ssl certificate and key
management toplevel directory. The default is ~/.vnc/certs
- This directory is used to store server and other
certificates and keys and also other materials. E.g. in the simplest case,
" -ssl SAVE" will store the x11vnc server cert in
dir/server.pem
- Use of alternate directories via -ssldir allows you
to manage multiple VNC Certificate Authority (CA) keys. Another use is if
~/.vnc/cert is on an NFS share you might want your certificates and keys
to be on a local filesystem to prevent network snooping (for example
-ssldir /var/lib/x11vnc-certs).
- -ssldir affects nearly all of the other -ssl*
options, e.g. -ssl SAVE, -sslGenCert, etc..
-sslverify path
- For either of the -ssl or -stunnel modes, use
path to provide certificates to authenticate incoming VNC *Client*
connections (normally only the server is authenticated in SSL.) This can
be used as a method to replace standard password authentication of
clients.
- If path is a directory it contains the client (or
CA) certificates in separate files. If path is a file, it contains one or
more certificates. See special tokens below. These correspond to the
"CApath = dir" and "CAfile = file" stunnel options.
See the stunnel(8) manpage for details.
- Examples: x11vnc -ssl -sslverify ~/my.crt
x11vnc -ssl -sslverify ~/my_pem_dir/
- Note that if path is a directory, it must contain the certs
in separate files named like <HASH>.0, where the value of
<HASH> is found by running the command "openssl x509
-hash -noout -in file.crt". Evidently one uses
<HASH>.1 if there is a collision...
- The the key-management utility "-sslCertInfo
HASHON" and " -sslCertInfo HASHOFF"
will create/delete these hashes for you automatically (via symlink) in the
HASH subdirs it manages. Then you can point -sslverify to the HASH
subdir.
- Special tokens: in -ssl mode, if path is not
a file or a directory, it is taken as a comma separated list of tokens
that are interpreted as follows:
- If a token is "CA" that means load the
CA/cacert.pem file from the ssl directory. If a token is
"clients" then all the files clients/*.crt in the ssl directory
are loaded. Otherwise the file clients/token.crt is attempted to be
loaded. As a kludge, use a token like ../server-foo to load a server cert
if you find that necessary.
- Use -ssldir to use a directory different from the
~/.vnc/certs default.
- Note that if the "CA" cert is loaded you do not
need to load any of the certs that have been signed by it. You will need
to load any additional self-signed certs however.
- Examples: x11vnc -ssl -sslverify CA x11vnc
-ssl -sslverify self:fred,self:jim x11vnc -ssl
-sslverify CA,clients
- Usually "-sslverify CA" is the most
effective. See the -sslGenCA and -sslGenCert options below
for how to set up and manage the CA framework.
- NOTE: the following utilities, -sslGenCA,
-sslGenCert, -sslEncKey, -sslCertInfo, and
-sslCRL are provided for completeness, but for casual usage they
are overkill.
- They provide VNC Certificate Authority (CA) key creation
and server / client key generation and signing. So they provide a basic
Public Key management framework for VNC-ing with x11vnc. (note that they
require openssl(1) be installed on the system)
- However, the simplest usage mode, "-ssl
TMP" (where x11vnc automatically generates its own,
self-signed, temporary key and the VNC viewers always accept it, e.g.
accepting via a dialog box) is probably safe enough for most scenarios. CA
management is not needed.
- To protect against Man-In-The-Middle attacks the
"TMP" mode can be improved by using " -ssl
SAVE" (same as " -ssl", i.e. the default) to
have x11vnc create a longer term self-signed certificate, and then
(safely) copy the corresponding public key cert to the desired client
machines (care must be taken the private key part is not stolen; you will
be prompted for a passphrase).
- So keep in mind no CA key creation or management (-sslGenCA
and -sslGenCert) is needed for either of the above two common usage
modes.
- One might want to use -sslGenCA and
-sslGenCert if you had a large number of VNC client and server
workstations. That way the administrator could generate a single CA key
with -sslGenCA and distribute its certificate part to all of the
workstations.
- Next, he could create signed VNC server keys (-sslGenCert
server ...) for each workstation or user that then x11vnc would use to
authenticate itself to any VNC client that has the CA cert.
- Optionally, the admin could also make it so the VNC clients
themselves are authenticated to x11vnc (-sslGenCert client ...) For this
-sslverify would be pointed to the CA cert (and/or self-signed
certs).
- x11vnc will be able to use all of these cert and key files.
On the VNC client side, they will need to be "imported" somehow.
Web browsers have "Manage Certificates" actions as does the Java
applet plugin Control Panel. stunnel can also use these files (see the
ss_vncviewer example script in the FAQ and SSVNC.)
-sslCRL path
- Set the Certificate Revocation Lists (CRL) to path.
This setting applies for both -ssl and -stunnel modes.
- If path is a file, the file contains one or more CRLs in
PEM format. If path is a directory, it contains hash named files of CRLs
in the usual OpenSSL manner. See the OpenSSL and stunnel(8)
documentation for more info.
- This option only applies if -sslverify has been
supplied: it checks for revocation along the certificate chain used to
verify the VNC client. The -sslCRL setting will be ignored when
-sslverify is not specified.
- Note that if a CRL's expiration date has passed, all SSL
connections will fail regardless of if they are related to the subject of
the CRL or not.
- Only rarely will one's x11vnc -ssl infrastructure be
so large that this option would be useful (since normally maintaining the
contents of the -sslverify file or directory should be enough.)
However, when using x11vnc with a Certificate Authority (see
-sslGenCA) to authenticate Clients via SSL/TLS, the -sslCRL
option can be useful to revoke users' certs whose private SSL keys were
lost or stolen (e.g. laptop.) This way a new CA cert+key does not need to
be created and new signed client keys generated and distributed to all
users.
- To create a CRL file with revoked certificates the commands
'openssl ca -revoke ...' and 'openssl ca -gencrl ...' are
useful. (Run them in ~/.vnc/certs)
-sslGenCA [dir]
- Generate your own Certificate Authority private key,
certificate, and other files in directory [dir]. x11vnc then exits.
- If [dir] is not supplied, a -ssldir setting is used,
or otherwise ~/.vnc/certs is used.
- This command also creates directories where server and
client certs and keys will be stored. The openssl(1) program must
be installed on the system and available in PATH.
- After the CA files and directories are created the x11vnc
command exits; the VNC server is not run.
- You will be prompted for information to put into the CA
certificate. The info does not have to be accurate just as long as clients
accept the cert for VNC connections. You will also need to supply a
passphrase of at least 4 characters for the CA private key.
- Once you have generated the CA you can distribute its
certificate part, [dir]/CA/cacert.pem, to other workstations where VNC
viewers will be run. One will need to "import" this certificate
in the applications, e.g. Web browser, Java applet plugin, stunnel, etc.
Next, you can create and sign keys using the CA with the
-sslGenCert option below.
- Examples: x11vnc -sslGenCA x11vnc -sslGenCA
~/myCAdir x11vnc -ssldir ~/myCAdir -sslGenCA
- (the last two lines are equivalent)
-sslGenCert type name
- Generate a VNC server or client certificate and private key
pair signed by the CA created previously with -sslGenCA. The
openssl(1) program must be installed on the system and available in
PATH.
- After the Certificate is generated x11vnc exits; the VNC
server is not run.
- The type of key to be generated is the string type.
It is either "server" (i.e. for use by x11vnc) or
"client" (for a VNC viewer). Note that typically only
"server" is used: the VNC clients authenticate themselves by a
non-public-key method (e.g. VNC or unix password). type is
required.
- An arbitrary default name you want to associate with the
key is supplied by the name string. You can change it at the
various prompts when creating the key. name is optional.
- If name is left blank for clients keys then
"nobody" is used. If left blank for server keys, then the
primary server key: "server.pem" is created (this is the saved
one referenced by " -ssl SAVE" when the server is
started)
- If name begins with the string "self:"
then a self-signed certificate is created instead of one signed by your CA
key.
- If name begins with the string "req:" then
only a key (.key) and a certificate signing *request* (.req) are
generated. You can then send the .req file to an external CA (even a
professional one, e.g. Thawte) and then combine the .key and the received
cert into the .pem file with the same basename.
- The distinction between "server" and
"client" is simply the choice of output filenames and
sub-directory. This makes it so the -ssl SAVE-name option can
easily pick up the x11vnc PEM file this option generates. And similarly
makes it easy for the -sslverify option to pick up your client
certs.
- There is nothing special about the filename or directory
location of either the "server" and "client" certs.
You can rename the files or move them to wherever you like.
- Precede this option with -ssldir [dir] to use a
directory other than the default ~/.vnc/certs You will need to run
-sslGenCA on that directory first before doing any
-sslGenCert key creation.
- Note you cannot recreate a cert with exactly the same
distiguished name (DN) as an existing one. To do so, you will need to edit
the [dir]/CA/index.txt file to delete the line.
- Similar to -sslGenCA, you will be prompted to fill
in some information that will be recorded in the certificate when it is
created.
- Tip: if you know the fully-qualified hostname other people
will be connecting to, you can use that as the CommonName "CN"
to avoid some applications (e.g. web browsers and java plugin) complaining
that it does not match the hostname.
- You will also need to supply the CA private key passphrase
to unlock the private key created from -sslGenCA. This private key
is used to sign the server or client certificate.
- The "server" certs can be used by x11vnc directly
by pointing to them via the -ssl [pem] option. The default file
will be ~/.vnc/certs/server.pem. This one would be used by simply typing
-ssl SAVE. The pem file contains both the certificate and the
private key. server.crt file contains the cert only.
- The "client" cert + private key file will need to
be copied and imported into the VNC viewer side applications (Web browser,
Java plugin, stunnel, etc.) Once that is done you can delete the
"client" private key file on this machine since it is only
needed on the VNC viewer side. The, e.g.
~/.vnc/certs/clients/<name>.pem contains both the cert and private
key. The <name>.crt contains the certificate only.
- NOTE: It is very important to know one should generate new
keys with a passphrase. Otherwise if an untrusted user steals the key file
he could use it to masquerade as the x11vnc server (or VNC viewer client).
You will be prompted whether to encrypt the key with a passphrase or not.
It is recommended that you do. One inconvenience to a passphrase is that
it must be typed in EVERY time x11vnc or the client app is started
up.
- Examples:
- x11vnc -sslGenCert server x11vnc -ssl SAVE
-display :0 ...
- and then on viewer using ss_vncviewer stunnel wrapper (see
the FAQ): ss_vncviewer -verify ./cacert.crt hostname:0
- (this assumes the cacert.crt cert from -sslGenCA was
safely copied to the VNC viewer machine where ss_vncviewer is run)
- Example using a name:
- x11vnc -sslGenCert server charlie x11vnc -ssl
SAVE-charlie -display :0 ...
- Example for a client certificate (rarely used):
- x11vnc -sslGenCert client roger scp
~/.vnc/certs/clients/roger.pem somehost:. rm
~/.vnc/certs/clients/roger.pem
- x11vnc is then started with the option -sslverify
~/.vnc/certs/clients/roger.crt (or simply -sslverify roger), and on
the viewer user on somehost could do for example:
- ss_vncviewer -mycert ./roger.pem hostname:0
- If you set the env. var REQ_ARGS='...' it will be passed to
openssl req(1). A common use would be REQ_ARGS='-days 1095' to bump
up the expiration date (3 years in this case).
-sslEncKey pem
- Utility to encrypt an existing PEM file with a passphrase
you supply when prompted. For that key to be used (e.g. by x11vnc) the
passphrase must be supplied each time.
- The "SAVE" notation described under -ssl
applies as well. (precede this option with -ssldir [dir] to refer a
directory besides the default ~/.vnc/certs)
- The openssl(1) program must be installed on the
system and available in PATH. After the Key file is encrypted the x11vnc
command exits; the VNC server is not run.
- Examples: x11vnc -sslEncKey /path/to/foo.pem x11vnc
-sslEncKey SAVE x11vnc -sslEncKey SAVE-charlie
-sslCertInfo pem
- Prints out information about an existing PEM file. In
addition the public certificate is also printed. The openssl(1)
program must be in PATH. Basically the command "openssl x509
-text" is run on the pem.
- After the info is printed the x11vnc command exits; the VNC
server is not run.
- The "SAVE" notation described under -ssl
applies as well.
- Using "LIST" will give a list of all certs being
managed (in the ~/.vnc/certs dir, use -ssldir to refer to another
dir). "ALL" will print out the info for every managed key (this
can be very long). Giving a client or server cert shortname will also try
a lookup (e.g. -sslCertInfo charlie). Use "LISTL" or
"LL" for a long (ls -l style) listing.
- Using "HASHON" will create subdirs [dir]/HASH and
[dir]/HASH with OpenSSL hash filenames (e.g. 0d5fbbf1.0) symlinks pointing
up to the corresponding *.crt file. ([dir] is ~/.vnc/certs or one given by
-ssldir.) This is a useful way for other OpenSSL applications (e.g.
stunnel) to access all of the certs without having to concatenate them.
x11vnc will not use them unless you specifically reference them.
"HASHOFF" removes these HASH subdirs.
- The LIST, LISTL, LL, ALL, HASHON, HASHOFF words can also be
lowercase, e.g. "list".
-sslDelCert pem
- Prompts you to delete all .crt .pem .key .req files
associated with [pem]. x11vnc then exits. "SAVE" and lookups as
in -sslCertInfo apply as well.
-sslScripts
- Prints out both the 'genCA' and 'genCert' x11vnc openssl
wrapper scripts for you to examine, modify, etc. The scripts are printed
to stdout and then the x11vnc program exits.
-stunnel [pem]
- Use the stunnel(8) (stunnel.mirt.net) to provide an
encrypted SSL tunnel between viewers and x11vnc.
- This external tunnel method was implemented prior to the
integrated -ssl encryption described above. It still works well and
avoids the requirement of linking with the OpenSSL libraries. This mode
requires stunnel to be installed on the system and available via PATH
(n.b. stunnel is often installed in sbin directories). Version 4.x of
stunnel is assumed (but see -stunnel3 below.)
- [pem] is optional, use "-stunnel
/path/to/stunnel.pem" to specify a PEM certificate file to
pass to stunnel. See the -ssl option for more info on certificate
files.
- Whether or not your stunnel has its own certificate depends
on your stunnel configuration; stunnel often generates one at install
time. See your stunnel documentation for details. In any event, if you
want to use this certificate you must supply the full path to it as [pem].
Note: the file may only be readable by root.
- [pem] may also be the special strings "TMP",
"SAVE", and "SAVE..." as described in the -ssl
option. If [pem] is not supplied, "SAVE" is assumed.
- Note that the VeNCrypt, ANONTLS, and "ANON" modes
are not supported in -stunnel mode.
- stunnel is started up as a child process of x11vnc and any
SSL connections stunnel receives are decrypted and sent to x11vnc over a
local socket. The strings "The SSL VNC desktop is ..." and
"SSLPORT=..." are printed out at startup to indicate this.
- The -localhost option is enforced by default to
avoid people routing around the SSL channel. Use -env
STUNNEL_DISABLE_LOCALHOST=1 to disable this security requirement.
- Set -env STUNNEL_DEBUG=1 for more debugging
printout.
- Set -env STUNNEL_PROG=xxx to the full path of
stunnel program you want to be used (e.g. /usr/bin/stunnel4).
- Set -env STUNNEL_LISTEN=xxx to the address of the
network interface to listen on (the default is to listen on all
interfaces), e.g. STUNNEL_LISTEN=192.168.1.100.
- A simple way to add IPv6 support is STUNNEL_LISTEN=::
- Your VNC viewer will also need to be able to connect via
SSL. Unfortunately not too many do this. See the information about SSL
viewers under the -ssl option. The x11vnc project's SSVNC is an
option.
- Also, in the x11vnc distribution, patched TightVNC and
UltraVNC Java applet jar files are provided in the classes/ssl directory
that do SSL connections. Enable serving them with the -http,
-http_ssl, or -httpdir (see the option descriptions for more
info.)
- Note that for the Java viewer applet usage the
"?PORT=xxxx" in the various URLs printed at startup will need to
be supplied to the web browser to connect properly.
- Currently the automatic "single port" HTTPS mode
of -ssl is not fully supported in -stunnel mode. However, it
can be emulated via:
- % x11vnc -stunnel -http_ssl
-http_oneport ...
- In general, it is also not too difficult to set up an
stunnel or other SSL tunnel on the viewer side. A simple example on Unix
using stunnel 3.x is:
- % stunnel -c -d localhost:5901 -r
remotehost:5900 % vncviewer localhost:1
- For Windows, stunnel has been ported to it and there are
probably other such tools available. See the FAQ and SSVNC for more
examples.
-stunnel3 [pem]
- Use version 3.x stunnel command line syntax instead of
version 4.x. The -http/-httpdir Java applet serving is currently
not available in this mode.
-enc cipher:keyfile
- Use symmetric encryption with cipher "cipher" and
secret key data in "keyfile". If keyfile is pw=<string>
then "string" is used as the key data.
- NOTE: It is recommended that you use SSL via the
-ssl option instead of this option because SSL is well understood
and takes great care to establish unique session keys and is more
compatible with other software. Use this option if you do not want to deal
with SSL certificates for authentication and do not want to use SSH but
want some encryption for your VNC session. Or if you must interface with a
symmetric key tunnel that you do not have control over.
- Note that this mode will NOT work with the UltraVNC DSM
plugins because they alter the RFB protocol in addition to tunnelling with
the symmetric cipher (an unfortunate choice of implementation...)
- cipher can be one of: arc4, aesv2, aes-cfb, blowfish,
aes256, or 3des. See the OpenSSL documentation for more info. The keysize
is 128 bits (except for aes256). Here is one way to make a keyfile with
that many bits:
- dd if=/dev/random of=./my.key bs=16 count=1
- you will need to securely share this key with the other
side of the VNC connection (See SSVNC for examples).
- Example: -enc blowfish:./my.key Example: -enc
blowfish:pw=swordfish
- By default 16 bytes of random salt followed by 16 bytes of
random initialization vector are sent at the very beginning of the stream.
The other side must read these and initialize their cipher with them.
These values make the session key unique (without them the security is
minimal). Similarly, the other side must send us its random salt and IV
with those same lengths.
- The salt and key data are combined to create a session key
using an md5 hash as described in EVP_BytesToKey(3).
- The exact call is: EVP_BytesToKey(Cipher, EVP_md5(), salt,
keydata, len, 1, keystr, NULL); where salt is the random data as described
above, and keydata is the shared secret key data. keystr is the resulting
session key. The cipher is then seeded with keystr and uses the random
initialization vector as its first block.
- To modify the amount of random salt and initialization
vector use cipher@n,m where n is the salt length and m the initialization
vector length. E.g.
- -enc aes-cfb@8,16:./my.key
- It is not a good idea to set either one to zero, although
you may be forced to if the other side of the tunnel is not under your
control.
- To skip the salt and EVP_BytesToKey MD5 entirely (no
hashing is done: the keydata is directly inserted into the cipher) specify
"-1" for the salt, e.g.
- -enc blowfish@-1,16:./my.key
- The message digest can also be changed to something besides
the default MD5. Use cipher@md+n,m where "md" can be one of sha,
sha1, md5, or ripe. For example:
- -enc arc4@sha+8,16:./my.key
- The SSVNC vnc viewer project supplies a symmetric
encryption tool named "ultravnc_dsm_helper" that can be used on
the viewer side. For example:
- ssvncviewer exec='ultravnc_dsm_helper arc4 my.key 0
h:p'
- (or replace 'ssvncviewer' with 'ssvnc -viewer')
where h:p is the hostname and port of the x11vnc server.
ultravnc_dsm_helper may also be used standalone to provide a symmetric
encryption tunnel for any viewer or server (VNC or otherwise.) The cipher
(1st arg) is basically the same syntax as we use above.
- Also see the 'Non-Ultra DSM' SSVNC option for the
´UltraVNC DSM Encryption Plugin' advanced option.
- For both ways of using the viewer, you can specify the
salt,ivec sizes (in GUI or, e.g. arc4@8,16).
-https [port]
- Use a special, separate HTTPS port (-ssl and
-stunnel modes only) for HTTPS Java viewer applet downloading. I.e.
not 5900 and not 5800 (the defaults.)
- BACKGROUND: In -ssl mode, it turns out you can use
the single VNC port (e.g. 5900) for both VNC and HTTPS connections. (HTTPS
is used to retrieve a SSL-aware VncViewer.jar applet that is provided with
x11vnc). Since both use SSL the implementation was extended to detect if
HTTP traffic (i.e. GET) is taking place and handle it accordingly. The URL
would be, e.g.:
- https://mymachine.org:5900/
- This is convenient for firewalls, etc, because only one
port needs to be allowed in. However, this heuristic adds a few seconds
delay to each connection and can be unreliable (especially if the user
takes much time to ponder the Certificate dialogs in his browser, Java VM,
or VNC Viewer applet. That's right 3 separate "Are you sure you want
to connect?" dialogs!)
- END OF BACKGROUND.
- USAGE: So use the -https option to provide a
separate, more reliable HTTPS port that x11vnc will listen on. If [port]
is not provided (or is 0), one is autoselected. The URL to use is printed
out at startup.
- The SSL Java applet directory is specified via the
-httpdir option. If not supplied, -https will try to guess
the directory as though the -http option was supplied.
-httpsredir [port]
- In -ssl mode with the Java applet retrieved via
HTTPS, when the HTML file containing applet parameters ('index.vnc' or
'proxy.vnc') is sent do NOT set the applet PORT parameter to the actual
VNC port but set it to "port" instead. If "port" is
not supplied, then the port number is guessed from the Host: HTTP
header.
- This is useful when an incoming TCP connection redirection
is performed by a router/gateway/firewall from one port to an internal
machine where x11vnc is listening on a different port. The Java applet
needs to connect to the firewall/router port, not the VNC port on the
internal workstation. For example, one could redir from mygateway.com:443
to workstation:5900.
- This spares the user from having to type in
https://mygateway.com/?PORT=443 into their web browser. Note that port 443
is the default https port; other ports must be explicitly indicated, for
example: https://mygateway.com:8000/?PORT=8000. To avoid having to include
the PORT= in the browser URL, simply supply "
-httpsredir" to x11vnc.
- This option does not work in -stunnel mode.
- More tricks: set the env var X11VNC_EXTRA_HTTPS_PARAMS to
be extra URL parameters to use. This way you do not need to specify extra
PARAMS in the index.vnc file. E.g. x11vnc -env
X11VNC_EXTRA_HTTPS_PARAMS='?GET=1' ...
- If you do not want to expose the non-SSL HTTP port to the
network (i.e. you just want the single VNC/HTTPS port, e.g. 5900, open for
connections) then specify the option -env
X11VNC_HTTP_LISTEN_LOCALHOST=1 This way the connection to the LibVNCServer
httpd server will only be available on localhost (note that in -ssl
mode, HTTPS requests are redirected from SSL to the non-SSL LibVNCServer
HTTP server.)
-http_oneport
- For UN-encrypted connections mode (i.e. no -ssl,
-stunnel, or -enc options), allow the Java VNC Viewer applet
to be downloaded thru the VNC port via HTTP.
- That is to say, you can use a single port for Java applet
viewer connections by using a URL in your web browser like this, for
example:
- http://hostname:5900
- The regular, two-port mode, URL http://hostname:5800 will
continue to work as well.
- As mentioned above, this mode will NOT work with the
-ssl, -stunnel, or -enc encryption options. Note that
is it equivalent to '-enc none' (i.e. it uses the same detection mechanism
as for HTTPS, but with no encryption.)
- HTTPS single-port is on by default in -ssl encrypted
mode (and -enc too), so you only need -http_oneport when
doing non-SSL encrypted connections.
- This mode could also be useful for SSH tunnels since it
means only one port needs to be redirected.
- The -httpsredir option may also be useful for this
mode when using an SSH tunnel as well as for router port
redirections.
- Note that the -env X11VNC_HTTP_LISTEN_LOCALHOST=1
option described above under -httpsredir applies for the
LibVNCServer httpd server in all cases (ssl or not.)
-ssh user@host:disp
- Create a remote listening port on machine "host"
via a SSH tunnel using the -R rport:localhost:lport method. lport
will be the local x11vnc listening port, so a connection to rport
(5900+disp) on "host" will reach x11vnc. E.g.
fred@snoopy.com:0
- This could be useful if a firewall/router prevents incoming
connections to the x11vnc machine, but the ssh machine "host"
can be reached by the VNC viewer. "user@" is not needed unless
the remote unix username differs from the current one.
- By default the remote sshd is usually configured to listen
only on localhost for rport, so the viewer may need to ssh -L redir
to "host" as well (See SSVNC to automate this). The sshd setting
GatewayPorts enables listening on all interfaces for rport; viewers can
reach it more easily.
- "disp" is the VNC display for the remote SSH
side, e.g. 0 corresponds to port 5900, etc. If disp is greater than 200
the value is used as the port. Use a negative value to force a low port,
e.g. host:-80 will use port 80.
- If ssh-agent is not active, then the ssh password needs to
be entered in the terminal where x11vnc is running.
- By default the remote ssh will issue a 'sleep 300' to wait
for the incoming connection for 5 mins. To modify this use
user@host:disp+secs.
- If the remote SSH server is on a non-standard port (i.e.
not 22) use user@host:port:disp+secs.
- Note that the ssh process MAY NOT be killed when x11vnc
exits. It tries by looking at ps(1) output.
-users list
- If x11vnc is started as root (say from inetd(8) or
from display managers xdm(1) , gdm(1) , etc), then as soon
as possible after connections to the X display are established try to
switch to one of the users in the comma separated list. If x11vnc
is not running as root this option is ignored.
- Why use this option? In general it is not needed since
x11vnc is already connected to the X display and can perform its primary
functions. The option was added to make some of the *external* utility
commands x11vnc occasionally runs work properly. In particular under GNOME
and KDE to implement the " -solid color" feature
external commands (gconftool-2 and dcop) unfortunately must be run as the
user owning the desktop session. Since this option switches userid it also
affects the userid used to run the processes for the -accept and
-gone options. It also affects the ability to read files for
options such as -connect, -allow, and -remap and also
the ultra and tight filetransfer feature if enabled. Note that the
-connect file is also sometimes written to.
- So be careful with this option since in some situations its
use can decrease security.
- In general the switch to a user will only take place if the
display can still be successfully opened as that user (this is primarily
to try to guess the actual owner of the session). Example: "
-users fred,wilma,betty". Note that a malicious local
user "barney" by quickly using "xhost +" when logging
in may possibly get the x11vnc process to switch to user "fred".
What happens next?
- Under display managers it may be a long time before the
switch succeeds (i.e. a user logs in). To instead make it switch
immediately regardless if the display can be reopened prefix the username
with the "+" character. E.g. " -users
+bob" or " -users +nobody".
- The latter (i.e. switching immediately to user
"nobody") is the only obvious use of the -users option
that increases security.
- Use the following notation to associate a group with a
user: user1.group1,user2.group2,... Note that initgroups(2) will
still be called first to try to switch to ALL of a user's groups (primary
and additional groups). Only if that fails or it is not available then the
single group specified as above (or the user's primary group if not
specified) is switched to with setgid(2). Use -env
X11VNC_SINGLE_GROUP=1 to prevent trying initgroups(2) and only
switch to the single group. This sort of setting is only really needed to
make the ultra or tight filetransfer permissions work properly. This
format applies to any comma separated list of users, even the special
"=" modes described below.
- In -unixpw mode, if "-users
unixpw=" is supplied then after a user authenticates himself
via the -unixpw mechanism, x11vnc will try to switch to that user
as though " -users +username" had been supplied.
If you want to limit which users this will be done for, provide them as a
comma separated list after "unixpw=" Groups can also be
specified as described above.
- Similarly, in -ssl mode, if "-users
sslpeer=" is supplied then after an SSL client authenticates
with his cert (the -sslverify option is required for this) x11vnc
will extract a UNIX username from the "emailAddress" field
(username@hostname.com) of the "Subject" of the x509 SSL cert
and then try to switch to that user as though " -users
+username" had been supplied. If you want to limit which users
this will be done for, provide them as a comma separated list after
"sslpeer=". Set the env. var X11VNC_SSLPEER_CN to use the Common
Name (normally a hostname) instead of the Email field.
- NOTE: for sslpeer= mode the x11vnc administrator must take
care that any client certs he adds to -sslverify have the intended
UNIX username in the "emailAddress" field of the cert. Otherwise
a user may be able to log in as another. This command can be of use in
checking: "openssl x509 -text -in file.crt", see
the "Subject:" line. Also, along with the normal RFB_* env.
vars. (see -accept) passed to external cmd= commands,
RFB_SSL_CLIENT_CERT will be set to the client's x509 certificate
string.
- The sslpeer= mode can aid finding X sessions via the
FINDDISPLAY and FINDCREATEDISPLAY mechanisms.
- To immediately switch to a user *before* connections to the
X display are made or any files opened use the "=" character:
" -users =bob". That user needs to be able to open
the X display and any files of course.
- The special user "guess=" means to examine the
utmpx database (see who(1) ) looking for a user attached to the
display number (from DISPLAY or -display option) and try him/her.
To limit the list of guesses, use: " -users
guess=bob,betty".
- Even more sinister is the special user "lurk="
that means to try to guess the DISPLAY from the utmpx login database as
well. So it "lurks" waiting for anyone to log into an X session
and then connects to it. Specify a list of users after the = to limit
which users will be tried. To enable a different searching mode, if the
first user in the list is something like ":0" or
":0-2" that indicates a range of DISPLAY numbers that will be
tried (regardless of whether they are in the utmpx database) for all users
that are logged in. Also see the " -display
WAIT:..." functionality. Examples: " -users
lurk=" and also " -users
lurk=:0-1,bob,mary"
- Be especially careful using the "guess=" and
"lurk=" modes. They are not recommended for use on machines with
untrustworthy local users.
-noshm
- Do not use the MIT-SHM extension for the polling. Remote
displays can be polled this way: be careful this can use large amounts of
network bandwidth. This is also of use if the local machine has a limited
number of shm segments and -onetile is not sufficient.
-flipbyteorder
- Sometimes needed if remotely polled host has different
endianness. Ignored unless -noshm is set.
-onetile
- Do not use the new copy_tiles() framebuffer mechanism, just
use 1 shm tile for polling. Limits shm segments used to 3.
- To disable any automatic shm reduction set the env. var.
X11VNC_NO_LIMIT_SHM.
-solid [color]
- To improve performance, when VNC clients are connected try
to change the desktop background to a solid color. The [color] is
optional: the default color is "cyan4". For a different one
specify the X color (rgb.txt name, e.g. "darkblue" or numerical
"#RRGGBB").
- Currently this option only works on GNOME, KDE, CDE, XFCE,
and classic X (i.e. with the background image on the root window). The
"gconftool-2", "dcop" and "xfconf-query"
external commands are run for GNOME, KDE, and XFCE respectively. This also
works on native MacOSX. (There is no color selection for MacOSX or XFCE.)
Other desktops won't work, (send us the corresponding commands if you find
them). If x11vnc is running as root ( inetd(8) or gdm(1) ),
the -users option may be needed for GNOME, KDE, XFCE. If x11vnc
guesses your desktop incorrectly, you can force it by prefixing color with
"gnome:", "kde:", "cde:", "xfce:",
or "root:".
- Update: -solid no longer works on KDE4.
- This mode works in a limited way on the Mac OS X Console
with one color ('kelp') using the screensaver writing to the background.
Look in "~/Library/Screen Savers" for VncSolidColor.png to
change the color.
-blackout string
- Black out rectangles on the screen. string is a
comma separated list of WxH+X+Y type geometries for each rectangle. If one
of the items on the list is the string "noptr" the mouse pointer
will not be allowed to go into a blacked out region.
-xinerama, -noxinerama
- If your screen is composed of multiple monitors glued
together via XINERAMA, and that screen is not a rectangle this option will
try to guess the areas to black out (if your system has libXinerama).
default: -xinerama
- In general, we have noticed on XINERAMA displays you may
need to use the " -xwarppointer" option if the mouse
pointer misbehaves and it is enabled by default. Use "
-noxwarppointer" if you do not want this.
-xtrap
- Use the DEC-XTRAP extension for keystroke and mouse input
insertion. For use on legacy systems, e.g. X11R5, running an incomplete or
missing XTEST extension. By default DEC-XTRAP will be used if XTEST server
grab control is missing, use -xtrap to do the keystroke and mouse
insertion via DEC-XTRAP as well.
-xrandr [mode]
- If the display supports the XRANDR (X Resize, Rotate and
Reflection) extension, and you expect XRANDR events to occur to the
display while x11vnc is running, this options indicates x11vnc should try
to respond to them (as opposed to simply crashing by assuming the old
screen size). See the xrandr(1) manpage and run ´xrandr
-q' for more info. [mode] is optional and described below.
- Since watching for XRANDR events and trapping errors
increases polling overhead, only use this option if XRANDR changes are
expected. For example on a rotatable screen PDA or laptop, or using a
XRANDR-aware Desktop where you resize often. It is best to be viewing with
a vncviewer that supports the NewFBSize encoding, since it knows how to
react to screen size changes. Otherwise, LibVNCServer tries to do so
something reasonable for viewers that cannot do this (portions of the
screen may be clipped, unused, etc).
- Note: the default now is to check for XRANDR events, but do
not trap every X call that may fail due to resize. If a resize event is
received, the full -xrandr mode is enabled. To disable even
checking for events supply: -noxrandr.
- "mode" defaults to "resize", which
means create a new, resized, framebuffer and hope all viewers can cope
with the change. "newfbsize" means first disconnect all viewers
that do not support the NewFBSize VNC encoding, and then resize the
framebuffer. "exit" means disconnect all viewer clients, and
then terminate x11vnc.
-rotate string
- Rotate and/or flip the framebuffer view exported by VNC.
This transformation is independent of XRANDR and is done in software in
main memory and so may be slower. This mode could be useful on a handheld
with portrait or landscape modes that do not correspond to the scanline
order of the actual framebuffer. string can be:
- x flip along x-axis y flip along y-axis xy flip along x-
and y-axes +90 rotate 90 degrees clockwise -90 rotate 90 degrees
counter-clockwise +90x rotate 90 degrees CW, then flip along x +90y rotate
90 degrees CW, then flip along y
- these give all possible rotations and reflections.
- Aliases: same as xy: yx, +180, -180, 180 same as
-90: +270, 270 same as +90: 90, (ditto for 90x, 90y)
- Like -scale, this transformation is applied at the
very end of any chain of framebuffer transformations and so any options
with geometries, e.g. -blackout, -clip, etc. are relative to
the original X (or -rawfb) framebuffer, not the final one sent to
VNC viewers.
- If you do not want the cursor shape to be rotated prefix
string with "nc:", e.g. "nc:+90",
"nc:xy", etc.
-padgeom WxH
- Whenever a new vncviewer connects, the framebuffer is
replaced with a fake, solid black one of geometry WxH. Shortly afterwards
the framebuffer is replaced with the real one. This is intended for use
with vncviewers that do not support NewFBSize and one wants to make sure
the initial viewer geometry will be big enough to handle all subsequent
resizes (e.g. under -xrandr, -remote id:windowid, rescaling,
etc.)
- In -unixpw mode this sets the size of the login
screen. Use "once:WxH" it ignore padgeom after the login screen
is set up.
-o logfile
- Write stderr messages to file logfile instead of to
the terminal. Same as " -logfile file". To append
to the file use " -oa file" or
"-logappend file". If logfile contains the
string "%VNCDISPLAY" it is expanded to the vnc display (the name
may need to be guessed at.) "%HOME" works too.
-flag file
- Write the "PORT=NNNN" (e.g. PORT=5900) string to
file in addition to stdout. This option could be useful by wrapper
script to detect when x11vnc is ready.
-rmflag file
- Remove file at exit to signal when x11vnc is done.
The file is created at startup if it does not already exist or if
file is prefixed with "create:". If the file is created,
the x11vnc PID is placed in the file. Otherwise the files contents is not
changed. Use prefix "nocreate:" to prevent creation.
-rc filename
- Use filename instead of $HOME/.x11vncrc for rc
file.
-norc
- Do not process any .x11vncrc file for options.
-env VAR=VALUE
- Set the environment variable 'VAR' to value 'VALUE' at
x11vnc startup. This is a convenience utility to avoid shell script
wrappers, etc. to set the env. var. You may specify as many of these as
needed on the command line.
-prog /path/to/x11vnc
- Set the full path to the x11vnc program for cases when it
cannot be determined from argv[0] (e.g. tcpd/inetd)
-h, -help
- Print this help text. -?, -opts Only list the x11vnc
options.
-V, -version
- Print program version and last modification date.
-license
- Print out license information. Same as -copying and
-warranty.
-dbg
- Instead of exiting after cleaning up, run a simple
"debug crash shell" when fatal errors are trapped.
-q, -quiet
- Be quiet by printing less informational output to stderr.
(use -noquiet to undo an earlier -quiet.)
- The -quiet option does not eliminate all
informational output, it only reduces it. It is ignored in most auxiliary
usage modes, e.g. -storepasswd. To eliminate all output use:
2>/dev/null 1>&2, etc.
-v, -verbose
- Print out more information to stderr.
-bg
- Go into the background after screen setup. Messages to
stderr are lost unless -o logfile is used. Something like this
could be useful in a script:
- port=`ssh -t $host "x11vnc -display :0 -bg" |
grep PORT`
- port=`echo "$port" | sed -e 's/PORT=//'`
- port=`expr $port - 5900`
- vncviewer $host:$port
-modtweak, -nomodtweak
- Option -modtweak automatically tries to adjust the
AltGr and Shift modifiers for differing language keyboards between client
and host. Otherwise, only a single key press/release of a Keycode is
simulated (i.e. ignoring the state of the modifiers: this usually works
for identical keyboards). Also useful in resolving cases where a Keysym is
bound to multiple keys (e.g. "<" + ">" and
"," + "<" keys). Default: -modtweak
- If you are having trouble with with keys and -xkb or
-noxkb, and similar things don't help, try -nomodtweak.
- On some HP-UX systems it is been noted that they have an
odd keymapping where a single keycode will have a keysym, e.g.
"#", up to three times. You can check via "xmodmap
-pk" or the -dk option. The failure is when you try to
type "#" it yields "3". If you see this problem try
setting the environment variable MODTWEAK_LOWEST=1 to see if it
helps.
-xkb, -noxkb
- When in modtweak mode, use the XKEYBOARD extension (if the
X display supports it) to do the modifier tweaking. This is powerful and
should be tried if there are still keymapping problems when using
-modtweak by itself. The default is to check whether some common
keysyms, e.g. !, @, [, are only accessible via -xkb mode and if so
then automatically enable the mode. To disable this automatic detection
use -noxkb.
- When -xkb mode is active you can set these env.
vars. They apply only when there is ambiguity as to which key to choose
(i.e the mapping is not one-to-one). NOKEYHINTS=1: for up ascii keystrokes
do not use score hints saved when the key was pressed down. NOANYDOWN=1:
for up keystrokes do not resort to searching through keys that are
currently pressed down. KEYSDOWN=N: remember the last N keys press down
for tie-breaking when an up keystroke comes in.
-capslock
- When in -modtweak (the default) or -xkb mode,
if a keysym in the range A-Z comes in check the X server to see if the
Caps_Lock is set. If it is do not artificially press Shift to generate the
keysym. This will enable the CapsLock key to behave correctly in some
circumstances: namely *both* the VNC viewer machine and the x11vnc X
server are in the CapsLock on state. If one side has CapsLock on and the
other off and the keyboard is not behaving as you think it should you
should correct the CapsLock states (hint: pressing CapsLock inside and
outside of the viewer can help toggle them both to the correct state).
However, for best results do not use this option, but rather *only* enable
CapsLock on the VNC viewer side (i.e. by pressing CapsLock outside of the
viewer window, also -skip_lockkeys below). Also try
-nomodtweak for a possible workaround.
-skip_lockkeys, -noskip_lockkeys
- Have x11vnc ignore all Caps_Lock, Shift_Lock, Num_Lock,
Scroll_Lock keysyms received from viewers. The idea is you press Caps_Lock
on the VNC Viewer side but that does not change the lock state in the
x11vnc-side X server. Nevertheless your capitalized letters come in over
the wire and are applied correctly to the x11vnc-side X server. Note this
mode probably won't do what you want in -nomodtweak mode. Also, a
kludge for KP_n digits is always done in this mode: they are mapped to
regular digit keysyms. See also -capslock above. The default is
-noskip_lockkeys.
-skip_keycodes string
- Ignore the comma separated list of decimal keycodes.
Perhaps these are keycodes not on your keyboard but your X server thinks
exist. Currently only applies to -xkb mode. Use this option to help
x11vnc in the reverse problem it tries to solve: Keysym -> Keycode(s)
when ambiguities exist (more than one Keycode per Keysym). Run 'xmodmap
-pk' to see your keymapping. Example: " -skip_keycodes
94,114"
-sloppy_keys
- Experimental option that tries to correct some
"sloppy" key behavior. E.g. if at the viewer you press Shift+Key
but then release the Shift before Key that could give rise to extra
unwanted characters (usually only between keyboards of different
languages). Only use this option if you observe problems with some
keystrokes.
-skip_dups, -noskip_dups
- Some VNC viewers send impossible repeated key events, e.g.
key-down, key-down, key-up, key-up all for the same key, or 20 downs in a
row for the same modifier key! Setting -skip_dups means to skip
these duplicates and just process the first event. Note: some VNC viewers
assume they can send down's without the corresponding up's and so you
should not set this option for these viewers (symptom: some keys do not
autorepeat) Default: -noskip_dups
-add_keysyms, -noadd_keysyms
- If a Keysym is received from a VNC viewer and that Keysym
does not exist in the X server, then add the Keysym to the X server's
keyboard mapping on an unused key. Added Keysyms will be removed
periodically and also when x11vnc exits. Default: -add_keysyms
-clear_mods
- At startup and exit clear the modifier keys by sending
KeyRelease for each one. The Lock modifiers are skipped. Used to clear the
state if the display was accidentally left with any pressed down.
-clear_keys
- As -clear_mods, except try to release ANY pressed
key. Note that this option and -clear_mods can interfere with a
person typing at the physical keyboard.
-clear_all
- As -clear_keys, except try to release any CapsLock,
NumLock, etc. locks as well.
-remap string
- Read Keysym remappings from file named string.
Format is one pair of Keysyms per line (can be name or hex value)
separated by a space. If no file named string exists, it is instead
interpreted as this form: key1-key2,key3-key4,... See
<X11/keysymdef.h> header file for a list of Keysym names, or use
xev(1).
- To map a key to a button click, use the fake Keysyms
"Button1", ..., etc. E.g: " -remap
Super_R-Button2" (useful for pasting on a laptop)
- I use these if the machine I am viewing from does not have
a scrollwheel or I don't like using the one it has:
- -remap Super_R-Button4,Menu-Button5 -remap
KP_Add-Button4,KP_Enter-Button5
- the former would be used on a PC, the latter on a MacBook.
This way those little used keys can be used to generate bigger hops than
the Up and Down arrows provide. One can scroll through text or web pages
more quickly this way (especially if x11vnc scroll detection is
active.)
- Use Button44, Button12, etc. for multiple clicks.
- To disable a keysym (i.e. make it so it will not be
injected), remap it to "NoSymbol" or "None".
- Dead keys: "dead" (or silent, mute) keys are keys
that do not produce a character but must be followed by a 2nd keystroke.
This is often used for accenting characters, e.g. to put "`" on
top of "a" by pressing the dead key and then "a". Note
that this interpretation is not part of core X11, it is up to the toolkit
or application to decide how to react to the sequence. The X11 names for
these keysyms are "dead_grave", "dead_acute", etc.
However some VNC viewers send the keysyms "grave",
"acute" instead thereby disabling the accenting. To work around
this -remap can be used. For example " -remap
grave-dead_grave,acute-dead_acute"
- As a convenience, "-remap DEAD"
applies these remaps:
-
g grave-dead_grave
a acute-dead_acute
c asciicircum-dead_circumflex
t asciitilde-dead_tilde
m macron-dead_macron
b breve-dead_breve
D abovedot-dead_abovedot
d diaeresis-dead_diaeresis
o degree-dead_abovering
A doubleacute-dead_doubleacute
r caron-dead_caron
e cedilla-dead_cedilla
- If you just want a subset use the first letter label, e.g.
" -remap DEAD=ga" to get the first two. Additional
remaps may also be supplied via commas, e.g. " -remap
DEAD=ga,Super_R-Button2". Finally, "DEAD=missing"
means to apply all of the above as long as the left hand member is not
already in the X11 keymap.
-norepeat, -repeat
- Option -norepeat disables X server key auto repeat
when VNC clients are connected and VNC keyboard input is not idle for more
than 5 minutes. This works around a repeating keystrokes bug (triggered by
long processing delays between key down and key up client events: either
from large screen changes or high latency). Default: -norepeat
- You can set the env. var. X11VNC_IDLE_TIMEOUT to the number
of idle seconds you want (5min = 300secs).
- Note: your VNC viewer side will likely do autorepeating, so
this is no loss unless someone is simultaneously at the real X
display.
- Use "-norepeat N" to set how many
times norepeat will be reset if something else (e.g. X session manager)
undoes it. The default is 2. Use a negative value for unlimited
resets.
-nofb
- Ignore video framebuffer: only process keyboard and
pointer. Intended for use with Win2VNC and x2vnc dual-monitor setups.
-nobell
- Do not watch for XBell events. (no beeps will be heard)
Note: XBell monitoring requires the XKEYBOARD extension.
-nosel
- Do not manage exchange of X selection/cutbuffer between VNC
viewers and the X server at all.
-noprimary
- Do not poll the PRIMARY selection for changes to send back
to clients. (PRIMARY is still set on received changes, however).
-nosetprimary
- Do not set the PRIMARY selection for changes received from
VNC clients.
-noclipboard
- Do not poll the CLIPBOARD selection for changes to send
back to clients. (CLIPBOARD is still set on received changes,
however).
-nosetclipboard
- Do not set the CLIPBOARD selection for changes received
from VNC clients.
-seldir string
- If direction string is "send", only send the
selection to viewers, and if it is "recv" only receive it from
viewers. To work around apps setting the selection too frequently and
messing up the other end. You can actually supply a comma separated list
of directions, including "debug" to turn on debugging
output.
-cursor [mode], -nocursor
- Sets how the pointer cursor shape (little icon at the mouse
pointer) should be handled. The "mode" string is optional and is
described below. The default is to show some sort of cursor shape(s). How
this is done depends on the VNC viewer and the X server. Use
-nocursor to disable cursor shapes completely.
- Some VNC viewers support the TightVNC CursorPosUpdates and
CursorShapeUpdates extensions (cuts down on network traffic by not having
to send the cursor image every time the pointer is moved), in which case
these extensions are used (see -nocursorshape and
-nocursorpos below to disable). For other viewers the cursor shape
is written directly to the framebuffer every time the pointer is moved or
changed and gets sent along with the other framebuffer updates. In this
case, there will be some lag between the vnc viewer pointer and the remote
cursor position.
- If the X display supports retrieving the cursor shape
information from the X server, then the default is to use that mode. On
Solaris this can be done with the SUN_OVL extension using -overlay
(see also the -overlay_nocursor option). A similar overlay scheme
is used on IRIX. Xorg (e.g. Linux) and recent Solaris Xsun servers support
the XFIXES extension to retrieve the exact cursor shape from the X server.
If XFIXES is present it is preferred over Overlay and is used by default
(see -noxfixes below). This can be disabled with -nocursor,
and also some values of the "mode" option below.
- Note that under XFIXES cursors with transparency (alpha
channel) will usually not be exactly represented and one may find Overlay
preferable. See also the -alphacut and -alphafrac options
below as fudge factors to try to improve the situation for cursors with
transparency for a given theme.
- The "mode" string can be used to fine-tune the
displaying of cursor shapes. It can be used the following ways:
- "-cursor arrow" - just show the
standard arrow nothing more or nothing less.
- "-cursor none" - same as
"-nocursor"
- "-cursor X" - when the cursor
appears to be on the root window, draw the familiar X shape. Some desktops
such as GNOME cover up the root window completely, and so this will not
work, try "X1", etc, to try to shift the tree depth. On high
latency links or slow machines there will be a time lag between expected
and the actual cursor shape.
- "-cursor some" - like "X"
but use additional heuristics to try to guess if the window should have a
windowmanager-like resizer cursor or a text input I-beam cursor. This is a
complete hack, but may be useful in some situations because it provides a
little more feedback about the cursor shape.
- "-cursor most" - try to show as
many cursors as possible. Often this will only be the same as
"some" unless the display has overlay visuals or XFIXES
extensions available. On Solaris and IRIX if XFIXES is not available,
-overlay mode will be attempted.
-cursor_drag
- Show cursor shape changes even when the mouse is being
dragged with a mouse button down. This is useful if you want to be able to
see Drag-and-Drop cursor icons, etc.
-arrow n
- Choose an alternate "arrow" cursor from a set of
some common ones. n can be 1 to 6. Default is: 1 Ignored when in XFIXES
cursor-grabbing mode.
-noxfixes
- Do not use the XFIXES extension to draw the exact cursor
shape even if it is available.
- Note: To work around a crash in Xorg 1.5 and later some
people needed to use -noxfixes. The Xorg crash occurred right after
a Display Manager (e.g. GDM) login. Starting with x11vnc 0.9.9 it tries to
automatically avoid using XFIXES until it is sure a window manager is
running. See the -reopen option for more info and how to use
X11VNC_AVOID_WINDOWS=never to disable it.
-alphacut n
- When using the XFIXES extension for the cursor shape,
cursors with transparency will not usually be displayed exactly (but
opaque ones will). This option sets n as a cutoff for cursors that have
transparency ("alpha channel" with values ranging from 0 to 255)
Any cursor pixel with alpha value less than n becomes completely
transparent. Otherwise the pixel is completely opaque. Default 240
-alphafrac fraction
- With the threshold in -alphacut some cursors will
become almost completely transparent because their alpha values are not
high enough. For those cursors adjust the alpha threshold until fraction
of the non-zero alpha channel pixels become opaque. Default 0.33
-alpharemove
- By default, XFIXES cursors pixels with transparency have
the alpha factor multiplied into the RGB color values (i.e. that
corresponding to blending the cursor with a black background). Specify
this option to remove the alpha factor. (useful for light colored
semi-transparent cursors).
-noalphablend
- In XFIXES mode do not send cursor alpha channel data to
LibVNCServer. The default is to send it. The alphablend effect will only
be visible in -nocursorshape mode or for clients with
cursorshapeupdates turned off. (However there is a hack for 32bpp with
depth 24, it uses the extra 8 bits to store cursor transparency for use
with a hacked vncviewer that applies the transparency locally. See the FAQ
for more info).
-nocursorshape
- Do not use the TightVNC CursorShapeUpdates extension even
if clients support it. See -cursor above.
-cursorpos, -nocursorpos
- Option -cursorpos enables sending the X cursor
position back to all vnc clients that support the TightVNC
CursorPosUpdates extension. Other clients will be able to see the pointer
motions. Default: -cursorpos
-xwarppointer, -noxwarppointer
- Move the pointer with XWarpPointer(3X) instead of
the XTEST extension. Use this as a workaround if the pointer motion
behaves incorrectly, e.g. on touchscreens or other non-standard
setups.
- It is also sometimes needed on XINERAMA displays and is
enabled by default if XINERAMA is found to be active. To prevent this, use
-noxwarppointer.
-always_inject
- Even if there is no displacement (dx = dy = 0) for a VNC
mouse event force the pointer to the indicated x,y position anyway. Recent
(2009) gui toolkits (gnome) have problems with x11vnc's original mouse
input injection method. So x11vnc's mouse input injection method has been
modified. To regain the OLD behavior use this option:
-always_inject. Then x11vnc will always force positioning the mouse
to the x,y position even if that position has not changed since the
previous VNC input event.
- The first place this problem was noticed was in gnome
terminal: if you pressed and released mouse button 3, a menu was posted
and then its first element 'New Terminal Window' was activated. This was
because x11vnc injected the mouse position twice: once on ButtonPress and
again on ButtonRelease. The toolkit interpreted the 2nd one as mouse
motion even though the mouse hadn't moved. So now by default x11vnc tries
to avoid injecting the 2nd one.
- Note that with the new default x11vnc will be oblivious to
applications moving the pointer (warping) or the user at the physical
display moving it. So it might, e.g., inject ButtonRelease at the wrong
position. If this (or similar scenarios) causes problems in your
environment, specify -always_inject for the old method.
-buttonmap string
- String to remap mouse buttons. Format: IJK-LMN, this maps
buttons I -> L, etc., e.g. -buttonmap 13-31
- Button presses can also be mapped to keystrokes: replace a
button digit on the right of the dash with :<sym>: or
:<sym1>+<sym2>: etc. for multiple keys. For example, if the
viewing machine has a mouse-wheel (buttons 4 5) but the x11vnc side does
not, these will do scrolls:
- -buttonmap 12345-123:Prior::Next:
- -buttonmap 12345-123:Up+Up+Up::Down+Down+Down:
- See <X11/keysymdef.h> header file for a list of
Keysyms, or use the xev(1) program. Note: mapping of button clicks
to Keysyms may not work if -modtweak or -xkb is needed for
the Keysym.
- If you include a modifier like "Shift_L" the
modifier's up/down state is toggled, e.g. to send "The" use
:Shift_L+t+Shift_L+h+e: (the 1st one is shift down and the 2nd one is
shift up). (note: the initial state of the modifier is ignored and not
reset) To include button events use "Button1", ... etc.
- -buttonmap currently does not work on MacOSX console
or in -rawfb mode.
- Workaround: use -buttonmap IJ...-LM...=n to limit
the number of mouse buttons to n, e.g. 123-123=3. This will prevent x11vnc
from crashing if the X server reports there are 5 buttons (4/5 scroll
wheel), but there are only really 3.
-nodragging
- Do not update the display during mouse dragging events
(mouse button held down). Greatly improves response on slow setups, but
you lose all visual feedback for drags, text selection, and some menu
traversals. It overrides any -pointer_mode setting.
-ncache n
- Client-side caching scheme. Framebuffer memory n (an
integer) times that of the full display is allocated below the actual
framebuffer to cache screen contents for rapid retrieval. So a W x H
frambuffer is expanded to a W x (n+1)*H one. Use 0 to disable.
- The n is actually optional, the default is 10.
- For this and the other -ncache* options below you
can abbreviate " -ncache" with "-nc".
Also, " -nonc" is the same as " -ncache
0"
- This is an experimental option, currently implemented in an
awkward way in that in the VNC Viewer you can see the pixel cache contents
if you scroll down, etc. So you will have to set things up so you can't
see that region. If this method is successful, the changes required for
clients to do this less awkwardly will be investigated.
- The SSVNC viewer does a good job at automatically hiding
the pixel cache region. Or use SSVNC's -ycrop option to explicitly
hide the region.
- Note that this mode consumes a huge amount of memory, both
on the x11vnc server side and on the VNC Viewer side. If n=2 then the
amount of RAM used is roughly tripled for both x11vnc and the VNC Viewer.
As a rule of thumb, note that 1280x1024 at depth 24 is about 5MB of pixel
data.
- For reasonable response when cycling through 4 to 6 large
(e.g. web browser) windows a value n of 6 to 12 is recommended. (that's
right: ~10X more memory...)
- Because of the way window backingstore and saveunders are
implemented, n must be even. It will be incremented by 1 if it is
not.
- This mode also works for native MacOS X, but may not be as
effective as the X version. This is due to a number of things, one is the
drop-shadow compositing that leaves extra areas that need to be repaired
(see -ncache_pad). Another is the window iconification animations
need to be avoided (see -macicontime). It appears the that the
'Scale' animation mode gives better results than the 'Genie' one. Also,
window event detection not as accurate as the X version.
-ncache_cr
- In -ncache mode, try to do copyrect opaque window
moves/drags instead of wireframes (this can induce painting errors). The
wireframe will still be used when moving a window whose save-unders has
not yet been set or has been invalidated.
- Some VNC Viewers provide better response than others with
this option. On Unix, realvnc viewer gives smoother drags than tightvnc
viewer. Response may also be choppy if the server side machine is too
slow.
- Sometimes on very slow modem connections, this actually
gives an improvement because no pixel data at all (not even the box
animation) is sent during the drag.
-ncache_no_moveraise
- In -ncache mode, do not assume that moving a window
will cause the window manager to raise it to the top of the stack. The
default is to assume it does, and so at the beginning of any wireframe,
etc, window moves the window will be pushed to top in the VNC viewer.
-ncache_no_dtchange
- In -ncache mode, do not try to guess when the
desktop (viewport) changes to another one (i.e. another workarea). The
default is to try to guess and when detected try to make the transistion
more smoothly.
-ncache_no_rootpixmap
- In -ncache mode, do not try to snapshot the desktop
background to use in guessing or reconstructing window save-unders.
-ncache_keep_anims
- In -ncache mode, do not try to disable window
manager animations and other effects (that usually degrade ncache
performance or cause painting errors). The default is to try to disable
them on KDE (but not GNOME) when VNC clients are connected.
- For other window managers or desktops that provide
animations, effects, compositing, translucency, etc. that interfere with
the -ncache method you will have to disable them manually.
-ncache_old_wm
- In -ncache mode, enable some heuristics for old
style window managers such as fvwm and twm.
-ncache_pad n
- In -ncache mode, pad each window with n pixels for
the caching rectangles. This can be used to try to improve the situation
with dropshadows or other compositing (e.g. MacOS X window manager),
although it could make things worse. The default is 0 on Unix and 24 on
MacOS X.
-debug_ncache
- Turn on debugging and profiling output under
-ncache.
-wireframe [str], -nowireframe
- Try to detect window moves or resizes when a mouse button
is held down and show a wireframe instead of the full opaque window. This
is based completely on heuristics and may not always work: it depends on
your window manager and even how you move things around. See
-pointer_mode below for discussion of the "bogging down"
problem this tries to avoid. Default: -wireframe
- Shorter aliases: -wf [str] and -nowf
- The value "str" is optional and, of course, is
packed with many tunable parameters for this scheme:
- Format: shade,linewidth,percent,T+B+L+R,mod,t1+t2+t3+t4
Default: 0xff,2,0,32+8+8+8,all,0.15+0.30+5.0+0.125
- If you leave nothing between commas: ",," the
default value is used. If you don't specify enough commas, the trailing
parameters are set to their defaults.
- "shade" indicate the "color" for the
wireframe, usually a greyscale: 0-255, however for 16 and 32bpp you can
specify an rgb.txt X color (e.g. "dodgerblue") or a value >
255 is treated as RGB (e.g. red is 0xff0000). "linewidth" sets
the width of the wireframe in pixels. "percent" indicates to not
apply the wireframe scheme to windows with area less than this percent of
the full screen.
- "T+B+L+R" indicates four integers for how close
in pixels the pointer has to be from the Top, Bottom, Left, or Right edges
of the window to consider wireframing. This is a speedup to quickly
exclude a window from being wireframed: set them all to zero to not try
the speedup (scrolling and selecting text will likely be slower).
- "mod" specifies if a button down event in the
interior of the window with a modifier key (Alt, Shift, etc.) down should
indicate a wireframe opportunity. It can be "0" or
"none" to skip it, "1" or "all" to apply it
to any modifier, or "Shift", "Alt",
"Control", "Meta", "Super", or
"Hyper" to only apply for that type of modifier key.
- "t1+t2+t3+t4" specify four floating point times
in seconds: t1 is how long to wait for the pointer to move, t2 is how long
to wait for the window to start moving or being resized (for some window
managers this can be rather long), t3 is how long to keep a wireframe
moving before repainting the window. t4 is the minimum time between
sending wireframe "animations". If a slow link is detected,
these values may be automatically changed to something better for a slow
link.
-nowireframelocal
- By default, mouse motion and button presses of a user
sitting at the LOCAL display are monitored for wireframing opportunities
(so that the changes will be sent efficiently to the VNC clients). Use
this option to disable this behavior.
-wirecopyrect mode, -nowirecopyrect
- Since the -wireframe mechanism evidently tracks
moving windows accurately, a speedup can be obtained by telling the VNC
viewers to locally copy the translated window region. This is the VNC
CopyRect encoding: the framebuffer update doesn't need to send the actual
new image data.
- Shorter aliases: -wcr [mode] and -nowcr
- "mode" can be "never" (same as
-nowirecopyrect) to never try the copyrect, "top" means
only do it if the window was not covered by any other windows, and
"always" means to translate the orginally unobscured region
(this may look odd as the remaining pieces come in, but helps on a slow
link). Default: "always"
- Note: there can be painting errors or slow response when
using -scale so you may want to disable CopyRect in this case
" -wirecopyrect never" on the command line or by
remote-control. Or you can also use the " -scale
xxx:nocr" scale option.
-debug_wireframe
- Turn on debugging info printout for the wireframe
heuristics. " -dwf" is an alias. Specify multiple times
for more output.
-scrollcopyrect mode, -noscrollcopyrect
- Like -wirecopyrect, but use heuristics to try to
guess if a window has scrolled its contents (either vertically or
horizontally). This requires the RECORD X extension to "snoop"
on X applications (currently for certain XCopyArea and XConfigureWindow X
protocol requests). Examples: Hitting <Return> in a terminal window
when the cursor was at the bottom, the text scrolls up one line. Hitting
<Down> arrow in a web browser window, the web page scrolls up a
small amount. Or scrolling with a scrollbar or mouse wheel.
- Shorter aliases: -scr [mode] and -noscr
- This scheme will not always detect scrolls, but when it
does there is a nice speedup from using the VNC CopyRect encoding (see
-wirecopyrect). The speedup is both in reduced network traffic and
reduced X framebuffer polling/copying. On the other hand, it may induce
undesired transients (e.g. a terminal cursor being scrolled up when it
should not be) or other painting errors (window tearing, bunching-up,
etc). These are automatically repaired in a short period of time. If this
is unacceptable disable the feature with -noscrollcopyrect.
- Screen clearing kludges: for testing at least, there are
some "magic key sequences" (must be done in less than 1 second)
to aid repairing painting errors that may be seen when using this
mode:
- 3 Alt_L's in a row: resend whole screen, 4 Alt_L's in a
row: reread and resend whole screen, 3 Super_L's in a row: mark whole
screen for polling, 4 Super_L's in a row: reset RECORD context, 5
Super_L's in a row: try to push a black screen
- note: Alt_L is the Left "Alt" key (a single key)
Super_L is the Left "Super" key (Windows flag). Both of these
are modifier keys, and so should not generate characters when pressed by
themselves. Also, your VNC viewer may have its own refresh hot-key or
button.
- "mode" can be "never" (same as
-noscrollcopyrect) to never try the copyrect, "keys"
means to try it in response to keystrokes only, "mouse" means to
try it in response to mouse events only, "always" means to do
both. Default: "always"
- Note: there can be painting errors or slow response when
using -scale so you may want to disable CopyRect in this case
" -scrollcopyrect never" on the command line or by
remote-control. Or you can also use the " -scale
xxx:nocr" scale option.
-scr_area n
- Set the minimum area in pixels for a rectangle to be
considered for the -scrollcopyrect detection scheme. This is to
avoid wasting the effort on small rectangles that would be quickly updated
the normal way. E.g. suppose an app updated the position of its skinny
scrollbar first and then shifted the large panel it controlled. We want to
be sure to skip the small scrollbar and get the large panel. Default:
60000
-scr_skip list
- Skip scroll detection for applications matching the comma
separated list of strings in list. Some applications implement
their scrolling in strange ways where the XCopyArea, etc, also applies to
invisible portions of the window: if we CopyRect those areas it looks
awful during the scroll and there may be painting errors left after the
scroll. Soffice.bin is the worst known offender.
- Use "##" to denote the start of the application
class (e.g. "##XTerm") and "++" to denote the start of
the application instance name (e.g. "++xterm"). The string your
list is matched against is of the form
"^^WM_NAME##Class++Instance<same-for-any-subwindows>" The
"xlsclients -la" command will provide this info.
- If a pattern is prefixed with "KEY:" it only
applies to Keystroke generated scrolls (e.g. Up arrow). If it is prefixed
with "MOUSE:" it only applies to Mouse induced scrolls (e.g.
dragging on a scrollbar). Default:
##Soffice.bin,##StarOffice,##OpenOffice
-scr_inc list
- Opposite of -scr_skip: this list is consulted first
and if there is a match the window will be monitored via RECORD for
scrolls irrespective of -scr_skip. Use -scr_skip '*' to skip
anything that does not match your -scr_inc. Use -scr_inc '*'
to include everything.
-scr_keys list
- For keystroke scroll detection, only apply the RECORD
heuristics to the comma separated list of keysyms in list. You may
find the RECORD overhead for every one of your keystrokes disrupts typing
too much, but you don't want to turn it off completely with "
-scr mouse" and -scr_parms does not work or is
too confusing.
- The listed keysyms can be numeric or the keysym names in
the <X11/keysymdef.h> header file or from the xev(1) program.
Example: " -scr_keys Up,Down,Return". One probably
wants to have application specific lists (e.g. for terminals, etc) but
that is too icky to think about for now...
- If list begins with the "-" character the
list is taken as an exclude list: all keysyms except those list will be
considered. The special string "builtin" expands to an internal
list of keysyms that are likely to cause scrolls. BTW, by default modifier
keys, Shift_L, Control_R, etc, are skipped since they almost never induce
scrolling by themselves.
-scr_term list
- Yet another cosmetic kludge. Apply shell/terminal
heuristics to applications matching comma separated list (same as for
-scr_skip/-scr_inc). For example an annoying transient under scroll
detection is if you hit Enter in a terminal shell with full text window,
the solid text cursor block will be scrolled up. So for a short time there
are two (or more) block cursors on the screen. There are similar
scenarios, (e.g. an output line is duplicated).
- These transients are induced by the approximation of scroll
detection (e.g. it detects the scroll, but not the fact that the block
cursor was cleared just before the scroll). In nearly all cases these
transient errors are repaired when the true X framebuffer is consulted by
the normal polling. But they are distracting, so what this option provides
is extra "padding" near the bottom of the terminal window: a few
extra lines near the bottom will not be scrolled, but rather updated from
the actual X framebuffer. This usually reduces the annoying artifacts. Use
"none" to disable. Default: "term"
-scr_keyrepeat lo-hi
- If a key is held down (or otherwise repeats rapidly) and
this induces a rapid sequence of scrolls (e.g. holding down an Arrow key)
the "scrollcopyrect" detection and overhead may not be able to
keep up. A time per single scroll estimate is performed and if that
estimate predicts a sustainable scrollrate of keys per second between
"lo" and "hi" then repeated keys will be DISCARDED to
maintain the scrollrate. For example your key autorepeat may be 25
keys/sec, but for a large window or slow link only 8 scrolls per second
can be sustained, then roughly 2 out of every 3 repeated keys will be
discarded during this period. Default: "4-20"
-scr_parms string
- Set various parameters for the scrollcopyrect mode. The
format is similar to that for -wireframe and packed with lots of
parameters:
- Format: T+B+L+R,t1+t2+t3,s1+s2+s3+s4+s5 Default:
0+64+32+32,0.02+0.10+0.9,0.03+0.06+0.5+0.1+5.0
- If you leave nothing between commas: ",," the
default value is used. If you don't specify enough commas, the trailing
parameters are set to their defaults.
- "T+B+L+R" indicates four integers for how close
in pixels the pointer has to be from the Top, Bottom, Left, or Right edges
of the window to consider scrollcopyrect. If -wireframe overlaps it
takes precedence. This is a speedup to quickly exclude a window from being
watched for scrollcopyrect: set them all to zero to not try the speedup
(things like selecting text will likely be slower).
- "t1+t2+t3" specify three floating point times in
seconds that apply to scrollcopyrect detection with *Keystroke* input: t1
is how long to wait after a key is pressed for the first scroll, t2 is how
long to keep looking after a Keystroke scroll for more scrolls. t3 is how
frequently to try to update surrounding scrollbars outside of the
scrolling area (0.0 to disable)
- "s1+s2+s3+s4+s5" specify five floating point
times in seconds that apply to scrollcopyrect detection with *Mouse*
input: s1 is how long to wait after a mouse button is pressed for the
first scroll, s2 is how long to keep waiting for additional scrolls after
the first Mouse scroll was detected. s3 is how frequently to try to update
surrounding scrollbars outside of the scrolling area (0.0 to disable). s4
is how long to buffer pointer motion (to try to get fewer, bigger mouse
scrolls). s5 is the maximum time to spend just updating the scroll window
without updating the rest of the screen.
-fixscreen string
- Periodically "repair" the screen based on
settings in string. Hopefully you won't need this option, it is
intended for cases when the -scrollcopyrect or -wirecopyrect
features leave too many painting errors, but it can be used for any
scenario. This option periodically performs costly operations and so
interactive response may be reduced when it is on. You can use 3 Alt_L's
(the Left "Alt" key) taps in a row (as described under
-scrollcopyrect) instead to manually request a screen repaint when
it is needed.
- string is a comma separated list of one or more of
the following: "V=t", "C=t", "X=t", and
"8=t". In these "t" stands for a time in seconds (it
is a floating point even though one should usually use values > 2 to
avoid wasting resources). V sets how frequently the entire screen should
be sent to viewers (it is like the 3 Alt_L's). C sets how long to wait
after a CopyRect to repaint the full screen. X sets how frequently to
reread the full X11 framebuffer from the X server and push it out to
connected viewers. Use of X should be rare, please report a bug if you
find you need it. 8= applies only for -8to24 mode: it sets how
often the non-default visual regions of the screen (e.g. 8bpp windows) are
refreshed. Examples: -fixscreen V=10 -fixscreen C=10
-debug_scroll
- Turn on debugging info printout for the scroll heuristics.
" -ds" is an alias. Specify it multiple times for more
output.
-noxrecord
- Disable any use of the RECORD extension. This is currently
used by the -scrollcopyrect scheme and to monitor X server
grabs.
-grab_buster, -nograb_buster
- Some of the use of the RECORD extension can leave a tiny
window for XGrabServer deadlock. This is only if the whole-server grabbing
application expects mouse or keyboard input before releasing the grab. It
is usually a window manager that does this. x11vnc takes care to avoid the
problem, but if caught x11vnc will freeze. Without -grab_buster,
the only solution is to go the physical display and give it some input to
satisfy the grabbing app. Or manually kill and restart the window manager
if that is feasible. With -grab_buster, x11vnc will fork a helper
thread and if x11vnc appears to be stuck in a grab after a period of time
(20-30 sec) then it will inject some user input: button clicks, Escape,
mouse motion, etc to try to break the grab. If you experience a lot of
grab deadlock, please report a bug.
-debug_grabs
- Turn on debugging info printout with respect to
XGrabServer() deadlock for -scrollcopyrect__mode_.
-debug_sel
- Turn on debugging info printout with respect to PRIMARY,
CLIPBOARD, and CUTBUFFER0 selections.
-pointer_mode n
- Various pointer motion update schemes.
"-pm" is an alias. The problem is pointer motion can
cause rapid changes on the screen: consider the rapid changes when you
drag a large window around opaquely. Neither x11vnc's screen polling and
vnc compression routines nor the bandwidth to the vncviewers can keep up
these rapid screen changes: everything will bog down when dragging or
scrolling. So a scheme has to be used to "eat" much of that
pointer input before re-polling the screen and sending out framebuffer
updates. The mode number n can be 0 to 4 and selects one of the
schemes desribed below.
- Note that the -wireframe and
-scrollcopyrect__mode_s complement -pointer_mode by
detecting (and improving) certain periods of "rapid screen
change".
- n=0: does the same as -nodragging. (all screen
polling is suspended if a mouse button is pressed.)
- n=1: was the original scheme used to about Jan 2004: it
basically just skips -input_skip keyboard or pointer events before
repolling the screen.
- n=2 is an improved scheme: by watching the current rate of
input events it tries to detect if it should try to "eat"
additional pointer events before continuing.
- n=3 is basically a dynamic -nodragging mode: it
detects when the mouse motion has paused and then refreshes the
display.
- n=4 attempts to measures network rates and latency, the
video card read rate, and how many tiles have been changed on the screen.
From this, it aggressively tries to push screen "frames" when it
decides it has enough resources to do so. NOT FINISHED.
- The default n is 2. Note that modes 2, 3, 4 will skip
-input_skip keyboard events (but it will not count pointer events).
Also note that these modes are not available in -threads mode which
has its own pointer event handling mechanism.
- To try out the different pointer modes to see which one
gives the best response for your usage, it is convenient to use the remote
control function, for example "x11vnc -R pm:4" or the
tcl/tk gui (Tuning -> pointer_mode -> n).
-input_skip n
- For the pointer handling when non-threaded: try to read n
user input events before scanning display. n < 0 means to act as though
there is always user input. Default: 10
-allinput
- Have x11vnc read and process all available client input
before proceeding.
-input_eagerly
- Similar to -allinput but use the handleEventsEagerly
mechanism built into LibVNCServer.
-speeds rd,bw,lat
- x11vnc tries to estimate some speed parameters that are
used to optimize scheduling (e.g. -pointer_mode 4,
-wireframe, -scrollcopyrect) and other things. Use the
-speeds option to set these manually. The triple rd,bw,lat
corresponds to video h/w read rate in MB/sec, network bandwidth to clients
in KB/sec, and network latency to clients in milliseconds, respectively.
If a value is left blank, e.g. "-speeds ,100,15", then the
internal scheme is used to estimate the empty value(s).
- Typical PC video cards have read rates of 5-10 MB/sec. If
the framebuffer is in main memory instead of video h/w (e.g. SunRay,
shadowfb, dummy driver, Xvfb), the read rate may be much faster.
"x11perf -getimage500" can be used to get a lower bound
(remember to factor in the bytes per pixel). It is up to you to estimate
the network bandwith and latency to clients. For the latency the
ping(1) command can be used.
- For convenience there are some aliases provided, e.g.
" -speeds modem". The aliases are:
"modem" for 6,4,200; "dsl" for 6,100,50; and
"lan" for 6,5000,1
-wmdt string
- For some features, e.g. -wireframe and
-scrollcopyrect, x11vnc has to work around issues for certain
window managers or desktops (currently kde and xfce). By default it tries
to guess which one, but it can guess incorrectly. Use this option to
indicate which wm/dt. string can be "gnome",
"kde", "cde", "xfce", or "root"
(classic X wm). Anything else is interpreted as "root".
-debug_pointer
- Print debugging output for every pointer event.
-debug_keyboard
- Print debugging output for every keyboard event.
Same as
-dp and
-dk, respectively. Use multiple times for more
output.
-defer time
- Time in ms to delay sending updates to connected clients
(deferUpdateTime) Default: 20
-wait time
- Time in ms to pause between screen polls. Used to cut down
on load. Default: 20
-extra_fbur n
- Perform extra FrameBufferUpdateRequests checks to try to be
in better sync with the client's requests. What this does is perform extra
polls of the client socket at critical times (before '-defer' and '-wait'
calls.) The default is n=1. Set to a larger number to insert more checks
or set to n=0 to disable. A downside of these extra calls is that more
mouse input may be processed than desired.
-wait_ui factor
- Factor by which to cut the -wait time if there has
been recent user input (pointer or keyboard). Improves response, but
increases the load whenever you are moving the mouse or typing. Default:
2.00
-setdefer n
- When the -wait_ui mechanism cuts down the wait time
ms, set the defer time to the same ms value. n=1 to enable, 0 to disable,
and -1 to set defer to 0 (no delay). Similarly, 2 and -2 indicate
'urgent_update' mode should be used to push the updates even sooner.
Default: 1
-nowait_bog
- Do not detect if the screen polling is "bogging
down" and sleep more. Some activities with no user input can slow
things down a lot: consider a large terminal window with a long build
running in it continuously streaming text output. By default x11vnc will
try to detect this (3 screen polls in a row each longer than 0.25 sec with
no user input), and sleep up to 1.5 secs to let things "catch
up". Use this option to disable that detection.
-slow_fb time
- Floating point time in seconds to delay all screen polling.
For special purpose usage where a low frame rate is acceptable and
desirable, but you want the user input processed at the normal rate so you
cannot use -wait.
-xrefresh time
- Floating point time in seconds to indicate how often to do
the equivalent of xrefresh(1) to force all windows (in the viewable
area if -id, -sid, or -clip is used) to repaint
themselves. Use this only if applications misbehave by not repainting
themselves properly. See also -noxdamage.
-nap, -nonap
- Monitor activity and if it is low take longer naps between
screen polls to really cut down load when idle. Default: take naps
-sb time
- Time in seconds after NO activity (e.g. screen blank) to
really throttle down the screen polls (i.e. sleep for about 1.5 secs). Use
0 to disable. Default: 60 Set the env. var. X11VNC_SB_FACTOR to scale
it.
-readtimeout n
- Set LibVNCServer rfbMaxClientWait to n seconds. On slow
links that take a long time to paint the first screen LibVNCServer may hit
the timeout and drop the connection. Default: 20 seconds.
-ping n
- Send a 1x1 framebuffer update to all clients every n
seconds (e.g. to try to keep a network connection alive)
-nofbpm, -fbpm
- If the system supports the FBPM (Frame Buffer Power
Management) extension (i.e. some Sun systems), then prevent the video h/w
from going into a reduced power state when VNC clients are connected.
- FBPM capable video h/w save energy when the workstation is
idle by going into low power states (similar to DPMS for monitors). This
interferes with x11vnc's polling of the framebuffer data.
- "-nofbpm" means prevent FBPM low power
states whenever VNC clients are connected, while " -fbpm"
means to not monitor the FBPM state at all. See the xset(1) manpage
for details. -nofbpm is basically the same as running "xset
fbpm force on" periodically. Default: -fbpm
-nodpms, -dpms
- If the system supports the DPMS (Display Power Management
Signaling) extension, then prevent the monitor from going into a reduced
power state when VNC clients are connected.
- DPMS reduced power monitor states are a good thing and you
normally want the power down to take place (usually x11vnc has no problem
exporting the display in this state). You probably only want to use "
-nodpms" to work around problems with Screen Savers kicking on
in DPMS low power states. There is known problem with kdesktop_lock on KDE
where the screen saver keeps kicking in every time user input stops for a
second or two. Specifying " -nodpms" works around
it.
- "-nodpms" means prevent DPMS low power
states whenever VNC clients are connected, while " -dpms"
means to not monitor the DPMS state at all. See the xset(1) manpage
for details. -nodpms is basically the same as running "xset
dpms force on" periodically. Default: -dpms
-forcedpms
- If the system supports the DPMS (Display Power Management
Signaling) extension, then try to keep the monitor in a powered off state.
This is to prevent nosey people at the physical display from viewing what
is on the screen. Be sure to lock the screen before disconnecting.
- This method is far from bullet proof, e.g. suppose someone
attaches a non-DPMS monitor, or loads the machine so that there is a gap
of time before x11vnc restores the powered off state? On many machines if
he floods it with keyboard and mouse input he can see flashes of what is
on the screen before the DPMS off state is reestablished. For this to work
securely there would need to be support in the X server to do this exactly
rather than approximately with DPMS.
-clientdpms
- As -forcedpms but only when VNC clients are
connected.
-noserverdpms
- The UltraVNC ServerInput extension is supported. This
allows the VNC viewer to click a button that will cause the server
(x11vnc) to try to disable keyboard and mouse input at the physical
display and put the monitor in dpms powered off state. Use this option to
skip powering off the monitor.
-noultraext
- Disable the following UltraVNC extensions: SingleWindow and
ServerInput. The others managed by LibVNCServer (textchat, 1/n scaling,
rfbEncodingUltra) are not.
-chatwindow
- Place a local UltraVNC chat window on the X11 display that
x11vnc is polling. That way the person on the VNC viewer-side can chat
with the person at the physical X11 console. (e.g. helpdesk w/o
telephone)
- For this to work the SSVNC package (version 1.0.21 or
later) MUST BE installed on the system where x11vnc runs and the 'ssvnc'
command must be available in $PATH. The ssvncviewer is used as a chat
window helper. See http://www.karlrunge.com/x11vnc/ssvnc.html
- This option implies '-rfbversion 3.6' so as to trick
UltraVNC viewers, otherwise they assume chat is not available. To specify
a different rfbversion, place it after the -chatwindow option on
the cmdline.
- See also the remote control 'chaton' and 'chatoff' actions.
These can also be set from the tkx11vnc GUI.
-noxdamage
- Do not use the X DAMAGE extension to detect framebuffer
changes even if it is available. Use -xdamage if your default is to
have it off.
- x11vnc's use of the DAMAGE extension: 1) significantly
reduces the load when the screen is not changing much, and 2) detects
changed areas (small ones by default) more quickly.
- Currently the DAMAGE extension is overly conservative and
often reports large areas (e.g. a whole terminal or browser window) as
damaged even though the actual changed region is much smaller (sometimes
just a few pixels). So heuristics were introduced to skip large areas and
use the damage rectangles only as "hints" for the traditional
scanline polling. The following tuning parameters are introduced to adjust
this behavior:
-xd_area A
- Set the largest DAMAGE rectangle area A (in pixels:
width * height) to trust as truly damaged: the rectangle will be copied
from the framebuffer (slow) no matter what. Set to zero to trust *all*
rectangles. Default: 20000
-xd_mem f
- Set how long DAMAGE rectangles should be
"remembered", f is a floating point number and is in
units of the scanline repeat cycle time (32 iterations). The default (1.0)
should give no painting problems. Increase it if there are problems or
decrease it to live on the edge (perhaps useful on a slow machine).
-sigpipe string
- Broken pipe (SIGPIPE) handling. string can be
"ignore" or "exit". For "ignore"
LibVNCServer will handle the abrupt loss of a client and continue, for
"exit" x11vnc will cleanup and exit at the 1st broken
connection.
- This option is not really needed since LibVNCServer is
doing the correct thing now for quite some time. However, for convenience
you can use it to ignore other signals, e.g. " -sigpipe
ignore:HUP,INT,TERM" in case that would be useful for some
sort of application. You can also put "exit:.." in the list to
have x11vnc cleanup on the listed signals. " -sig" is an
alias for this option if you don't like the 'pipe'. Example: -sig
ignore:INT,TERM,exit:USR1
-threads, -nothreads
- Whether or not to use the threaded LibVNCServer algorithm
[rfbRunEventLoop] if libpthread is available. In this mode new threads
(one for input and one for output) are created to handle each new client.
Default: -nothreads.
- Thread stability is much improved in version 0.9.8.
- Multiple clients in threaded mode should be stable for the
ZRLE encoding on all platforms. The Tight and Zlib encodings are currently
only stable on Linux for multiple clients. Compile with
-DTLS=__thread if your OS and compiler and linker support it.
- For resizes (randr, etc.) set this env. var. to the number
of milliseconds to sleep: X11VNC_THREADS_NEW_FB_SLEEP at various places in
the do_new_fb() action. This is to let various activities settle. Default
is about 500ms.
- Multiple clients in threaded mode could yield better
performance for 'class-room' broadcasting usage; also in -appshare
broadcast mode. See also the -reflect option.
-fs f
- If the fraction of changed tiles in a poll is greater than
f, the whole screen is updated. Default: 0.75
-gaps n
- Heuristic to fill in gaps in rows or cols of n or less
tiles. Used to improve text paging. Default: 4
-grow n
- Heuristic to grow islands of changed tiles n or wider by
checking the tile near the boundary. Default: 3
-fuzz n
- Tolerance in pixels to mark a tiles edges as changed.
Default: 2
-debug_tiles
- Print debugging output for tiles, fb updates, etc.
-snapfb
- Instead of polling the X display framebuffer (fb) for
changes, periodically copy all of X display fb into main memory and
examine that copy for changes. (This setting also applies for non-X
-rawfb modes). Under some circumstances this will improve
interactive response, or at least make things look smoother, but in others
(most!) it will make the response worse. If the video h/w fb is such that
reading small tiles is very slow this mode could help. To keep the
"framerate" up the screen size x bpp cannot be too large. Note
that this mode is very wasteful of memory I/O resources (it makes full
screen copies even if nothing changes). It may be of use in video
capture-like applications, webcams, or where window tearing is a
problem.
-rawfb string
- Instead of polling X, poll the memory object specified in
string.
- For file polling, to memory map mmap(2) a file use:
"map:/path/to/a/file@WxHxB", with framebuffer Width, Height, and
Bits per pixel. "mmap:..." is the same.
- If there is trouble with mmap, use "file:/..."
for slower lseek(2) based reading.
- Use "snap:..." to imply -snapfb mode and
the "file:" access (this is for unseekable devices that only
provide the fb all at once, e.g. a video camera provides the whole
frame).
- For shared memory segments string is of the form:
"shm:N@WxHxB" which specifies a shmid N and with WxHxB as above.
See shmat(1) and ipcs(1)
- If you do not supply a type "map" is assumed if
the file exists (see the next paragraphs for some exceptions to
this.)
- If string is "setup:cmd", then the command
"cmd" is run and the first line from it is read and used as
string. This allows initializing the device, determining WxHxB,
etc. These are often done as root so take care.
- If the string begins with "video", see the
VIDEO4LINUX discussion below where the device may be queried for (and
possibly set) the framebuffer parameters.
- If the string begins with "console",
"/dev/fb", "fb", or "vt", see the LINUX
CONSOLE discussion below where the framebuffer device is opened and
keystrokes (and possibly mouse events) are inserted into the console.
- If the string begins with "vnc", see the VNC HOST
discussion below where the framebuffer is taken as that of another remote
VNC server.
- Optional suffixes are ":R/G/B" and "+O"
to specify red, green, and blue masks (in hex) and an offset into the
memory object. If the masks are not provided x11vnc guesses them based on
the bpp (if the colors look wrong, you need to provide the masks.)
- Another optional suffix is the Bytes Per Line which in some
cases is not WxB/8. Specify it as WxHxB-BPL e.g. 800x600x16-2048. This
could be a normal width 1024 at 16bpp fb, but only width 800 shows
up.
- So the full format is: mode:file@WxHxB:R/G/B+O-BPL
- Examples:
- -rawfb shm:210337933@800x600x32:ff/ff00/ff0000
- -rawfb map:/dev/fb0@1024x768x32
- -rawfb map:/tmp/Xvfb_screen0@640x480x8+3232
- -rawfb file:/tmp/my.pnm@250x200x24+37
- -rawfb file:/dev/urandom@128x128x8 -rawfb
snap:/dev/video0@320x240x24 -24to32 -rawfb video0
-rawfb video -pipeinput VID -rawfb console
-rawfb vt2 -rawfb vnc:somehost:0
- (see ipcs(1) and fbset(1) for the first two
examples)
- In general all user input is discarded by default (see the
-pipeinput option for how to use a helper program to insert). Most
of the X11 (screen, keyboard, mouse) options do not make sense and many
will cause this mode to crash, so please think twice before setting or
changing them in a running x11vnc.
- If you DO NOT want x11vnc to close the X DISPLAY in rawfb
mode, prepend a "+" e.g. +file:/dev/fb0... Keeping the display
open enables the default remote-control channel, which could be useful.
Alternatively, if you specify -noviewonly, then the mouse and
keyboard input are STILL sent to the X display, this usage should be very
rare, i.e. doing something strange with /dev/fb0.
- If the device is not "seekable" (e.g. webcam) try
reading it all at once in full snaps via the "snap:" mode (note:
this is a resource hog). If you are using file: or map: AND the device
needs to be reopened for *every* snapfb snapshot, set the environment
variable: SNAPFB_RAWFB_RESET=1 as well.
- If you want x11vnc to dynamically transform a 24bpp rawfb
to 32bpp (note that this will be slower) also supply the -24to32
option. This would be useful for, say, a video camera that delivers the
pixel data as 24bpp packed RGB. This is the default under
"video" mode if the bpp is 24.
- Normally the bits per pixel, B, is 8, 16, or 32 (or rarely
24), however there is also some support for B < 8 (e.g. old graphics
displays 4 bpp or 1 bpp). In this case you certainly must supply the masks
as well: WxHxB:R/G/B. The pixels will be padded out to 8 bpp using depth 8
truecolor. The scheme currently does not work with snap fb (ask if
interested.) B=1 monochrome example: file:/dev/urandom@128x128x1:1/1/1
Some other like this are 128x128x2:3/3/3 128x128x4:7/7/7
- For B < 8 framebuffers you can also set the env. var
RAWFB_CGA=1 to try a CGA mapping for B=4 (e.g. linux vga16fb driver.) Note
with low bpp and/or resolution VGA and VGA16 modes on the Linux console
one's attempt to export them via x11vnc can often be thwarted due to
special color palettes, pixel packings, and even video painting buffering.
OTOH, often experimenting with the RGB masks can yield something
recognizable.
- VIDEO4LINUX: on Linux some attempt is made to handle video
devices (webcams or TV tuners) automatically. The idea is the WxHxB will
be extracted from the device itself. So if you do not supply
"@WxHxB... parameters x11vnc will try to determine them. It first
tries the v4l API if that support has been compiled in. Otherwise it will
run the v4l- info(1) external program if it is available.
- The simplest examples are "-rawfb
video" and "-rawfb video1" which imply the device
file /dev/video and /dev/video1, respectively. You can also supply the
/dev if you like, e.g. " -rawfb /dev/video0"
- Since the video capture device framebuffer usually changes
continuously (e.g. brightness fluctuations), you may want to use the
-wait, -slow_fb, or -defer options to lower the
"framerate" to cut down on network VNC traffic.
- A more sophisticated video device scheme allows
initializing the device's settings using:
- -rawfb video:<settings>
- The prefix could also be, as above, e.g.
"video1:" to specify the device file. The v4l API must be
available for this to work. Otherwise, you will need to try to initialize
the device with an external program, e.g. xawtv, spcaview, and hope they
persist when x11vnc re-opens the device.
- <settings> is a comma separated list of key=value
pairs. The device's brightness, color, contrast, and hue can be set to
percentages, e.g. br=80,co=50,cn=44,hu=60.
- The device filename can be set too if needed (if it does
not start with "video"), e.g. fn=/dev/qcam.
- The width, height and bpp of the framebuffer can be set
via, e.g., w=160,h=120,bpp=16.
- Related to the bpp above, the pixel format can be set via
the fmt=XXX, where XXX can be one of: GREY, HI240, RGB555, RGB565, RGB24,
and RGB32 (with bpp 8, 8, 16, 16, 24, and 32 respectively). See
http://www.linuxtv.org for more info (V4L api).
- For TV/rf tuner cards one can set the tuning mode via
tun=XXX where XXX can be one of PAL, NTSC, SECAM, or AUTO.
- One can switch the input channel by the inp=XXX setting,
where XXX is the name of the input channel (Television, Composite1,
S-Video, etc). Use the name that is in the information about the device
that is printed at startup.
- For input channels with tuners (e.g. Television) one can
change which station is selected by the sta=XXX setting. XXX is the
station number. Currently only the ntsc-cable-us (US cable) channels are
built into x11vnc. See the -freqtab option below to supply one from
xawtv. If XXX is greater than 500, then it is interpreted as a raw
frequency in KHz.
- Example:
- -rawfb
video:br=80,w=320,h=240,fmt=RGB32,tun=NTSC,sta=47
- one might need to add inp=Television too for the input
channel to be TV if the card doesn't come up by default in that one.
- Note that not all video capture devices will support all of
the above settings.
- See the -pipeinput VID option below for a way to
control the settings through the VNC Viewer via keystrokes. As a shortcut,
if the string begins "Video.." instead of "video.."
then -pipeinput VID is implied.
- As above, if you specify a "@WxHxB..." after the
<settings> string they are used verbatim: the device is not queried
for the current values. Otherwise the device will be queried.
- LINUX CONSOLE: The following describes some ways to view
and possibly interact with the Linux text/graphics console (i.e. not X11
XFree86/Xorg)
- Note: If the LibVNCServer LinuxVNC program is on your
system you may want to use that instead of the following method because it
will be faster and more accurate for the Linux text console and includes
mouse support. There is, however, the basic LinuxVNC functionality in
x11vnc if you replace "console" with "vt" in the
examples below.
- If the rawfb string begins with "console" the
framebuffer device /dev/fb0 is opened and /dev/tty0 is opened too. The
latter is used to inject keystrokes (not all are supported, but the basic
ones are). You will need to be root to inject keystrokes, but not
necessarily to open /dev/fb0. /dev/tty0 refers to the active VT, to
indicate one explicitly, use, e.g., "console2" for /dev/tty2,
etc. by indicating the specific VT number.
- For the Linux framebuffer device, /dev/fb0, (fb1, etc) to
be enabled the appropriate kernel drivers must be loaded. E.g. vesafb or
vga16fb and also by setting the boot parameter vga=0x301 (or 0x314, 0x317,
etc.) (The vga=... method is the preferred way; set your machines up that
way.) Otherwise there will be a ´No such device' error. You can also
load a Linux framebuffer driver specific to your make of video card for
more functionality. Once the machine is booted one can often 'modprobe'
the fb driver as root to obtain a framebuffer device.
- If you cannot get /dev/fb0 working on Linux, try using the
LinuxVNC emulation mode by " -rawfb vtN" where N =
1, ... 6 is the Linux Virtual Terminal (aka virtual console) you wish to
view, e.g. " -rawfb vt2". Unlike /dev/fb mode, it
need not be the active Virtual Terminal. Note that this mode can only show
text and not graphics. x11vnc polls the text in /dev/vcsaN
- Set the env. var. RAWFB_VCSA_BW=1 to disable colors in the
"vtN" mode (i.e. black and white only.) If you do not prefer the
default 16bpp set RAWFB_VCSA_BPP to 8 or 32. If you need to tweak the
rawfb parameters by using the 'console_guess' string printed at startup,
be sure to indicate the snap: method.
- uinput: If the Linux version appears to be 2.6 or later and
the "uinput" module appears to be present (modprobe uinput),
then the uinput method will be used instead of /dev/ttyN. uinput allows
insertion of BOTH keystrokes and mouse input and so it preferred when
accessing graphical (e.g. QT-embedded) linux console apps. It also
provides more accurate keystroke insertion. See -pipeinput UINPUT
below for more information on this mode; you will have to use
-pipeinput if you want to tweak any UINPUT parameters. You may also
want to also use the -nodragging and -cursor none options.
Use "console0", etc or -pipeinput CONSOLE to force the
/dev/ttyN method.
- Note you can change the Linux VT remotely using the
chvt(1) command to make the one you want be the active one (e.g.
'chvt 3'). Sometimes switching out and back corrects the framebuffer's
graphics state. For the " -rawfb vtN" mode there
is no need to switch the VT's.
- To skip input injecting entirely use "consolex"
or "vtx".
- The string "/dev/fb0" (1, etc.) can be used
instead of "console". This can be used to specify a different
framebuffer device, e.g. /dev/fb1. As a shortcut the "/dev/" can
be dropped. If the name is something nonstandard, use
"console:/dev/foofb"
- If you do not want x11vnc to guess the framebuffer's WxHxB
and masks automatically (sometimes the kernel gives incorrect
information), specify them with a @WxHxB (and optional :R/G/B masks) at
the end of the string.
- Examples: -rawfb console -rawfb /dev/fb0
(same) -rawfb console3 (force /dev/tty3) -rawfb consolex (no
keystrokes or mouse) -rawfb console:/dev/nonstd -rawfb
console -pipeinput UINPUT:accel=4.0 -rawfb vt3 (/dev/tty3
w/o /dev/fb0)
- VNC HOST: if the -rawfb string is of the form
"vnc:host:N" then the VNC display "N" on the remote
VNC server "host" is connected to (i.e. x11vnc acts as a VNC
client itself) and that framebuffer is exported. This is the same as the
option " -reflect host:N".
- This mode is really only of use if you are trying to
improve performance in the case of many (e.g. >10) simultaneous VNC
viewers, and you try a divide and conquer scheme to reduce bandwidth and
improve responsiveness. However, another user found this mode useful to
export a demo display through a slow link: then multiple demo viewers
connected to the reflecting x11vnc on the fast side of the link, and so
avoided all of the demo viewers going through the slow link. Other users
have found this mode useful to be able to take advantage of some of
x11vnc's many features that other VNC servers do not have, for example SSL
encryption, single port http and https, unix usernames and passwords, and
-allow, -zeroconf, -clip, and -scale options
and others.
- For the classroom broadcast example, if there will be 64
simultaneous VNC viewers this can lead to a lot of redundant VNC traffic
to and from the server host:N, extra CPU usage, and all viewers response
can be reduced by having to wait for writes to the slowest client to
finish. However, if you set up 8 reflectors/repeaters started with option
-rawfb vnc:host:N, then there are only 8 connections to host:N.
Each repeater then handles 8 vnc viewer connections thereby spreading the
load around. In classroom broadcast usage, try to put the repeaters on
different switches. This mode is the same as -reflect host:N.
Replace "host:N" by "listen" or
"listen:port" for a reverse connection. Use
"listennofork:port" to use the LibVNCServer non forking client
listen interface (if your LibVNCServer has it), same as setting
X11VNC_REFLECT_NO_FORK=1.
- Overall performance will not be as good as a single direct
connection because, among other things, there is an additional level of
framebuffer polling and pointer motion can still induce many changes per
second that must be propagated. Tip: if the remote VNC is x11vnc doing
wireframing, or an X display that does wireframing that gives much better
response than opaque window dragging. Consider the -nodragging
option if the problem is severe.
- The env. var. X11VNC_REFLECT_PASSWORD can be set to the
password needed to log into the vnc host server, or to
"file:path_to_file" to indicate a file containing the password
as its first line.
- To set the pixel format that x11vnc requests as a VNC
CLIENT set the env. vars: X11VNC_REFLECT_bitsPerSample
X11VNC_REFLECT_samplesPerPixel, and X11VNC_REFLECT_bytesPerPixel; the
defaults are 8, 3, 4. 2, 3, 1 would give a low color mode. See the
function rfbGetClient() in libvncclient for more info.
- The VNC HOST mode implies -shared. Use
-noshared as a subsequent cmdline option to disable sharing.
-freqtab file
- For use with "-rawfb video" for TV
tuner devices to specify station frequencies. Instead of using the built
in ntsc-cable-us mapping of station number to frequency, use the data in
file. For stations that are not numeric, e.g. SE20, they are placed above
the highest numbered station in the order they are found. Example: "
-freqtab /usr/X11R6/share/xawtv/europe-west.list" You
can make your own freqtab by copying the xawtv format.
-pipeinput cmd
- This option lets you supply an external command in
cmd that x11vnc will pipe all of the user input events to in a
simple format. In -pipeinput mode by default x11vnc will not
process any of the user input events. If you prefix cmd with
"tee:" it will both send them to the pipe command and process
them. For a description of the format run "-pipeinput
tee:/bin/cat". Another prefix is "reopen" which means to
reopen pipe if it exits. Separate multiple prefixes with commas.
- In combination with -rawfb one might be able to do
amusing things (e.g. control non-X devices). To facilitate this, if
-rawfb is in effect then the value is stored in X11VNC_RAWFB_STR
for the pipe command to use if it wants. Do 'env | grep X11VNC' for
more.
- Built-in pipeinput modes (no external program
required):
- If cmd is "VID" and you are using the
-rawfb for a video capture device, then an internal list of
keyboard mappings is used to set parameters of the video. The mappings
are:
- "B" and "b" adjust the brightness up
and down. "H" and "h" adjust the hue. "C"
and "c" adjust the colour. "N" and "n"
adjust the contrast. "S" and "s" adjust the size of
the capture screen. "I" and "i" cycle through input
channels. Up and Down arrows adjust the station (if a tuner) F1, F2, ...,
F6 will switch the video capture pixel format to HI240, RGB565, RGB24,
RGB32, RGB555, and GREY respectively. See -rawfb video for
details.
- If cmd is "CONSOLE" or "CONSOLEn" where
n is a Linux console number, then the linux console keystroke insertion to
/dev/ttyN (see -rawfb console) is performed.
- If cmd begins with "UINPUT" then the Linux uinput
module is used to insert both keystroke and mouse events to the Linux
console (see -rawfb above). This usually is the /dev/input/uinput
device file (you may need to create it with "mknod /dev/input/uinput
c 10 223" and insert the module with "modprobe
uinput".
- The UINPUT mode currently only does US keyboards (a scan
code option may be added), and not all keysyms are supported. But it is
probably more accurate than the "CONSOLE" method.
- You may want to use the options -cursor none and
-nodragging in this mode.
- Additional tuning options may be supplied via:
UINPUT:opt1,opt2,... (a comma separated list). If an option begins with
"/" it is taken as the uinput device file.
- Which uinput is injected can be controlled by an option
string made of the characters "K", "M", and
"B" (see the -input option), e.g. "KM" allows
keystroke and motion but not button clicks.
- A UINPUT option of the form: accel=f, or accel=fx+fy sets
the mouse motion "acceleration". This is used to correct raw
mouse relative motion into how much the application cursor moves (x11vnc
has no control over, or knowledge of how the windowing application
interprets the raw mouse motions). Typically the acceleration for an X
display is 2 (see xset "m" option). "f" is a floating
point number, e.g. 3.0. Use "fx+fy" if you need to supply
different corrections for x and y.
- Note: the default acceleration is 2.0 since it seems both X
and qt-embedded often (but not always) use this value.
- Even with a correct accel setting the mouse position will
get out of sync (probably due to a mouse "threshold" setting
where the acceleration doe not apply, set xset(1) ). The option
reset=N sets the number of ms (default 150) after which the cursor is
attempted to be reset (by forcing the mouse to (0, 0) via small increments
and then back out to (x, y) in 1 jump), This correction seems to be needed
but can cause jerkiness or unexpected behavior with menus, etc. Use
reset=0 to disable.
- If you set the env. var X11VNC_UINPUT_THRESHOLDS then the
thresh=n mode will be enabled. It is currently not working well. If |dx|
<= thresh and |dy| < thresh no acceleration is applied. Use
"thresh=+n" |dx| + |dy| < thresh to be used instead
(X11?)
- Example: -pipeinput UINPUT:accel=4.0 -cursor
none
- If the uinput device has an absolute pointer (as opposed to
a normal mouse that is a relative pointer) you can specify the option
"abs". Note that a touchpad on a laptop is an absolute device to
some degree. This (usually) avoids all the problems with mouse
acceleration. If x11vnc has trouble deducing the size of the device, use
"abs=WxH". Furthermore, if the device is a touchscreen (assumed
to have an absolute pointer) use "touch" or
"touch=WxH". For touchscreens, when a mouse button is pressed, a
pressure increase is injected, and when the button is released a pressure
of zero is injected.
- If touch has been set, use "touch_always=1" to
indicate whenever the mouse moves with no button pressed, a touch event of
zero pressure should be sent anyway. Also use "btn_touch=1" to
indicate a BTN_TOUCH keystroke press or release should be sent instead of
a pressure change. Set "dragskip=n" to skip n dragged mouse
touches (with pressure applied) before injecting one. To indicate the
pressure that should be sent when there is a button click for a
touchscreen device, specify pressure=n, e.g. n=5. The default is n=1.
- If a touch screen is being used ("touch" above)
and it is having its input processed by tslib, you can specify the tslib
calibration file via tslib_cal=<file>. For example,
tslib_cal=/etc/pointercal. To get accurate or even usable positioning this
is required when tslib is in use.
- The Linux uinput mechanism can be bypassed and one can
write input events DIRECTLY to the devices instead. To do this, specify
one or more of the following for the input classes:
direct_rel=<device> direct_abs=<device>
direct_btn=<device> or direct_key=<device>. The <device>
file is usually something like /dev/input/event1 but you can specify any
device file or pipe. You must specify each one of the above classes even
if they correspond to the same device file (rel/abs and btn are often the
same.) Look at the file /proc/bus/input/devices to get an idea what is
available and the device filenames. Note: The /dev/input/mouse* devices do
not seem to work, use the corresponding /dev/input/event* file instead.
Any input class not directly specified as above will be handled via the
uinput mechanism. To disable creating a uinput device (and thereby
discarding unhandled input), specify "nouinput".
- Examples:
- -pipeinput UINPUT:direct_abs=/dev/input/event1
- this was used on a qtmoko Neo freerunner (armel):
- -pipeinput UINPUT:touch,tslib_cal=/etc/pointercal,
direct_abs=/dev/input/event1,nouinput,dragskip=4
- (where the long line has been split into two.)
- You can set the env. var X11VNC_UINPUT_DEBUG=1 or higher to
get debugging output for UINPUT mode.
-macnodim
- For the native MacOSX server, disable dimming.
-macnosleep
- For the native MacOSX server, disable display sleep.
-macnosaver
- For the native MacOSX server, disable screensaver.
-macnowait
- For the native MacOSX server, do not wait for the user to
switch back to his display.
-macwheel n
- For the native MacOSX server, set the mouse wheel speed to
n (default 5).
-macnoswap
- For the native MacOSX server, do not swap mouse buttons 2
and 3.
-macnoresize
- For the native MacOSX server, do not resize or reset the
framebuffer even if it is detected that the screen resolution or depth has
changed.
-maciconanim n
- For the native MacOSX server, set n to the number of
milliseconds that the window iconify/deiconify animation takes. In
-ncache mode this value will be used to skip the animation if
possible. (default 400)
-macmenu
- For the native MacOSX server, in -ncache client-side
caching mode, try to cache pull down menus (not perfect because they have
animated fades, etc.)
-macuskbd
- For the native MacOSX server, use the original keystroke
insertion code based on a US keyboard.
-macnoopengl
- For the native MacOSX server, do not use OpenGL for screen
capture, but rather use the original, deprecated raw memory access method:
addr = CGDisplayBaseAddress().
-macnorawfb
- For the native MacOSX server, disable the raw memory
address screen capture method.
- MACOSX NOTE: There are some deprecated MacOSX interfaces to
inject keyboard and mouse events and the raw memory access method is
deprecated as well (however, OpenGL will be preferred if available because
it is faster.) One can force not using any deprecated interfaces at
compile time by setting -DX11VNC_MACOSX_NO_DEPRECATED=1 in
CPPFLAGS. Or to turn them off one by one:
-DX11VNC_MACOSX_NO_DEPRECATED_LOCALEVENTS=1,
-DX11VNC_MACOSX_NO_DEPRECATED_POSTEVENTS=1 or
-DX11VNC_MACOSX_NO_DEPRECATED_FRAMEBUFFER=1 At run time, for
testing and workarounds, one can disable them by using: -env
X11VNC_MACOSX_NO_DEPRECATED=1 -env
X11VNC_MACOSX_NO_DEPRECATED_LOCALEVENTS=1 -env
X11VNC_MACOSX_NO_DEPRECATED_POSTEVENTS=1 or -env
X11VNC_MACOSX_NO_DEPRECATED_FRAMEBUFFER=1 Note: When doing either of these
for the mouse input not everything works currently, e.g. double clicks and
wireframing. Also, screen resolution and pixel depth changes will not be
automatically detected unless the deprecated framebuffer interfaces are
allowed.
- Conversely, if you are compiling on an older machine that
does not have some of the newer interfaces, you may need to specify
-DX11VNC_MACOSX_NO_CGEVENTCREATESCROLLWHEELEVENT
-DX11VNC_MACOSX_NO_CGEVENTCREATEMOUSEEVENT or
-DX11VNC_MACOSX_NO_CGEVENTCREATEKEYBOARDEVENT. Use
-DX11VNC_MACOSX_USE_GETMAINDEVICE to regain the very old QuickDraw
GetMainDevice() interface (rare...)
-gui [gui-opts]
- Start up a simple tcl/tk gui based on the remote control
options -remote/-query described below. Requires the
"wish" program to be installed on the machine.
"gui-opts" is not required: the default is to start up both the
full gui and x11vnc with the gui showing up on the X display in the
environment variable DISPLAY.
- "gui-opts" can be a comma separated list of
items. Currently there are these types of items: 1) a gui mode, a 2) gui
"simplicity", 3) the X display the gui should display on, 4) a
"tray" or "icon" mode, and 5) a gui geometry.
- 1) The gui mode can be "start", "conn",
or "wait" "start" is the default mode above and is not
required. "conn" means do not automatically start up x11vnc, but
instead just try to connect to an existing x11vnc process.
"wait" means just start the gui and nothing else (you will later
instruct the gui to start x11vnc or connect to an existing one.)
- 2) The gui simplicity is off by default (a power-user gui
with all options is presented) To start with something less daunting
supply the string "simple" ("ez" is an alias for
this). Once the gui is started you can toggle between the two with
"Misc -> simple_gui".
- 3) Note the possible confusion regarding the potentially
two different X displays: x11vnc polls one, but you may want the gui to
appear on another. For example, if you ssh in and x11vnc is not running
yet you may want the gui to come back to you via your ssh redirected X
display (e.g. localhost:10).
- If you do not specify a gui X display in
"gui-opts" then the DISPLAY environment variable and
-display option are tried (in that order). Regarding the x11vnc X
display the gui will try to communication with, it first tries
-display and then DISPLAY. For example, "x11vnc
-display :0 -gui otherhost:0", will remote control an
x11vnc polling :0 and display the gui on otherhost:0 The
"tray/icon" mode below reverses this preference, preferring to
display on the x11vnc display.
- 4) When "tray" or "icon" is specified,
the gui presents itself as a small icon with behavior typical of a
"system tray" or "dock applet". The color of the icon
indicates status (connected clients) and there is also a balloon status.
Clicking on the icon gives a menu from which properties, etc, can be set
and the full gui is available under "Advanced". To be fully
functional, the gui mode should be "start" (the default).
- Note that tray or icon mode will imply the -forever
x11vnc option (if the x11vnc server is started along with the gui) unless
-connect or -connect_or_exit has been specified. So x11vnc
(and the tray/icon gui) will wait for more connections after the first
client disconnects. If you want only one viewer connection include the
-once option.
- For "icon" the gui just a small standalone
window. For "tray" it will attempt to embed itself in the
"system tray" if possible. If "=setpass" is appended
then at startup the X11 user will be prompted to set the VNC session
password. If =<hexnumber> is appended that icon will attempt to
embed itself in the window given by hexnumber. Use =noadvanced to disable
the full gui. (To supply more than one, use "+" sign). E.g.
-gui tray=setpass and -gui icon=0x3600028
- Other modes: "full", the default and need not be
specified. " -gui none", do not show a gui, useful
to override a ~/.x11vncrc setting, etc.
- 5) When "geom=+X+Y" is specified, that geometry
is passed to the gui toplevel. This is the icon in icon/tray mode, or the
full gui otherwise. You can also specify width and height, i.e. WxH+X+Y,
but it is not recommended. In "tray" mode the geometry is
ignored unless the system tray manager does not seem to be running. One
could imagine using something like " -gui
tray,geom=+4000+4000" with a display manager to keep the gui
invisible until someone logs in...
- More icon tricks, "icon=minimal" gives an icon
just with the VNC display number. You can also set the font with
"iconfont=...". The following could be useful: "
-gui icon=minimal,iconfont=5x8,geom=24x10+0-0"
- General examples of the -gui option: "x11vnc
-gui", "x11vnc -gui ez" "x11vnc
-gui localhost:10", "x11vnc -gui
conn,host:0", "x11vnc -gui tray,ez" "x11vnc
-gui tray=setpass"
- If you do not intend to start x11vnc from the gui (i.e.
just remote control an existing one), then the gui process can run on a
different machine from the x11vnc server as long as X permissions, etc.
permit communication between the two.
- FONTS: On some systems the tk fonts can be too small,
jagged, or otherwise unreadable. There are 4 env vars you can set to be
the tk font you prefer:
- X11VNC_FONT_BOLD main font for menus and buttons.
X11VNC_FONT_FIXED font for fixed width text.
- X11VNC_FONT_BOLD_SMALL tray icon font.
X11VNC_FONT_REG_SMALL tray icon menu font.
- The last two only apply for the tray icon mode.
- Here are some examples:
- -env X11VNC_FONT_BOLD='Helvetica -16 bold'
-env X11VNC_FONT_FIXED='Courier -14' -env
X11VNC_FONT_REG_SMALL='Helvetica -12'
- You can put the lines like the above (without the quotes)
in your ~/.x11vncrc file to avoid having to specify them on the x11vnc
command line.
-remote command
- Remotely control some aspects of an already running x11vnc
server. " -R" and "-r" are aliases for
" -remote". After the remote control command is sent to
the running server the 'x11vnc -remote ...' x11vnc command exits.
You can often use the -query command (see below) to see if the
x11vnc server processed your -remote command.
- The default communication channel is that of X properties
(specifically X11VNC_REMOTE), and so this command must be run with correct
settings for DISPLAY and possibly XAUTHORITY to connect to the X server
and set the property. Alternatively, use the -display and
-auth options to set them to the correct values. The running server
cannot use the -novncconnect option because that disables the
communication channel. See below for alternate channels.
- For example: 'x11vnc -remote stop' (which is the
same as ´x11vnc -R stop') will close down the x11vnc server.
´x11vnc -R shared' will enable shared connections, and
´x11vnc -R scale:3/4' will rescale the desktop.
- To use a different name for the X11 property (e.g. to have
separate communication channels for multiple x11vnc's on the same display)
set the X11VNC_REMOTE environment variable to the string you want, for
example: -env X11VNC_REMOTE=X11VNC_REMOTE_12345 Both sides of the
channel must use the same unique name.
- To run a bunch of commands in a sequence use something
like: x11vnc -R 'script:firstcmd;secondcmd;...'
- Use x11vnc -R script:file=/path/to/file to read
commands from a file (can be multi-line and use the comment '#' character
in the normal way. The ';' separator must still be used to separate each
command.)
- To not try to contact another x11vnc process and instead
just run the command (or query) directly, prefix the command with the
string "DIRECT:"
- The following -remote/-R commands are
supported:
- stop terminate the server, same as "quit"
"exit" or "shutdown".
- ping see if the x11vnc server responds. return is:
ans=ping:<display>
- ping:mystring as above, but use your own unique string.
return is: ans=ping:mystring:<xdisplay>
- blacken try to push a black fb update to all clients (due
to timings a client could miss it). Same as "zero", also
"zero:x1,y1,x2,y2" for a rectangle.
- refresh send the entire fb to all clients.
- reset recreate the fb, polling memory, etc.
- id:windowid set -id window to "windowid".
empty or "root" to go back to root window
- sid:windowid set -sid window to
"windowid"
- id_cmd:cmd cmds: raise, lower, map, unmap, iconify,
move:dXdY, resize:dWdH, geom:WxH+X+Y. dX dY, dW, and dH must have a
leading "+" or "-" e.g.: move:-30+10 resize:+20+35
also: wm_delete, wm_name:string and icon_name:string. Also
id_cmd:win=N:cmd
- waitmapped wait until subwin is mapped.
- nowaitmapped do not wait until subwin is mapped.
- clip:WxH+X+Y set -clip mode to
"WxH+X+Y"
- flashcmap enable -flashcmap mode.
- noflashcmap disable -flashcmap mode.
- shiftcmap:n set -shiftcmap to n.
- notruecolor enable -notruecolor mode.
- truecolor disable -notruecolor mode.
- overlay enable -overlay mode (if applicable).
- nooverlay disable -overlay mode.
- overlay_cursor in -overlay mode, enable cursor
drawing.
- overlay_nocursor disable cursor drawing. same as
nooverlay_cursor.
- 8to24 enable -8to24 mode (if applicable).
- no8to24 disable -8to24 mode.
- 8to24_opts:str set the -8to24 opts to
"str".
- 24to32 enable -24to32 mode (if applicable).
- no24to32 disable -24to32 mode.
- visual:vis set -visual to "vis"
- scale:frac set -scale to "frac"
- scale_cursor:f set -scale_cursor to
"f"
- viewonly enable -viewonly mode.
- noviewonly disable -viewonly mode.
- shared enable -shared mode.
- noshared disable -shared mode.
- forever enable -forever mode.
- noforever disable -forever mode.
- timeout:n reset -timeout to n, if there are
currently no clients, exit unless one connects in the next n secs.
- tightfilexfer enable filetransfer for NEW clients.
- notightfilexfer disable filetransfer for NEW clients.
- ultrafilexfer enable filetransfer for clients.
- noultrafilexfer disable filetransfer for clients.
- rfbversion:n.m set -rfbversion for new clients.
- http enable http client connections.
- nohttp disable http client connections.
- deny deny any new connections, same as
"lock"
- nodeny allow new connections, same as
"unlock"
- avahi enable avahi service advertising.
- noavahi disable avahi service advertising.
- mdns enable avahi service advertising.
- nomdns disable avahi service advertising.
- zeroconf enable avahi service advertising.
- nozeroconf disable avahi service advertising.
- connect:host do reverse connection to host,
"host" may be a comma separated list of hosts or host:ports. See
-connect. Passwords required as with fwd connections. See
X11VNC_REVERSE_CONNECTION_NO_AUTH=1
- disconnect:host disconnect any clients from
"host" same as "close:host". Use host "all"
to close all current clients. If you know the client internal hex ID, e.g.
0x3 (returned by " -query clients" and
RFB_CLIENT_ID) you can use that too.
- proxy:host:port set reverse connection proxy (empty to
disable).
- allowonce:host For the next connection only, allow
connection from "host". In -ssl mode two connections are
allowed (i.e. Fetch Cert) unless X11VNC_NO_SSL_ALLOW_TWICE=1
- allow:hostlist set -allow list to (comma separated)
"hostlist". See -allow and -localhost. Do not use
with -allow /path/to/file Use "+host" to add a single
host, and use " -host" to delete a single host
- localhost enable -localhost mode
- nolocalhost disable -localhost mode
- listen:str set -listen to str, empty to
disable.
- noipv6 enable -noipv6 mode.
- ipv6 disable -noipv6 mode.
- noipv4 enable -noipv4 mode.
- ipv4 disable -noipv4 mode.
- 6 enable -6 IPv6 listening mode.
- no6 disable -6 IPv6 listening mode.
- lookup disable -nolookup mode.
- nolookup enable -nolookup mode.
- lookup disable -nolookup mode.
- input:str set -input to "str", empty to
disable.
- grabkbd enable -grabkbd mode.
- nograbkbd disable -grabkbd mode.
- grabptr enable -grabptr mode.
- nograbptr disable -grabptr mode.
- grabalways enable -grabalways mode.
- nograbalways disable -grabalways mode.
- grablocal:n set -grablocal to n.
- client_input:str set the K, M, B -input on a
per-client basis. select which client as for disconnect, e.g.
client_input:host:MB or client_input:0x2:K
- accept:cmd set -accept "cmd" (empty to
disable).
- afteraccept:cmd set -afteraccept (empty to
disable).
- gone:cmd set -gone "cmd" (empty to
disable).
- noshm enable -noshm mode.
- shm disable -noshm mode (i.e. use shm).
- flipbyteorder enable -flipbyteorder mode, you may
need to set noshm for this to do something.
- noflipbyteorder disable -flipbyteorder mode.
- onetile enable -onetile mode. (you may need to set
shm for this to do something)
- noonetile disable -onetile mode.
- solid enable -solid mode
- nosolid disable -solid mode.
- solid_color:color set -solid color (and apply
it).
- blackout:str set -blackout "str" (empty to
disable). See -blackout for the form of "str" (basically:
WxH+X+Y,...) Use "+WxH+X+Y" to append a single rectangle use
"-WxH+X+Y" to delete one
- xinerama enable -xinerama mode. (if applicable)
- noxinerama disable -xinerama mode.
- xtrap enable -xtrap input mode(if applicable)
- noxtrap disable -xtrap input mode.
- xrandr enable -xrandr mode. (if applicable)
- noxrandr disable -xrandr mode.
- xrandr_mode:mode set the -xrandr mode to
"mode".
- rotate:mode set the -rotate mode to
"mode".
- padgeom:WxH set -padgeom to WxH (empty to disable)
If WxH is "force" or "do" the padded geometry fb is
immediately applied.
- quiet enable -quiet mode.
- noquiet disable -quiet mode.
- modtweak enable -modtweak mode.
- nomodtweak enable -nomodtweak mode.
- xkb enable -xkb modtweak mode.
- noxkb disable -xkb modtweak mode.
- capslock enable -capslock mode.
- nocapslock disable -capslock mode.
- skip_lockkeys enable -skip_lockkeys mode.
- noskip_lockkeys disable -skip_lockkeys mode.
- skip_keycodes:str enable -xkb -skip_keycodes
"str".
- sloppy_keys enable -sloppy_keys mode.
- nosloppy_keys disable -sloppy_keys mode.
- skip_dups enable -skip_dups mode.
- noskip_dups disable -skip_dups mode.
- add_keysyms enable -add_keysyms mode.
- noadd_keysyms stop adding keysyms. those added will still
be removed at exit.
- clear_mods enable -clear_mods mode and clear
them.
- noclear_mods disable -clear_mods mode.
- clear_keys enable -clear_keys mode and clear
them.
- noclear_keys disable -clear_keys mode.
- clear_locks do the clear_locks action.
- clear_all do the clear_all action.
- keystate have x11vnc print current keystate.
- remap:str set -remap "str" (empty to
disable). See -remap for the form of "str" (basically:
key1-key2,key3-key4,...) Use "+key1-key2" to append a single
keymapping, use "-key1-key2" to delete.
- norepeat enable -norepeat mode.
- repeat disable -norepeat mode.
- nofb enable -nofb mode.
- fb disable -nofb mode.
- bell enable bell (if supported).
- nobell disable bell.
- sendbell ring the bell now.
- nosel enable -nosel mode.
- sel disable -nosel mode.
- noprimary enable -noprimary mode.
- primary disable -noprimary mode.
- nosetprimary enable -nosetprimary mode.
- setprimary disable -nosetprimary mode.
- noclipboard enable -noclipboard mode.
- clipboard disable -noclipboard mode.
- nosetclipboard enable -nosetclipboard mode.
- setclipboard disable -nosetclipboard mode.
- seldir:str set -seldir to "str"
- resend_cutbuffer resend the most recent CUTBUFFER0
copy
- resend_clipboard resend the most recent CLIPBOARD copy
- resend_primary resend the most recent PRIMARY copy
- cursor:mode enable -cursor "mode".
- show_cursor enable showing a cursor.
- noshow_cursor disable showing a cursor. (same as
"nocursor")
- cursor_drag enable cursor changes during drag.
- nocursor_drag disable cursor changes during drag.
- arrow:n set -arrow to alternate n.
- xfixes enable xfixes cursor shape mode.
- noxfixes disable xfixes cursor shape mode.
- alphacut:n set -alphacut to n.
- alphafrac:f set -alphafrac to f.
- alpharemove enable -alpharemove mode.
- noalpharemove disable -alpharemove mode.
- alphablend disable -noalphablend mode.
- noalphablend enable -noalphablend mode.
- cursorshape disable -nocursorshape mode.
- nocursorshape enable -nocursorshape mode.
- cursorpos disable -nocursorpos mode.
- nocursorpos enable -nocursorpos mode.
- xwarp enable -xwarppointer mode.
- noxwarp disable -xwarppointer mode.
- always_inject enable -always_inject mode.
- noalways_inject disable -always_inject mode.
- buttonmap:str set -buttonmap "str", empty
to disable
- dragging disable -nodragging mode.
- nodragging enable -nodragging mode.
- ncache reenable -ncache mode.
- noncache disable -ncache mode.
- ncache_size:n set -ncache size to n.
- ncache_cr enable -ncache_cr mode.
- noncache_cr disable -ncache_cr mode.
- ncache_no_moveraise enable no_moveraise mode.
- noncache_no_moveraise disable no_moveraise mode.
- ncache_no_dtchange enable ncache_no_dtchange mode.
- noncache_no_dtchange disable ncache_no_dtchange mode.
- ncache_old_wm enable ncache_old_wm mode.
- noncache_old_wm disable ncache_old_wm mode.
- ncache_no_rootpixmap enable ncache_no_rootpixmap.
- noncache_no_rootpixmap disable ncache_no_rootpixmap.
- ncache_reset_rootpixmap recheck the root pixmap, ncrp
- ncache_keep_anims enable ncache_keep_anims.
- noncache_keep_anims disable ncache_keep_anims.
- ncache_pad:n set -ncache_pad to n.
- wireframe enable -wireframe mode. same as
"wf"
- nowireframe disable -wireframe mode. same as
"nowf"
- wireframe:str enable -wireframe mode string.
- wireframe_mode:str enable -wireframe mode
string.
- wireframelocal enable wireframelocal. same as
"wfl"
- nowireframe disable wireframelocal. same as
"nowfl"
- wirecopyrect:str set -wirecopyrect string. same as
"wcr:"
- scrollcopyrect:str set -scrollcopyrect string. same
"scr"
- noscrollcopyrect disable -scrollcopyrect__mode_.
"noscr"
- scr_area:n set -scr_area to n
- scr_skip:list set -scr_skip to "list"
- scr_inc:list set -scr_inc to "list"
- scr_keys:list set -scr_keys to "list"
- scr_term:list set -scr_term to "list"
- scr_keyrepeat:str set -scr_keyrepeat to
"str"
- scr_parms:str set -scr_parms parameters.
- fixscreen:str set -fixscreen to
"str".
- noxrecord disable all use of RECORD extension.
- xrecord enable use of RECORD extension.
- reset_record reset RECORD extension (if avail.)
- pointer_mode:n set -pointer_mode to n. same as
"pm"
- input_skip:n set -input_skip to n.
- allinput enable use of -allinput mode.
- noallinput disable use of -allinput mode.
- input_eagerly enable use of -input_eagerly
mode.
- noinput_eagerly disable use of -input_eagerly
mode.
- ssltimeout:n set -ssltimeout to n.
- speeds:str set -speeds to str.
- wmdt:str set -wmdt to str.
- debug_pointer enable -debug_pointer, same as
"dp"
- nodebug_pointer disable -debug_pointer, same as
"nodp"
- debug_keyboard enable -debug_keyboard, same as
"dk"
- nodebug_keyboard disable -debug_keyboard, same as
"nodk"
- keycode:n inject keystroke 'keycode' (xmodmap
-pk)
- keycode:n,down inject 'keycode' (down=0,1)
- keysym:str inject keystroke 'keysym' (number/name)
- keysym:str,down inject 'keysym' (down=0,1)
- ptr:x,y,mask inject pointer event x, y, button-mask
- fakebuttonevent:button,down direct
XTestFakeButtonEvent.
- sleep:t sleep floating point time t.
- get_xprop:p get X property named 'p'.
- set_xprop:p:val set X property named 'p' to 'val'. p ->
id=NNN:p for hex/dec window id.
- wininfo:id get info about X window id. use 'root' for root
window, use +id for children.
- grab_state get state of pointer and keyboard grab.
- pointer_pos print XQueryPointer x,y cursor position.
- pointer_x print XQueryPointer x cursor position.
- pointer_y print XQueryPointer y cursor position.
- pointer_same print XQueryPointer ptr on same screen.
- pointer_root print XQueryPointer curr ptr rootwin.
- pointer_mask print XQueryPointer button and mods mask
- mouse_x print x11vnc's idea of cursor position.
- mouse_y print x11vnc's idea of cursor position.
- noop do nothing.
- defer:n set -defer to n ms,same as
deferupdate:n
- wait:n set -wait to n ms.
- extra_fbur:n set -extra_fbur to n.
- wait_ui:f set -wait_ui factor to f.
- setdefer:n set -setdefer to -2,-1,0,1, or
2.
- wait_bog disable -nowait_bog mode.
- nowait_bog enable -nowait_bog mode.
- slow_fb:f set -slow_fb to f seconds.
- xrefresh:f set -xrefresh to f seconds.
- readtimeout:n set read timeout to n seconds.
- nap enable -nap mode.
- nonap disable -nap mode.
- sb:n set -sb to n s, same as screen_blank:n
- fbpm disable -nofbpm mode.
- nofbpm enable -nofbpm mode.
- dpms disable -nodpms mode.
- nodpms enable -nodpms mode.
- forcedpms enable -forcedpms mode.
- noforcedpms disable -forcedpms mode.
- clientdpms enable -clientdpms mode.
- noclientdpms disable -clientdpms mode.
- noserverdpms enable -noserverdpms mode.
- serverdpms disable -noserverdpms mode.
- noultraext enable -noultraext mode.
- ultraext disable -noultraext mode.
- chatwindow enable local chatwindow mode.
- nochatwindow disable local chatwindow mode.
- chaton begin chat using local window.
- chatoff end chat using local window.
- xdamage enable xdamage polling hints.
- noxdamage disable xdamage polling hints.
- xd_area:A set -xd_area max pixel area to
"A"
- xd_mem:f set -xd_mem remembrance to
"f"
- fs:frac set -fs fraction to "frac", e.g.
0.5
- gaps:n set -gaps to n.
- grow:n set -grow to n.
- fuzz:n set -fuzz to n.
- snapfb enable -snapfb mode.
- nosnapfb disable -snapfb mode.
- rawfb:str set -rawfb mode to "str".
- uinput_accel:f set uinput_accel to f.
- uinput_thresh:n set uinput_thresh to n.
- uinput_reset:n set uinput_reset to n ms.
- uinput_always:n set uinput_always to 1/0.
- progressive:n set LibVNCServer -progressive slice
height parameter to n.
- desktop:str set -desktop name to str for new
clients.
- rfbport:n set -rfbport to n.
- macnosaver enable -macnosaver mode.
- macsaver disable -macnosaver mode.
- macnowait enable -macnowait mode.
- macwait disable -macnowait mode.
- macwheel:n set -macwheel to n.
- macnoswap enable -macnoswap mouse button mode.
- macswap disable -macnoswap mouse button mode.
- macnoresize enable -macnoresize mode.
- macresize disable -macnoresize mode.
- maciconanim:n set -maciconanim to n.
- macmenu enable -macmenu mode.
- macnomenu disable -macmenu mode.
- macuskbd enable -macuskbd mode.
- macnouskbd disable -macuskbd mode.
- httpport:n set -httpport to n.
- httpdir:dir set -httpdir to dir (and enable
http).
- enablehttpproxy enable -enablehttpproxy mode.
- noenablehttpproxy disable -enablehttpproxy
mode.
- alwaysshared enable -alwaysshared mode.
- noalwaysshared disable -alwaysshared mode. (may
interfere with other options)
- nevershared enable -nevershared mode.
- nonevershared disable -nevershared mode. (may
interfere with other options)
- dontdisconnect enable -dontdisconnect mode.
- nodontdisconnect disable -dontdisconnect mode. (may
interfere with other options)
- debug_xevents enable debugging X events.
- nodebug_xevents disable debugging X events.
- debug_xdamage enable debugging X DAMAGE mechanism.
- nodebug_xdamage disable debugging X DAMAGE mechanism.
- debug_wireframe enable debugging wireframe mechanism.
- nodebug_wireframe disable debugging wireframe
mechanism.
- debug_scroll enable debugging scrollcopy mechanism.
- nodebug_scroll disable debugging scrollcopy mechanism.
- debug_tiles enable -debug_tiles
- nodebug_tiles disable -debug_tiles
- debug_grabs enable -debug_grabs
- nodebug_grabs disable -debug_grabs
- debug_sel enable -debug_sel
- nodebug_sel disable -debug_sel
- debug_ncache enable -debug_ncache
- nodebug_ncache disable -debug_ncache
- dbg enable -dbg crash shell
- nodbg disable -dbg crash shell
- noremote disable the -remote command processing, it
cannot be turned back on.
- bcx_xattach:str This remote control command is for use with
the BARCO xattach program or the x2x program. Both of these programs are
for 'pointer and keyboard' sharing between separate X displays. In general
the two displays are usually nearby, e.g. on the same desk, and this
allows the user to share a single pointer and keyboard between them. The
user moves the mouse to an edge and then the mouse pointer appears to
'jump' to the other display screen. Thus it emulates what a single X
server would do for two screens (e.g. :0.0 and :0.1) The illusion of a
single Xserver with multiple screens is achieved by forwarding events to
the 2nd one via the XTEST extension.
- What the x11vnc bcx_xattach command does is to perform some
pointer movements to try to INDUCE xattach/x2x to 'jump' to the other
display. In what follows the ´master' display refers to the one that
when it has ´focus' it is basically doing nothing besides watching
for the mouse to go over an edge. The 'slave' display refers to the one to
which the mouse and keyboard is redirected to once an edge in the master
has been crossed. Note that the x11vnc executing the bcx_xattach command
MUST be the one connected to the *master* display.
- Also note that when input is being redirected (via XTEST)
from the master display to the slave display, the master display's pointer
and keyboard are *grabbed* by xattach/x2x. x11vnc can use this info to
verify that the master/slave mode change has taken place correctly. If you
specify the "ifneeded" option (see below) and the initial grab
state is that of the desired final state, then no pointer movements are
injected and "DONE,GRAB_OK" is returned.
- "str" must contain one of "up",
"down", "left", or "right" to indicate the
direction of the 'jump'. "str" must also contain one of
"master_to_slave" or "slave_to_master" to indicate the
type of mode change induced by the jump. Use "M2S" and
"S2M" as shorter aliases.
- "str" may be a "+" separated list of
additional tuning options. The "shift=n" option indicates an
offset shift position away from (0,0) (default 20). "final=x+y"
specifies the final position of the cursor at the end of the normal move
sequence; default 30+30. "extra_move=x+y" means to do one more
pointer move after "final" to x+y. "dt=n" sets the
sleep time in milliseconds between pointer moves (default: 40ms)
"retry=n" specifies the maximum number of retries if the grab
state change fails. "ifneeded" means to not apply the pointer
movements if the initial grab state is that of the desired final state.
"nograbcheck" means to not check if the grab state changed as
expected and only apply the pointer movements (default is to check the
grab states.)
- If you do not specify "up", etc., to bcx_xattach
nothing will be attempted and the command returns the string
FAIL,NO_DIRECTION_SPECIFIED. If you do not specify
"master_to_slave" or "M2S", etc., to bcx_xattach
nothing will be attempted and the command returns the string
FAIL,NO_MODE_CHANGE_SPECIFIED.
- Otherwise, the returned string will contain
"DONE". It will be "DONE,GRAB_OK" if the grab state
changed as expected (or if "ifneeded" was supplied and the
initial grab state was already the desired one.) If the initial grab state
was incorrect, but the final grab state was correct then it is
"DONE,GRAB_FAIL_INIT". If the initial grab state was correct,
but the final grab state was incorrect then it is
"DONE,GRAB_FAIL_FINAL". If both are incorrect it will be
"DONE,GRAB_FAIL". Under grab failure the string will be followed
by ":p1,k1-p2,k2" where p1,k1 indicates the initial pointer and
keyboard grab states and p2,k2 the final ones. If GRAB_FAIL or
GRAB_FAIL_FINAL occurs, the action will be retried up to 3 times; trying
to reset the state and sleeping a bit between each try. Set retry=n to
adjust the number of retries, zero to disable retries.
- Examples: -R bcx_xattach:down+M2S -R
bcx_xattach:up+S2M -R bcx_xattach:up+S2M+nograbcheck+dt=30
-R bcx_xattach:down+M2S+extra_move=100+100
- or use -Q instead of -R to retrieve the
result text.
- End of the bcx_xattach:str description.
- The vncconnect(1) command from standard VNC
distributions may also be used if string is prefixed with "cmd="
E.g. 'vncconnect cmd=stop'. Under some circumstances xprop(1) can
used if it supports -set (see the FAQ).
- If "-connect /path/to/file" has
been supplied to the running x11vnc server then that file can be used as a
communication channel (this is the only way to remote control one of many
x11vnc's polling the same X display) Simply run: 'x11vnc -connect
/path/to/file -remote ...' or you can directly write to the file
via something like: "echo cmd=stop > /path/to/file",
etc.
-query variable
- Like -remote, except just query the value of
variable. " -Q" is an alias for
"-query". Multiple queries can be done by separating
variables by commas, e.g. -query var1,var2. The results come back
in the form ans=var1:value1,ans=var2:value2,... to the standard output. If
a variable is read-only, it comes back with prefix "aro="
instead of "ans=".
- Some -remote commands are pure actions that do not
make sense as variables, e.g. "stop" or "disconnect",
in these cases the value returned is "N/A". To direct a query
straight to the X11VNC_REMOTE property or connect file use
"qry=..." instead of "cmd=..."
- ans= stop quit exit shutdown ping resend_cutbuffer
resend_clipboard resend_primary blacken zero refresh reset close
disconnect id_cmd id sid waitmapped nowaitmapped clip flashcmap
noflashcmap shiftcmap truecolor notruecolor overlay nooverlay
overlay_cursor overlay_yescursor nooverlay_nocursor nooverlay_cursor
nooverlay_yescursor overlay_nocursor 8to24 no8to24 8to24_opts 24to32
no24to32 visual scale scale_cursor viewonly noviewonly shared noshared
forever noforever once timeout tightfilexfer notightfilexfer ultrafilexfer
noultrafilexfer rfbversion deny lock nodeny unlock avahi mdns zeroconf
noavahi nomdns nozeroconf connect proxy allowonce allow noipv6 ipv6 noipv4
ipv4 no6 6 localhost nolocalhost listen lookup nolookup accept afteraccept
gone shm noshm flipbyteorder noflipbyteorder onetile noonetile solid_color
solid nosolid blackout xinerama noxinerama xtrap noxtrap xrandr noxrandr
xrandr_mode rotate padgeom quiet q noquiet modtweak nomodtweak xkb noxkb
capslock nocapslock skip_lockkeys noskip_lockkeys skip_keycodes
sloppy_keys nosloppy_keys skip_dups noskip_dups add_keysyms noadd_keysyms
clear_mods noclear_mods clear_keys noclear_keys clear_all clear_locks
keystate remap repeat norepeat fb nofb bell nobell sendbell sel nosel
primary noprimary setprimary nosetprimary clipboard noclipboard
setclipboard nosetclipboard seldir cursorshape nocursorshape cursorpos
nocursorpos cursor_drag nocursor_drag cursor show_cursor noshow_cursor
nocursor arrow xfixes noxfixes xdamage noxdamage xd_area xd_mem alphacut
alphafrac alpharemove noalpharemove alphablend noalphablend xwarppointer
xwarp noxwarppointer noxwarp always_inject noalways_inject buttonmap
dragging nodragging ncache_cr noncache_cr ncache_no_moveraise
noncache_no_moveraise ncache_no_dtchange noncache_no_dtchange
ncache_no_rootpixmap noncache_no_rootpixmap ncache_reset_rootpixmap ncrp
ncache_keep_anims noncache_keep_anims ncache_old_wm noncache_old_wm
ncache_pad ncache noncache ncache_size debug_ncache nodebug_ncache
wireframe_mode wireframe wf nowireframe nowf wireframelocal wfl
nowireframelocal nowfl wirecopyrect wcr nowirecopyrect nowcr scr_area
scr_skip scr_inc scr_keys scr_term scr_keyrepeat scr_parms scrollcopyrect
scr noscrollcopyrect noscr fixscreen noxrecord xrecord reset_record
pointer_mode pm input_skip allinput noallinput input_eagerly
noinput_eagerly input grabkbd nograbkbd grabptr nograbptr grabalways
nograbalways grablocal client_input ssltimeout speeds wmdt debug_pointer
dp nodebug_pointer nodp debug_keyboard dk nodebug_keyboard nodk keycode
keysym ptr fakebuttonevent sleep get_xprop set_xprop wininfo bcx_xattach
deferupdate defer setdefer extra_fbur wait_ui wait_bog nowait_bog slow_fb
xrefresh wait readtimeout nap nonap sb screen_blank fbpm nofbpm dpms
nodpms clientdpms noclientdpms forcedpms noforcedpms noserverdpms
serverdpms noultraext ultraext chatwindow nochatwindow chaton chatoff fs
gaps grow fuzz snapfb nosnapfb rawfb uinput_accel uinput_thresh
uinput_reset uinput_always progressive rfbport http nohttp httpport
httpdir enablehttpproxy noenablehttpproxy alwaysshared noalwaysshared
nevershared noalwaysshared dontdisconnect nodontdisconnect desktop
debug_xevents nodebug_xevents debug_xevents debug_xdamage nodebug_xdamage
debug_xdamage debug_wireframe nodebug_wireframe debug_wireframe
debug_scroll nodebug_scroll debug_scroll debug_tiles dbt nodebug_tiles
nodbt debug_tiles debug_grabs nodebug_grabs debug_sel nodebug_sel dbg
nodbg macnosaver macsaver nomacnosaver macnowait macwait nomacnowait
macwheel macnoswap macswap nomacnoswap macnoresize macresize nomacnoresize
maciconanim macmenu macnomenu nomacmenu macuskbd nomacuskbd noremote
- aro= noop display vncdisplay icon_mode autoport loop loopbg
desktopname guess_desktop guess_dbus http_url auth xauth users rootshift
clipshift scale_str scaled_x scaled_y scale_numer scale_denom scale_fac_x
scale_fac_y scaling_blend scaling_nomult4 scaling_pad scaling_interpolate
inetd privremote unsafe safer nocmds passwdfile unixpw unixpw_nis
unixpw_list ssl ssl_pem sslverify stunnel stunnel_pem https httpsredir
usepw using_shm logfile o flag rmflag rc norc h help V version lastmod bg
sigpipe threads readrate netrate netlatency pipeinput clients client_count
pid ext_xtest ext_xtrap ext_xrecord ext_xkb ext_xshm ext_xinerama
ext_overlay ext_xfixes ext_xdamage ext_xrandr rootwin num_buttons
button_mask mouse_x mouse_y grab_state pointer_pos pointer_x pointer_y
pointer_same pointer_root pointer_mask bpp depth indexed_color dpy_x dpy_y
wdpy_x wdpy_y off_x off_y cdpy_x cdpy_y coff_x coff_y rfbauth passwd
viewpasswd
-QD variable
- Just like -query variable, but returns the default
value for that parameter (no running x11vnc server is consulted)
-sync
- By default -remote commands are run asynchronously,
that is, the request is posted and the program immediately exits. Use
-sync to have the program wait for an acknowledgement from the
x11vnc server that command was processed (somehow). On the other hand
-query requests are always processed synchronously because they
have to wait for the answer.
- Also note that if both -remote and -query
requests are supplied on the command line, the -remote is processed
first (synchronously: no need for -sync), and then the
-query request is processed in the normal way. This allows for a
reliable way to see if the -remote command was processed by
querying for any new settings. Note however that there is timeout of a few
seconds (see the next paragraph) so if the x11vnc takes longer than that
to process the requests the requester will think that a failure has taken
place.
- The default is to wait 3.5 seconds. Or if cmd=stop only 1.0
seconds. If cmd matches 'script:' then it will wait up to 10.0 seconds.
Set X11VNC_SYNC_TIMEOUT to the number of seconds you want it to wait.
-query_retries str
- If a query fails to get a response from an x11vnc server,
retry up to n times. str is specified as n[:t][/match] Optionally
the delay between tries may be specified by "t" a floating point
time (default 0.5 seconds.) Note: the response is not checked for validity
or whether it corresponds to the query sent. The query
"ping:mystring" may be used to help uniquely identify the query.
Optionally, a matching string after a "/" will be used to check
the result text. Up to n retries will take place until the matching string
is found in the output text. If the match string is never found the
program's exit code is 1; if the match is found it exits with 0. Note that
there may be stdout printed for each retry (i.e. multiple lines printed
out to stdout.) Example: -query_retries 4:1.5/grab_state
-remote_prefix str
- Enable a remote-control communication channel for connected
VNC clients. str is a non-empty string. If a VNC client sends rfbCutText
having the prefix str then the part after it is processed as though
it were sent via 'x11vnc -remote ...'. If it begins with neither
'cmd=' nor 'qry=' then 'qry=' is assumed. Any corresponding output text
for that remote control command is sent back to all client as rfbCutText.
The returned output is also prefixed with str. Example:
-remote_prefix DO_THIS:
- Note that enabling -remote_prefix allows the remote
VNC viewers to run x11vnc -remote commands. Do not use this option
if they are not to be trusted.
-noremote, -yesremote
- Do not process any remote control commands or queries. Do
process remote control commands or queries. Default:
-yesremote
- A note about security wrt remote control commands. If
someone can connect to the X display and change the property
X11VNC_REMOTE, then they can remotely control x11vnc. Normally access to
the X display is protected. Note that if they can modify X11VNC_REMOTE on
the X server, they have enough permissions to also run their own x11vnc
and thus have complete control of the desktop. If the "
-connect /path/to/file" channel is being used,
obviously anyone who can write to /path/to/file can remotely control
x11vnc. So be sure to protect the X display and that file's write
permissions. See -privremote below.
- If you are paranoid and do not think -noremote is
enough, to disable the X11VNC_REMOTE property channel completely use
-novncconnect, or use the -safer option that shuts many
things off.
-unsafe
- A few remote commands are disabled by default (currently:
id:pick, accept:<cmd>, gone:<cmd>, and
rawfb:setup:<cmd>) because they are associated with running external
programs. If you specify -unsafe, then these remote-control
commands are allowed. Note that you can still specify these parameters on
the command line, they just cannot be invoked via remote-control.
-safer
- Equivalent to: -novncconnect -noremote and
prohibiting -gui and the -connect file. Shuts off
communcation channels.
-privremote
- Perform some sanity checks and disable remote-control
commands if it appears that the X DISPLAY and/or connectfile can be
accessed by other users. Once remote-control is disabled it cannot be
turned back on.
-nocmds
- No external commands (e.g. system(3) ,
popen(3) , exec(3) ) will be run at all.
-allowedcmds list
- list contains a comma separated list of the only
external commands that can be run. The full list of associated options
is:
- stunnel, ssl, unixpw, WAIT, zeroconf, id, accept,
afteraccept, gone, pipeinput, v4l-info, rawfb-setup, dt, gui, ssh,
storepasswd, passwdfile, custom_passwd, findauth, crash.
- See each option's help to learn the associated external
command. Note that the -nocmds option takes precedence and disables
all external commands.
-deny_all
- For use with -remote nodeny: start out denying all
incoming clients until " -remote nodeny" is used
to let them in.
These options are passed to LibVNCServer:
-rfbport port
- TCP port for RFB protocol
-rfbwait time
- max time in ms to wait for RFB client
-rfbauth passwd-file
- use authentication on RFB protocol (use 'x11vnc
-storepasswd pass file' to create a password file)
-rfbversion 3.x
- Set the version of the RFB we choose to advertise
-permitfiletransfer
- permit file transfer support
-passwd plain-password
- use authentication (use plain-password as password, USE AT
YOUR RISK)
-deferupdate time
- time in ms to defer updates (default 40)
-deferptrupdate time
- time in ms to defer pointer updates (default none)
-desktop name
- VNC desktop name (default "LibVNCServer")
-alwaysshared
- always treat new clients as shared
-nevershared
- never treat new clients as shared
-dontdisconnect
- don't disconnect existing clients when a new non-shared
connection comes in (refuse new connection instead)
-httpdir dir-path
- enable http server using dir-path home
-httpport portnum
- use portnum for http connection
-enablehttpproxy
- enable http proxy support
-progressive height
- enable progressive updating for slow links
-listen ipaddr
- listen for connections only on network interface with addr
ipaddr. '-listen localhost' and hostname work too.
libvncserver-tight-extension options:
-disablefiletransfer
- disable file transfer
-ftproot string
- set ftp root
FILES¶
$HOME/.x11vncrc,
$HOME/.Xauthority
ENVIRONMENT¶
DISPLAY,
XAUTHORITY,
HOME
The following are set for the auxiliary commands run by
-accept,
-gone and other cases:
RFB_CLIENT_IP,
RFB_CLIENT_PORT,
RFB_SERVER_IP,
RFB_SERVER_PORT,
RFB_X11VNC_PID,
RFB_CLIENT_ID,
RFB_CLIENT_COUNT,
RFB_MODE RFB_STATE
RFB_LOGIN_VIEWONLY RFB_LOGIN_TIME RFB_CURRENT_TIME
RFB_USERNAME RFB_SSL_CLIENT_CERT
SEE ALSO¶
vncviewer(1),
vncpasswd(1),
vncconnect(1),
vncserver(1),
Xvnc(1),
xev(1),
xdpyinfo(1),
xwininfo(1),
xprop(1),
xmodmap(1),
xrandr(1),
Xserver(1),
xauth(1),
xhost(1),
Xsecurity(7),
xmessage(1),
XGetImage(3X11),
ipcrm(1),
inetd(1),
xdm(1),
gdm(1),
kdm(1),
ssh(1),
stunnel(8),
su(1),
http://www.tightvnc.com,
http://www.realvnc.com,
http://www.karlrunge.com/x11vnc/,
http://www.karlrunge.com/x11vnc/#faq
AUTHORS¶
x11vnc was written by Karl J. Runge <runge@karlrunge.com>, it is part of
the LibVNCServer project <
http://sf.net/projects/libvncserver>. This
manual page is based one the one written by Ludovic Drolez
<ldrolez@debian.org>, for the Debian project (both may be used by
others).