NAME¶
ocat - OnionCat creates a transparent IPv6 layer on top of Tor's hidden
services.
gcat - GarliCat is like OnionCat but it works with I2P instead of Tor.
SYNOPSIS¶
ocat -i
onion_id (1st form)
ocat -o
IPv6_address (2nd form)
ocat [
OPTION]
onion_id (3rd form)
ocat -R [
OPTION]
(4th form)
gcat [
OPTION]
i2p_id (5th form)
DESCRIPTION¶
OnionCat creates a transparent IPv6 layer on top of Tor's hidden services or
I2P's tunnels. It transmits any kind of IP-based data transparently through
the Tor/I2P network on a location hidden basis. You can think of it as a
peer-to-peer VPN between hidden services.
OnionCat is a stand-alone application which runs in userland and is a connector
between Tor/I2P and the local OS. Any protocol which is based on IP can be
transmitted. Of course, UDP and TCP (and probably ICMP) are the most important
ones but all other protocols can also be forwarded through it.
OnionCat opens a TUN device and assigns an IPv6 address to it. All packets
forwarded to the TUN device by the kernel are forwarded by OnionCat to other
OnionCats listening on Tor's hidden service ports or I2P's server tunnels. The
IPv6 address depends on the
onion_id or the i2p_id, respectively. The
onion_id is the hostname of the locally configured hidden service (see
tor(8)). Depending on the configuration of Tor the
onion_id
usually can be found at
/var/lib/tor/hidden_service/hostname or similar
location. The
i2p_id is the 80 bit long Base32 encoded hostname of the
I2P server tunnel.
OPTIONS¶
- -4
- Enable IPv4 forwarding. See http://www.cypherpunk.at/onioncat/wiki/IPv4
for further information on IPv4.
Native IPv4 forwarding is deprecated. The recommended solution for IPv4
forwarding is to build a IPv4-through-IPv6 tunnel through OnionCat.
- -a
- OnionCat creates a log file at $HOME/.ocat/connect_log. All incoming
connects are logged to that file. $HOME is determined from the user under
which OnionCat runs (see option -u).
- -b
- Run OnionCat in background. This is default. OnionCat will detach from a
running shell and close standard IO if no log file is given with option
-L.
- -B
- Run OnionCat in foreground. OnionCat will log to stderr by default.
- -C
- Disable the local controller interface. The controller interfaces listens
on localhost (127.0.0.1 and ::1 port 8066) for incoming connections. It's
currently used for debugging purpose and not thread-safe and does not have
any kind of authentication or authorization mechanism. Hence, it should
not be used in production environments.
- -d n
- Set debug level to n. Default = 7 which is maximum. Debug output
will only be created if OnionCat was compiled with option DEBUG (i.e.
configure was run with option --enable-debug).
- -f config file
- Read initial configuration from config file.
- -h
- Display short usage message and shows options.
- -i
- Convert onion_id to IPv6 address and exit.
- -I
- Run OnionCat in GarliCat mode. Using this option is identical to running
OnionCat with the command name gcat.
- -l [ip:]port
- Bind Onioncat to specific ip and/or port number for
incoming connections. It defaults to 127.0.0.1:8060. This option could be
set multiple times. IPv6 addresses must be given in square brackets.
The parameter "none" deactivates the listener completely.
This is for special purpose only and shall not be used in regular
operation.
- -L log_file
- Log output to log_file. If option is omitted, OnionCat logs to
syslog if running in background or to stderr if running in foreground. If
syslogging is desired while running in foreground, specify the special
file name "syslog" as log file.
- -o IPv6 address
- Convert IPv6 address to onion_id and exit program.
- -p
- Use TAP device instead of TUN device. There are a view differences. See
TAP DEVICE later.
- -P [pid file]
- Create pid file at pid_file. If the option parameter is
omitted OC will create a pid file at /var/run/ocat.pid. In the
latter case it MUST NOT be the last option in the list of options.
- -r
- Run OnionCat as root and do not change user id (see option
-u).
- -R
- Use this option only if you really know what you do! OnionCat generates a
random local onion_id. With this option it is not necessary to add a
hidden service to the Tor configuration file torrc. One might use
OnionCat services within Tor as usually but it is NOT possible to receive
incoming connections. If you plan to also receive connections (e.g.
because you provide a service or you use software which opens sockets for
incoming connections like Bitorrent) you MUST configure a hidden service
and supply its hostname to OnionCat on the command line. Please note that
this option does only work if the remote OC does not run in unidirectional
mode which is default since SVN version 555 (see option -U).
- -s port
- Set OnionCat's virtual hidden service port to port. This should
usually not be changed.
- -t (IP|[IP:]port)
- Set Tor SOCKS IP and/or port. If no IP is specified
127.0.0.1 will be used, if no port is specified 9050 will be used
as defaults. IPv6 addresses must be escaped by square brackets.
The special parameter "none" disables OnionCat from making
outbound connections. This shall be used only in special test
scenarios.
- -T tun_dev
- TUN device file to open for creation of TUN interface. It defaults to
/dev/net/tun on Linux and /dev/tun0 on most other OSes, or /dev/tap0 if
TAP mode is in use. Setup of a TUN device needs root permissions. OnionCat
automatically changes userid after the TUN device is set up
correctly.
- -U
- Deactivate unidirectional mode. Before SVN version 555 OnionCat ran only
in bidirectional mode. This is that a connection to another OC was used
for outgoing and incoming packets. Since this could be a security
risk under certain conditions, unidirectional mode was implemented in SVN
r555 and set to default. With this option bidirectional mode can be
enabled again. Please note that this does not interoperate with option
-R if the remote OC is working in unidirectional mode.
- -u username
- username under which ocat should run. The uid is changed as soon as
possible after tun device setup.
TAP DEVICE¶
Usually OnionCat opens a TUN device which is a layer 3 interface. With option
-p OnionCat opens a TAP device instead which is a virtual ethernet
(layer 2) interface.
NOTES¶
This man page is still not finished...
FILES¶
$HOME/.ocat/connect_log
AUTHOR¶
Concepts, software, and man page written by Bernhard R. Fischer
<bf@abenteuerland.at>. Package maintenance and additional support by
Ferdinand Haselbacher, Daniel Haslinger <creo-ocat@blackmesa.at>, and
Wim Gaethofs.
SEE ALSO¶
OnionCat project page
http://www.cypherpunk.at/onioncat/
Tor project homepage
http://www.torproject.org/
I2P project homepage
http://www.i2p2.de/
COPYRIGHT¶
Copyright 2008-2009 Bernhard R. Fischer.
This file is part of OnionCat.
OnionCat is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, version 3 of the License.
OnionCat is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
OnionCat. If not, see <
http://www.gnu.org/licenses/>.