NAME¶
bootptab - Internet Bootstrap Protocol server database
DESCRIPTION¶
The
bootptab file is the configuration database file for
bootpd,
the Internet Bootstrap Protocol server. It's format is similar to that of
termcap(5) in which two-character case-sensitive tag symbols are used
to represent host parameters. These parameter declarations are separated by
colons (:), with a general format of:
hostname:tg=value... :tg=value... :tg=value. ...
where
hostname is the actual name of a bootp client (or a "dummy
entry"), and
tg is a two-character tag symbol. Dummy entries have
an invalid hostname (one with a "." as the first character) and are
used to provide default values used by other entries via the
tc=.dummy-entry mechanism. Most tags must be followed by an
equals-sign and a value as above. Some may also appear in a boolean form with
no value (i.e. :
tg:). The currently recognized tags are:
bf Bootfile
bs Bootfile size in 512-octet blocks
cs Cookie server address list
df Merit dump file
dl DHCP lease time in seconds
dn Domain name
ds Domain name server address list
ef Extension file
ex York ex option (huh?)
gw Gateway address list
ha Host hardware address
hd Bootfile home directory
hn Send client's hostname to client
ht Host hardware type (see Assigned Numbers RFC)
im Impress server address list
ip Host IP address
lg Log server address list
lp LPR server address list
ms Message size
ns IEN-116 name server address list
nt NTP (time) Server (RFC 1129)
ra Reply address override
rl Resource location protocol server address list
rp Root path to mount as root
sa TFTP server address client should use
sm Host subnet mask
sw Swap server address
tc Table continuation (points to similar "template" host entry)
td TFTP root directory used by "secure" TFTP servers
to Time offset in seconds from UTC
ts Time server address list
vm Vendor magic cookie selector
yd YP (NIS) domain name
ys YP (NIS) server address
There is also a generic tag,
Tn, where
n is an
RFC1084 vendor field tag number. Thus it is possible to immediately take
advantage of future extensions to RFC1084 without being forced to modify
bootpd first. Generic data may be represented as either a stream of
hexadecimal numbers or as a quoted string of ASCII characters. The length of
the generic data is automatically determined and inserted into the proper
field(s) of the RFC1084-style bootp reply.
The following tags take a whitespace-separated list of IP addresses:
cs,
ds,
gw,
im,
lg,
lp,
ns,
nt,
ra,
rl, and
ts. The
ip,
sa,
sw,
sm, and
ys tags each take a single IP address. All IP addresses
are specified in standard Internet "dot" notation and may use
decimal, octal, or hexadecimal numbers (octal numbers begin with 0,
hexadecimal numbers begin with '0x' or '0X'). Any IP addresses may
alternatively be specified as a hostname, causing
bootpd to lookup the
IP address for that host name using
gethostbyname(3). If the
ip
tag is not specified,
bootpd will determine the IP address using the
entry name as the host name. (Dummy entries use an invalid host name to avoid
automatic IP lookup.)
The
ht tag specifies the hardware type code as either an unsigned
decimal, octal, or hexadecimal integer or one of the following symbolic names:
ethernet or
ether for 10Mb Ethernet,
ethernet3 or
ether3 for 3Mb experimental Ethernet,
ieee802,
tr, or
token-ring for IEEE 802 networks,
pronet for Proteon ProNET
Token Ring, or
chaos,
arcnet, or
ax.25 for Chaos, ARCNET,
and AX.25 Amateur Radio networks, respectively. The
ha tag takes a
hardware address which may be specified as a host name or in numeric form.
Note that the numeric form
must be specified in hexadecimal; optional
periods and/or a leading '0x' may be included for readability. The
ha
tag must be preceded by the
ht tag (either explicitly or implicitly;
see
tc below). If the hardware address is not specified and the type is
specified as either "ethernet" or "ieee802", then
bootpd will try to determine the hardware address using
ether_hton(3).
The hostname, home directory, and bootfile are ASCII strings which may be
optionally surrounded by double quotes ("). The client's request and the
values of the
hd and
bf symbols determine how the server fills
in the bootfile field of the bootp reply packet.
If the client provides a file name it is left as is. Otherwise, if the
bf
option is specified its value is copied into the reply packet. If the
hd option is specified as well, its value is prepended to the boot file
copied into the reply packet. The existence of the boot file is checked only
if the
bs=auto option is used (to determine the boot file size).
A reply may be sent whether or not the boot file exists.
Some newer versions of
tftpd(8) provide a security feature to change
their root directory using the
chroot(2) system call. The
td tag
may be used to inform
bootpd of this special root directory used by
tftpd. (One may alternatively use the
bootpd -c
chdir option.) The
hd tag is actually relative to the root
directory specified by the
td tag. For example, if the real absolute
path to your BOOTP client bootfile is
/tftpboot/bootfiles/bootimage,
and
tftpd uses
/tftpboot as its "secure" directory,
then specify the following in
bootptab:
:td=/tftpboot:hd=/bootfiles:bf=bootimage:
If your bootfiles are located directly in /tftpboot, use:
:td=/tftpboot:hd=/:bf=bootimage:
The
sa tag may be used to specify the IP address of the particular TFTP
server you wish the client to use. In the absence of this tag,
bootpd
will tell the client to perform TFTP to the same machine
bootpd is
running on.
The time offset
to may be either a signed decimal integer specifying the
client's time zone offset in seconds from UTC, or the keyword
auto
which uses the server's time zone offset. Specifying the
to symbol as a
boolean has the same effect as specifying
auto as its value.
The bootfile size
bs may be either a decimal, octal, or hexadecimal
integer specifying the size of the bootfile in 512-octet blocks, or the
keyword
auto which causes the server to automatically calculate the
bootfile size at each request. As with the time offset, specifying the
bs symbol as a boolean has the same effect as specifying
auto as
its value.
The vendor magic cookie selector (the
vm tag) may take one of the
following keywords:
auto (indicating that vendor information is
determined by the client's request),
rfc1048 or
rfc1084 (which
always forces an RFC1084-style reply), or
cmu (which always forces a
CMU-style reply).
The
hn tag is strictly a boolean tag; it does not take the usual
equals-sign and value. It's presence indicates that the hostname should be
sent to RFC1084 clients.
Bootpd attempts to send the entire hostname
(including domain) as it is specified in the configuration file; if this will
not fit into the reply packet, the name is shortened to just the host field
(up to the first period, if present) and then tried. In no case is an
arbitrarily-truncated hostname sent (if nothing reasonable will fit, nothing
is sent).
Often, many host entries share common values for certain tags (such as name
servers, etc.). Rather than repeatedly specifying these tags, a full
specification can be listed for one host entry and shared by others via the
tc (table continuation) mechanism. Often, the template entry is a dummy
host which doesn't actually exist and never sends bootp requests. This feature
is similar to the
tc feature of
termcap(5) for similar
terminals. Note that
bootpd allows the
tc tag symbol to appear
anywhere in the host entry, unlike
termcap which requires it to be the
last tag. Information explicitly specified for a host always overrides
information implied by a
tc tag symbol, regardless of its location
within the entry. The value of the
tc tag may be the hostname or IP
address of any host entry previously listed in the configuration file.
Sometimes it is necessary to delete a specific tag after it has been inferred
via
tc. This can be done using the construction
tag@
which removes the effect of
tag as in
termcap(5). For example,
to completely undo an IEN-116 name server specification, use ":ns@:"
at an appropriate place in the configuration entry. After removal with
@, a tag is eligible to be set again through the
tc mechanism.
Blank lines and lines beginning with "#" are ignored in the
configuration file. Host entries are separated from one another by newlines; a
single host entry may be extended over multiple lines if the lines end with a
backslash (\). It is also acceptable for lines to be longer than 80
characters. Tags may appear in any order, with the following exceptions: the
hostname must be the very first field in an entry, and the hardware type must
precede the hardware address.
An example
/etc/bootptab file follows:
# Sample bootptab file (domain=andrew.cmu.edu)
.default:\
:hd=/usr/boot:bf=null:\
:ds=netserver, lancaster:\
:ns=pcs2, pcs1:\
:ts=pcs2, pcs1:\
:sm=255.255.255.0:\
:gw=gw.cs.cmu.edu:\
:hn:to=-18000:
carnegie:ht=6:ha=7FF8100000AF:tc=.default:
baldwin:ht=1:ha=0800200159C3:tc=.default:
wylie:ht=1:ha=00DD00CADF00:tc=.default:
arnold:ht=1:ha=0800200102AD:tc=.default:
bairdford:ht=1:ha=08002B02A2F9:tc=.default:
bakerstown:ht=1:ha=08002B0287C8:tc=.default:
# Special domain name server and option tags for next host
butlerjct:ha=08002001560D:ds=128.2.13.42:\
:T37=0x12345927AD3BCF:\
:T99="Special ASCII string":\
:tc=.default:
gastonville:ht=6:ha=7FFF81000A47:tc=.default:
hahntown:ht=6:ha=7FFF81000434:tc=.default:
hickman:ht=6:ha=7FFF810001BA:tc=.default:
lowber:ht=1:ha=00DD00CAF000:tc=.default:
mtoliver:ht=1:ha=00DD00FE1600:tc=.default:
FILES¶
- /etc/bootptab
- The definition file
SEE ALSO¶
bootpd(8),
tftpd(8),
DARPA Internet Request For Comments RFC951, RFC1048, RFC1084, Assigned
Numbers