BOOTPD(1M) (Network Compatibility) BOOTPD(1M)
NAME
bootpd - Internet Boot Protocol server
SYNOPSIS
/etc/bootpd [ -s -t timeout -d ] [ configfile [ dumpfile ] ]
DESCRIPTION
Bootpd implements an Internet Boot Protocol server as defined
in RFC951 and RFC1048. It is normally run by /etc/inetd
by including the following line in the file /etc/inetd.conf :
bootps dgram udp wait root /etc/bootpd bootpd
This causes bootpd to be started only when a boot request arrives.
If bootpd does not receive another boot request within fifteen
minutes of the last one it received, it will exit to conserve
system resources. The -t switch may be used to specify a different
timeout value in minutes (e.g. -t20). A timeout value of zero means
forever.
It is also possible to run bootpd in a standalone configuration
using the -s switch (for example, at boot time from /etc/rc.local).
This is probably the desired mode of operation for large network
installations with many hosts. In this case, the -t switch has no
effect since bootpd will never exit.
Each instance of the -d switch increases the level of debugging output.
Upon startup, bootpd first reads its configuration file, /etc/bootptab,
and then begins listening for BOOTREQUEST packets. The configuration
file has a format 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(:). The general
format is:
hostname:tg=value. . . :tg=value. . . :tg=value. . . ."
where hostname is the actual name of a bootp client and tg is a
two-character tag symbol. 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
ds Domain name server address list
gw Gateway address list
ha Host hardware address
hd Bootfile home directory
hn Send hostname
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
ns IEN-116 name server address list
rl Resource location protocol server address list
sm Host subnet mask
tc Table continuation (points to similar, "template"
host entry)
to Time offset in seconds from UTC
ts Time server address list
vm Vendor magic cookie selector
There is also a generic tag, T n , where n is an RFC1048 vendor field
tag number. Thus it is possible to immediately take advantage of
future extensions to RFC1048 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 RFC1048-style bootp reply.
The following tags take a whitespace-separated list of IP addresses:
cs , ds , gw , im , lg , lp , ns , rl , and ts.
The ip and sm 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').
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 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).
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 specifies an absolute pathname and that file exists on
the server machine, that pathname is returned in the reply packet.
If the file cannot be found, the request is discarded; no reply is
sent. If the client specifies a relative pathname, a full pathname
is formed by prepending the value of the hd tag and testing for
existence of the file. If the hd tag is not supplied in the
configuration file or if the resulting boot file cannot be found,
then the request is discarded.
Clients which specify null boot files will always elicit a reply from
the server. The exact reply will again depend upon the hd and bf
tags. If the bf tag gives an absolute pathname and the file exists,
that pathname is returned in the reply packet. Otherwise, if the hd
and bf tags together specify an accessible file, that filename is
returned in the reply. If a complete filename cannot be determined or
the file does not exist, the reply will contain a zeroed-out bootfile
field.
In all these cases, existence of the file means that, in addition to
actually being present, the file must have its public read access bit
set, since this is required by tftpd(1M) to permit the file
transfer. Also, all filenames are first tried as filename.hostname
and then simply as filename, thus providing for individual per-host
bootfiles.
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 (which always forces an RFC1048-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 RFC1048 clients. Bootpd attempts to send the
entire hostname 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
default1:\
:hd=/usr/boot:bf=null:\
:ds=128.2.35.50 128.2.13.21:\
:ns=0x80020b4d 0x80020ffd:\
:ts=0x80020b4d 0x80020ffd:\
:sm=255.255.0.0:gw=0x8002fe24:\
:hn:vm=auto:to=-18000:\
:T37=0x12345927AD3BCF:T99="Special ASCII string":
carnegie:ht=6:ha=7FF8100000AF:ip=128.2.11.1:tc=default1:
baldwin:ht=1:ha=0800200159C3:ip=128.2.11.10:tc=default1:
wylie:ht=1:ha=00DD00CADF00:ip=128.2.11.100:tc=default1:
arnold:ht=1:ha=0800200102AD:ip=128.2.11.102:tc=default1:
bairdford:ht=1:ha=08002B02A2F9:ip=128.2.11.103:tc=default1:
bakerstown:ht=1:ha=08002B0287C8:ip=128.2.11.104:tc=default1:
# Special domain name server for next host
butlerjct:ht=1:ha=08002001560D:ip=128.2.11.108:ds=128.2.13.42:\
:tc=default1:
gastonville:ht=6:ha=7FFF81000A47:ip=128.2.11.115:tc=default1:
hahntown:ht=6:ha=7FFF81000434:ip=128.2.11.117:tc=default1:
hickman:ht=6:ha=7FFF810001BA:ip=128.2.11.118:tc=default1:
lowber:ht=1:ha=00DD00CAF000:ip=128.2.11.121:tc=default1:
mtoliver:ht=1:ha=00DD00FE1600:ip=128.2.11.122:tc=default1:
Bootpd looks in /etc/services to find the port numbers it should use.
Two entries are extracted:
bootps -- the bootp server listening port, and
bootpc -- the destination port used to reply to clients.
If the port numbers cannot be determined this way, they are assumed to
be 67 for the server and 68 for the client.
Bootpd rereads its configuration file when it receives a hangup
signal, SIGHUP, or when it receives a bootp request packet and detects
that the file has been updated. Hosts may be added, deleted or modified
when the configuration file is reread. If bootpd is compiled
with the -DDEBUG option, receipt of a SIGUSR1 signal causes it to dump
its memory-resident database to the file /etc/bootpd.dump or the
command-line-specified dumpfile.
FILES
/etc/bootptab
/etc/bootpd.dump
/etc/services
BUGS
Individual host entries must not exceed 1024 characters.
HISTORY
22-Jan-86 Bill Croft at Stanford University
Created.
30-Jul-86 David Kovar at Carnegie Mellon University
Modified to CMU specifications.
24-Jul-87 Drew D. Perkins at Carnegie Mellon University
Modified to use syslog. Added debugging dumps.
Other bug fixes.
17-Jul-88 Walter L. Wimer at Carnegie Mellon University
Added vendor information to conform to RFC1048.
Adopted termcap-like file format to allow variable data.
SEE ALSO
inetd(1M);
DARPA Internet Request For Comments RFC951, RFC1048, RFC1084,
Assigned Numbers