BOOTPD(8) System Manager's Manual BOOTPD(8)
bootpd, bootpgw - Internet Boot Protocol server/gateway
bootpd [ -i -s -t timeout -d level -c chdir-path ] [ bootptab [ dumpfile ] ]
bootpgw [ -i -s -t timeout -d level ] server
Bootpd implements an Internet Bootstrap Protocol (BOOTP) server as defined in RFC951, RFC1532, and RFC1533. Bootpgw implements a simple
BOOTP gateway which can be used to forward requests and responses between clients on one subnet and a BOOTP server (i.e. bootpd) on
another subnet. While either bootpd or bootpgw will forward BOOTREPLY packets, only bootpgw will forward BOOTREQUEST packets.
One host on each network segment is normally configured to run either bootpd or bootpgw from inetd by including one of the following lines
in the file /etc/inetd.conf:
bootps dgram udp wait root /usr/sbin/bootpd bootpd bootptab
bootps dgram udp wait root /usr/sbin/bootpgw bootpgw server
This mode of operation is referred to as "inetd mode" and causes bootpd (or bootpgw) to be started only when a boot request arrives. If it
does not receive another packet within fifteen minutes of the last one it received, it will exit to conserve system resources. The -t
option controls this timeout (see OPTIONS).
It is also possible to run bootpd (or bootpgw) in "standalone mode" (without inetd) by simply invoking it from a shell like any other regu-
lar command. Standalone mode is particularly useful when bootpd is used with a large configuration database, where the start up delay
might otherwise prevent timely response to client requests. (Automatic start up in standalone mode can be done by invoking bootpd from
within /etc/rc.local, for example.) Standalone mode is less useful for bootpgw which has very little start up delay because it does not
read a configuration file.
Either program automatically detects whether it was invoked from inetd or from a shell and automatically selects the appropriate mode. The
-s or -i option may be used to force standalone or inetd mode respectively (see OPTIONS).
Specifies the timeout value (in minutes) that a bootpd or bootpgw process will wait for a BOOTP packet before exiting. If no pack-
ets are received for timeout minutes, then the program will exit. A timeout value of zero means "run forever". In standalone mode,
this option is forced to zero.
Sets the debug-level variable that controls the amount of debugging messages generated. For example, -d4 or -d 4 will set the
debugging level to 4. For compatibility with older versions of bootpd, omitting the numeric parameter (i.e. just -d) will simply
increment the debug level by one.
Sets the current directory used by bootpd while checking the existence and size of client boot files. This is useful when client
boot files are specified as relative pathnames, and bootpd needs to use the same current directory as the TFTP server (typically
/tftpboot). This option is not recognized by bootpgw.
-i Force inetd mode. This option is obsolete, but remains for compatibility with older versions of bootpd.
-s Force standalone mode. This option is obsolete, but remains for compatibility with older versions of bootpd.
Specifies the name of the configuration file from which bootpd loads its database of known clients and client options (bootpd only).
Specifies the name of the file that bootpd will dump its internal database into when it receives a SIGUSR1 signal (bootpd only).
This option is only recognized if bootpd was compiled with the -DDEBUG flag.
server Specifies the name of a BOOTP server to which bootpgw will forward all BOOTREQUEST packets it receives (bootpgw only).
Both bootpd and bootpgw operate similarly in that both listen for any packets sent to the bootps port, and both simply forward any BOOTRE-
PLY packets. They differ in their handling of BOOTREQUEST packets.
When bootpgw is started, it determines the address of a BOOTP server whose name is provided as a command line parameter. When bootpgw
receives a BOOTREQUEST packet, it sets the "gateway address" and "hop count" fields in the packet and forwards the packet to the BOOTP
server at the address determined earlier. Requests are forwarded only if they indicate that the client has been waiting for at least three
When bootpd is started it reads a configuration file, (normally /etc/bootptab) that initializes the internal database of known clients and
client options. This internal database is reloaded from the configuration file when bootpd receives a hangup signal (SIGHUP) or when it
discovers that the configuration file has changed.
When bootpd receives a BOOTREQUEST packet, it looks for a database entry matching the client request. If the client is known, bootpd com-
poses a BOOTREPLY packet using the database entry found above, and sends the reply to the client (possibly using a gateway). If the client
is unknown, the request is discarded (with a notice if debug 0).
If bootpd is compiled with the -DDEBUG option, receipt of a SIGUSR1 signal causes it to dump its internal database to the file
/etc/bootpd.dump or the dumpfile specified as a command line parameter.
During initialization, both programs determine the UDP port numbers to be used by calling getservbyname (which normally uses /etc/ser-
vices). Two service names (and port numbers) are used:
bootps - BOOTP Server listening port
bootpc - BOOTP Client destination port
If the port numbers cannot be determined using getservbyname then the values default to bootps=67 and bootpc=68.
/etc/bootptab Database file read by bootpd.
/etc/bootpd.dump Debugging dump file created by bootpd.
/etc/services Internet service numbers.
/tftpboot Current directory typically used by the TFTP server and bootpd.
Individual host entries must not exceed 1024 characters.
This distribution is currently maintained by Walter L. Wimer email@example.com.
The original BOOTP server was created by Bill Croft at Stanford University in January 1986.
The current version of bootpd is primarily the work of David Kovar, Drew D. Perkins, and Walter L. Wimer, at Carnegie Mellon University.
Enhancements and bug-fixes have been contributed by:
(in alphabetical order)
Danny Backx firstname.lastname@example.org
John Brezak email@example.com
Frank da Cruz firstname.lastname@example.org
David R. Linn email@example.com
Jim McKim firstname.lastname@example.org
Gordon W. Ross email@example.com
Jason Zions firstname.lastname@example.org
bootptab(5), inetd(8), tftpd(8)
DARPA Internet Request For Comments:
RFC951 Bootstrap Protocol
RFC1532 Clarifications and Extensions for the Bootstrap Protocol
RFC1533 DHCP Options and BOOTP Vendor Extensions
Carnegie Mellon University November 06, 1993 BOOTPD(8)