xref: /freebsd/libexec/bootpd/bootpd.8 (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1.\" Copyright (c) 1988, 1989, 1991 Carnegie Mellon University
2.\"
3.\" $FreeBSD$
4.\"
5.Dd May 21, 2019
6.Dt BOOTPD 8
7.Os
8.Sh NAME
9.Nm bootpd , bootpgw
10.Nd Internet Boot Protocol server/gateway
11.Sh SYNOPSIS
12.Nm
13.Op Fl i | s
14.Op Fl c Ar chdir-path
15.Op Fl d Ar level
16.Op Fl h Ar hostname
17.Op Fl t Ar timeout
18.Oo
19.Ar bootptab
20.Op Ar dumpfile
21.Oc
22.Nm bootpgw
23.Op Fl i | s
24.Op Fl d Ar level
25.Op Fl h Ar hostname
26.Op Fl t Ar timeout
27.Ar server
28.Sh DESCRIPTION
29The
30.Nm
31utility
32implements an Internet Bootstrap Protocol (BOOTP) server as defined in
33RFC951, RFC1532, and RFC1533.
34The
35.Nm bootpgw
36utility implements a simple BOOTP gateway which can be used to forward
37requests and responses between clients on one subnet and a
38BOOTP server (i.e.\&
39.Nm )
40on another subnet.
41While either
42.Nm
43or
44.Nm bootpgw
45will forward BOOTREPLY packets, only
46.Nm bootpgw
47will forward BOOTREQUEST packets.
48.Pp
49One host on each network segment is normally configured to run either
50.Nm
51or
52.Nm bootpgw
53from
54.Xr inetd 8
55by including one of the following lines in the file
56.Pa /etc/inetd.conf :
57.Pp
58.Dl bootps dgram udp wait root /usr/libexec/bootpd bootpd /etc/bootptab
59.Dl bootps dgram udp wait root /usr/libexec/bootpgw bootpgw server
60.Pp
61This mode of operation is referred to as "inetd mode" and causes
62.Nm
63(or
64.Nm bootpgw )
65to be started only when a boot request arrives.
66If it does not
67receive another packet within fifteen minutes of the last one
68it received, it will exit to conserve system resources.
69The
70.Fl t
71option controls this timeout (see OPTIONS).
72.Pp
73It is also possible to run
74.Nm
75(or
76.Nm bootpgw )
77in "standalone mode" (without
78.Xr inetd 8 )
79by simply invoking it from a shell like any other regular command.
80Standalone mode is particularly useful when
81.Nm
82is used with a large configuration database, where the start up
83delay might otherwise prevent timely response to client requests.
84(Automatic start up in standalone mode can be done by invoking
85.Nm
86from within
87.Pa /etc/rc.local ,
88for example.)
89Standalone mode is less useful for
90.Nm bootpgw
91which
92has very little start up delay because
93it does not read a configuration file.
94.Pp
95Either program automatically detects whether it was invoked from inetd
96or from a shell and automatically selects the appropriate mode.
97The
98.Fl s
99or
100.Fl i
101option may be used to force standalone or inetd mode respectively
102(see OPTIONS).
103.Sh OPTIONS
104The following options are available:
105.Bl -tag -width indent
106.It Fl a
107Skip ARP table modifications.
108.It Fl t Ar timeout
109Specify the
110.Ar timeout
111value (in minutes) that a
112.Nm
113or
114.Nm bootpgw
115process will wait for a BOOTP packet before exiting.
116If no packets are received for
117.Ar timeout
118minutes, then the program will exit.
119A timeout value of zero means "run forever".
120In standalone mode, this option is forced to zero.
121.It Fl d Ar debug-level
122Set the
123.Ar debug-level
124variable that controls the amount of debugging messages generated.
125For example,
126.Fl d Ns 4
127or
128.Fl d
1294 will set the debugging level to 4.
130For compatibility with older versions of
131.Nm ,
132omitting the numeric parameter (i.e., just
133.Fl d )
134will simply increment the debug level by one.
135.It Fl c Ar chdir-path
136Set the current directory used by
137.Nm
138while checking the existence and size of client boot files.
139This is
140useful when client boot files are specified as relative pathnames, and
141.Nm
142needs to use the same current directory as the TFTP server
143(typically
144.Pa /tftpboot ) .
145This option is not recognized by
146.Nm bootpgw .
147.It Fl h Ar hostname
148Specify the hostname corresponding to the IP address to listen on.
149By default,
150.Nm
151listens on the IP address corresponding to the machine's hostname, as
152returned by
153.Xr gethostname 3 .
154.It Fl i
155Force inetd mode.
156This option is obsolete, but remains for
157compatibility with older versions of
158.Nm .
159.It Fl s
160Force standalone mode.
161This option is obsolete, but remains for
162compatibility with older versions of
163.Nm .
164.It Ar bootptab
165Specify the name of the configuration file from which
166.Nm
167loads its database of known clients and client options
168.No ( Nm
169only).
170.It Ar dumpfile
171Specify the name of the file that
172.Nm
173will dump its internal database into when it receives a
174SIGUSR1 signal
175.No ( Nm
176only).
177This option is only recognized if
178.Nm
179was compiled with the -DDEBUG flag.
180.It Ar server
181Specify the name of a BOOTP server to which
182.Nm bootpgw
183will forward all BOOTREQUEST packets it receives
184.Pf ( Nm bootpgw
185only).
186.El
187.Sh OPERATION
188Both
189.Nm
190and
191.Nm bootpgw
192operate similarly in that both listen for any packets sent to the
193.Em bootps
194port, and both simply forward any BOOTREPLY packets.
195They differ in their handling of BOOTREQUEST packets.
196.Pp
197When
198.Nm bootpgw
199is started, it determines the address of a BOOTP server
200whose name is provided as a command line parameter.
201When
202.Nm bootpgw
203receives a BOOTREQUEST packet, it sets the "gateway address"
204and "hop count" fields in the packet and forwards the packet
205to the BOOTP server at the address determined earlier.
206Requests are forwarded only if they indicate that
207the client has been waiting for at least three seconds.
208.Pp
209When
210.Nm
211is started it reads a configuration file, (normally
212.Pa /etc/bootptab )
213that initializes the internal database of known clients and client
214options.
215This internal database is reloaded
216from the configuration file when
217.Nm
218receives a hangup signal (SIGHUP) or when it discovers that the
219configuration file has changed.
220.Pp
221When
222.Nm
223receives a BOOTREQUEST packet, it
224.\" checks the modification time of the
225.\" configuration file and reloads the database if necessary.  Then it
226looks for a database entry matching the client request.
227If the client is known,
228.Nm
229composes a BOOTREPLY packet using the database entry found above,
230and sends the reply to the client (possibly using a gateway).
231If the client is unknown, the request is discarded
232(with a notice if debug > 0).
233.Pp
234If
235.Nm
236is compiled with the -DDEBUG option, receipt of a SIGUSR1 signal causes
237it to dump its internal database to the file
238.Pa /tmp/bootpd.dump
239or the dumpfile specified as a command line parameter.
240.Pp
241During initialization, both programs
242determine the UDP port numbers to be used by calling
243.Xr getservbyname 3
244(which normally uses
245.Pa /etc/services ) .
246Two service names (and port numbers) are used:
247.Pp
248.Dl bootps BOOTP Server listening port
249.Dl bootpc BOOTP Client destination port
250.Pp
251If the port numbers cannot be determined using
252.Xr getservbyname 3
253then the values default to bootps=67 and bootpc=68.
254.Sh FILES
255.Bl -tag -width /tmp/bootpd.dump -compact
256.It Pa /etc/bootptab
257Database file read by
258.Nm .
259.It Pa /tmp/bootpd.dump
260Debugging dump file created by
261.Nm .
262.It Pa /etc/services
263Internet service numbers.
264.It Pa /tftpboot
265Current directory typically used by the TFTP server and
266.Nm .
267.El
268.Sh "SEE ALSO"
269.Xr bootptab 5 ,
270.Xr inetd 8 ,
271.Xr tftpd 8
272.Pp
273DARPA Internet Request For Comments:
274.Bl -tag -width RFC1533 -compact
275.It RFC951
276Bootstrap Protocol
277.It RFC1532
278Clarifications and Extensions for the Bootstrap Protocol
279.It RFC1533
280DHCP Options and BOOTP Vendor Extensions
281.El
282.Sh AUTHORS
283This distribution is currently maintained by
284.An Walter L. Wimer Aq Mt walt+@cmu.edu .
285.Pp
286The original BOOTP server was created by
287.An Bill Croft
288at Stanford University in January 1986.
289.Pp
290The current version of
291.Nm
292is primarily the work of
293.An David Kovar ,
294.An Drew D. Perkins ,
295and
296.An Walter L. Wimer ,
297at Carnegie Mellon University.
298.Pp
299Enhancements and bug-fixes have been contributed by:
300.Pp
301(in alphabetical order)
302.Pp
303.An -split
304.An Danny Backx Aq Mt db@sunbim.be
305.An John Brezak Aq Mt brezak@ch.hp.com
306.An Frank da Cruz Aq Mt fdc@cc.columbia.edu
307.An David R. Linn Aq Mt drl@vuse.vanderbilt.edu
308.An Jim McKim Aq Mt mckim@lerc.nasa.gov
309.An Gordon W. Ross Aq Mt gwr@mc.com
310.An Jason Zions Aq Mt jazz@hal.com .
311.Sh BUGS
312Individual host entries must not exceed 1024 characters.
313