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28 .\" @(#)syslogd.8 8.1 (Berkeley) 6/6/93
29 .\" $FreeBSD: src/usr.sbin/syslogd/syslogd.8,v 1.64 2008/12/07 18:45:30 trhodes Exp $
30 .\" $DragonFly: src/usr.sbin/syslogd/syslogd.8,v 1.5 2006/05/26 19:39:41 swildner Exp $
31 .\"
32 .Dd May 13, 2008
33 .Dt SYSLOGD 8
34 .Os
35 .Sh NAME
36 .Nm syslogd
37 .Nd log systems messages
38 .Sh SYNOPSIS
39 .Nm
40 .Op Fl 468ACcdknosuv
41 .Op Fl a Ar allowed_peer
42 .Op Fl b Ar bind_address
43 .Op Fl f Ar config_file
44 .Op Fl l Oo Ar mode : Oc Ns Ar path
45 .Op Fl m Ar mark_interval
46 .Op Fl P Ar pid_file
47 .Op Fl p Ar log_socket
48 .Sh DESCRIPTION
49 The
50 .Nm
51 utility reads and logs messages to the system console, log files, other
52 machines and/or users as specified by its configuration file.
53 .Pp
54 The options are as follows:
55 .Bl -tag -width indent
56 .It Fl 4
57 Force
58 .Nm
59 to use IPv4 addresses only.
60 .It Fl 6
61 Force
62 .Nm
63 to use IPv6 addresses only.
64 .It Fl 8
65 Tells
66 .Nm
67 not to interfere with 8-bit data. Normally
68 .Nm
69 will replace C1 control characters
70 .Pq ISO 8859 and Unicode characters
71 with their
72 .Dq M- Ns Em x
73 equivalent.
74 Note, this option does not change the way
75 .Nm
76 alters control characters
77 .Pq see Xr iscntrl 3 .
78 They will always be replaced with their
79 .Dq ^ Ns Em x
80 equivalent.
81 .It Fl A
82 Ordinarily,
83 .Nm
84 tries to send the message to only one address
85 even if the host has more than one A or AAAA record.
86 If this option is specified,
87 .Nm
88 tries to send the message to all addresses.
89 .It Fl a Ar allowed_peer
90 Allow
91 .Ar allowed_peer
92 to log to this
93 .Nm
94 using UDP datagrams.
95 Multiple
96 .Fl a
97 options may be specified.
98 .Pp
99 The
100 .Ar allowed_peer
101 option may be any of the following:
102 .Bl -tag -width "ipaddr/masklen[:service]XX"
103 .It Xo
104 .Sm off
105 .Ar ipaddr
106 .No / Ar masklen
107 .Op : Ar service
108 .Sm on
109 .Xc
110 Accept datagrams from
111 .Ar ipaddr
112 (in the usual dotted quad notation) with
113 .Ar masklen
114 bits being taken into account when doing the address comparison.
115 .Ar ipaddr
116 can be also IPv6 address by enclosing the address with
117 .Ql \&[
118 and
119 .Ql \&] .
120 If specified,
121 .Ar service
122 is the name or number of an UDP service (see
123 .Xr services 5 )
124 the source packet must belong to.
125 A
126 .Ar service
127 of
128 .Ql \&*
129 allows packets being sent from any UDP port.
130 The default
131 .Ar service
132 is
133 .Ql syslog .
134 If
135 .Ar ipaddr
136 is IPv4 address, a missing
137 .Ar masklen
138 will be substituted by the historic class A or class B netmasks if
139 .Ar ipaddr
140 belongs into the address range of class A or B, respectively, or
141 by 24 otherwise.
142 If
143 .Ar ipaddr
144 is IPv6 address, a missing
145 .Ar masklen
146 will be substituted by 128.
147 .It Xo
148 .Sm off
149 .Ar domainname Op : Ar service
150 .Sm on
151 .Xc
152 Accept datagrams where the reverse address lookup yields
153 .Ar domainname
154 for the sender address.
155 The meaning of
156 .Ar service
157 is as explained above.
158 .It Xo
159 .Sm off
160 .No * Ar domainname Op : Ar service
161 .Sm on
162 .Xc
163 Same as before, except that any source host whose name
164 .Em ends
165 in
166 .Ar domainname
167 will get permission.
168 .El
169 .Pp
170 The
171 .Fl a
172 options are ignored if the
173 .Fl s
174 option is also specified.
175 .It Fl b Ar bind_address
176 Specify one specific IP address or hostname to bind to.
177 If a hostname is specified,
178 the IPv4 or IPv6 address which corresponds to it is used.
179 .It Fl C
180 Create log files that do not exist (permission is set to
181 .Li 0600 ) .
182 .It Fl c
183 Disable the compression of repeated instances of the same line
184 into a single line of the form
185 .Dq Li "last message repeated N times"
186 when the output is a pipe to another program.
187 If specified twice, disable this compression in all cases.
188 .It Fl d
189 Put
190 .Nm
191 into debugging mode.
192 This is probably only of use to developers working on
193 .Nm .
194 .It Fl f
195 Specify the pathname of an alternate configuration file;
196 the default is
197 .Pa /etc/syslog.conf .
198 .It Fl k
199 Disable the translation of
200 messages received with facility
201 .Dq kern
202 to facility
203 .Dq user .
204 Usually the
205 .Dq kern
206 facility is reserved for messages read directly from
207 .Pa /dev/klog .
208 .It Fl m
209 Select the number of minutes between
210 .Dq mark
211 messages; the default is 20 minutes.
212 .It Fl n
213 Disable dns query for every request.
214 .It Fl o
215 Prefix kernel messages with the full kernel boot file as determined by
216 .Xr getbootfile 3 .
217 Without this, the kernel message prefix is always
218 .Dq Li kernel: .
219 .It Fl p
220 Specify the pathname of an alternate log socket to be used instead;
221 the default is
222 .Pa /var/run/log .
223 .It Fl P
224 Specify an alternative file in which to store the process ID.
225 The default is
226 .Pa /var/run/syslog.pid .
227 .It Fl S
228 Specify the pathname of an alternate log socket for privileged
229 applications to be used instead; the default is
230 .Pa /var/run/logpriv .
231 .It Fl l
232 Specify a location where
233 .Nm
234 should place an additional log socket.
235 The primary use for this is to place additional log sockets in
236 .Pa /var/run/log
237 of various chroot filespaces.
238 File permissions for socket can be specified in octal representation
239 before socket name, delimited with a colon.
240 Path to socket location must be absolute.
241 .It Fl s
242 Operate in secure mode.
243 Do not log messages from remote machines.
244 If
245 specified twice, no network socket will be opened at all, which also
246 disables logging to remote machines.
247 .It Fl T
248 Always use the local time and date for messages received from the network,
249 instead of the timestamp field supplied in the message by the remote host.
250 This is useful if some of the originating hosts can't keep time properly
251 or are unable to generate a correct timestamp.
252 .It Fl u
253 Unique priority logging.
254 Only log messages at the specified priority.
255 Without this option, messages at the stated priority or higher are logged.
256 This option changes the default comparison from
257 .Dq =>
258 to
259 .Dq = .
260 .It Fl v
261 Verbose logging.
262 If specified once, the numeric facility and priority are
263 logged with each locally-written message.
264 If specified more than once,
265 the names of the facility and priority are logged with each locally-written
266 message.
267 .El
268 .Pp
269 The
270 .Nm
271 utility reads its configuration file when it starts up and whenever it
272 receives a hangup signal.
273 For information on the format of the configuration file,
274 see
275 .Xr syslog.conf 5 .
276 .Pp
277 The
278 .Nm
279 utility reads messages from the
280 .Ux
281 domain sockets
282 .Pa /var/run/log
283 and
284 .Pa /var/run/logpriv ,
285 from an Internet domain socket specified in
286 .Pa /etc/services ,
287 and from the special device
288 .Pa /dev/klog
289 (to read kernel messages).
290 .Pp
291 The
292 .Nm
293 utility creates its process ID file,
294 by default
295 .Pa /var/run/syslog.pid ,
296 and stores its process
297 ID there.
298 This can be used to kill or reconfigure
299 .Nm .
300 .Pp
301 The message sent to
302 .Nm
303 should consist of a single line.
304 The message can contain a priority code, which should be a preceding
305 decimal number in angle braces, for example,
306 .Sq Aq 5 .
307 This priority code should map into the priorities defined in the
308 include file
309 .In sys/syslog.h .
310 .Pp
311 For security reasons,
312 .Nm
313 will not append to log files that do not exist (unless
314 .Fl C
315 option is specified);
316 therefore, they must be created manually before running
317 .Nm .
318 .Pp
319 The date and time are taken from the received message.
320 If the format of the timestamp field is incorrect,
321 time obtained from the local host is used instead.
322 This can be overriden by the
323 .Fl T
324 flag.
325 .Sh FILES
326 .Bl -tag -width /var/run/syslog.pid -compact
327 .It Pa /etc/syslog.conf
328 configuration file
329 .It Pa /var/run/syslog.pid
330 default process ID file
331 .It Pa /var/run/log
332 name of the
333 .Ux
334 domain datagram log socket
335 .It Pa /var/run/logpriv
336 .Ux
337 socket for privileged applications
338 .It Pa /dev/klog
339 kernel log device
340 .El
341 .Sh SEE ALSO
342 .Xr logger 1 ,
343 .Xr syslog 3 ,
344 .Xr services 5 ,
345 .Xr syslog.conf 5 ,
346 .Xr newsyslog 8
347 .Sh HISTORY
348 The
349 .Nm
350 utility appeared in
351 .Bx 4.3 .
352 .Pp
353 The
354 .Fl a ,
355 .Fl s ,
356 .Fl u ,
357 and
358 .Fl v
359 options are
360 .Fx 2.2
361 extensions.
362 .Sh BUGS
363 The ability to log messages received in UDP packets is equivalent to
364 an unauthenticated remote disk-filling service, and should probably be
365 disabled by default.
366 Some sort of
367 .No inter- Ns Nm syslogd
368 authentication mechanism ought to be worked out.
369 To prevent the worst
370 abuse, use of the
371 .Fl a
372 option is therefore highly recommended.
373 .Pp
374 The
375 .Fl a
376 matching algorithm does not pretend to be very efficient; use of numeric
377 IP addresses is faster than domain name comparison.
378 Since the allowed
379 peer list is being walked linearly, peer groups where frequent messages
380 are being anticipated from should be put early into the
381 .Fl a
382 list.
383 .Pp
384 The log socket was moved from
385 .Pa /dev
386 to ease the use of a read-only root file system.
387 This may confuse
388 some old binaries so that a symbolic link might be used for a
389 transitional period.