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28 .\" @(#)syslogd.8 8.1 (Berkeley) 6/6/93
29 .\" $FreeBSD: head/usr.sbin/syslogd/syslogd.8 236509 2012-06-03 11:29:48Z joel $
30 .\"
31 .Dd May 13, 2008
32 .Dt SYSLOGD 8
33 .Os
34 .Sh NAME
35 .Nm syslogd
36 .Nd log systems messages
37 .Sh SYNOPSIS
38 .Nm
39 .Op Fl 468ACcdkNnosTuv
40 .Op Fl a Ar allowed_peer
41 .Op Fl b Ar bind_address
42 .Op Fl f Ar config_file
43 .Op Fl l Oo Ar mode : Oc Ns Ar path
44 .Op Fl m Ar mark_interval
45 .Op Fl P Ar pid_file
46 .Op Fl p Ar log_socket
47 .Sh DESCRIPTION
48 The
49 .Nm
50 utility reads and logs messages to the system console, log files, other
51 machines and/or users as specified by its configuration file.
52 .Pp
53 The options are as follows:
54 .Bl -tag -width indent
55 .It Fl 4
56 Force
57 .Nm
58 to use IPv4 addresses only.
59 .It Fl 6
60 Force
61 .Nm
62 to use IPv6 addresses only.
63 .It Fl 8
64 Tells
65 .Nm
66 not to interfere with 8-bit data. Normally
67 .Nm
68 will replace C1 control characters
69 .Pq ISO 8859 and Unicode characters
70 with their
71 .Dq M- Ns Em x
72 equivalent.
73 Note, this option does not change the way
74 .Nm
75 alters control characters
76 .Pq see Xr iscntrl 3 .
77 They will always be replaced with their
78 .Dq ^ Ns Em x
79 equivalent.
80 .It Fl A
81 Ordinarily,
82 .Nm
83 tries to send the message to only one address
84 even if the host has more than one A or AAAA record.
85 If this option is specified,
86 .Nm
87 tries to send the message to all addresses.
88 .It Fl a Ar allowed_peer
89 Allow
90 .Ar allowed_peer
91 to log to this
92 .Nm
93 using UDP datagrams.
94 Multiple
95 .Fl a
96 options may be specified.
97 .Pp
98 The
99 .Ar allowed_peer
100 option may be any of the following:
101 .Bl -tag -width "ipaddr/masklen[:service]XX"
102 .It Xo
103 .Sm off
104 .Ar ipaddr
105 .No / Ar masklen
106 .Op : Ar service
107 .Sm on
108 .Xc
109 Accept datagrams from
110 .Ar ipaddr
111 (in the usual dotted quad notation) with
112 .Ar masklen
113 bits being taken into account when doing the address comparison.
114 .Ar ipaddr
115 can be also IPv6 address by enclosing the address with
116 .Ql \&[
117 and
118 .Ql \&] .
119 If specified,
120 .Ar service
121 is the name or number of an UDP service (see
122 .Xr services 5 )
123 the source packet must belong to.
124 A
125 .Ar service
126 of
127 .Ql \&*
128 allows packets being sent from any UDP port.
129 The default
130 .Ar service
131 is
132 .Ql syslog .
133 If
134 .Ar ipaddr
135 is IPv4 address, a missing
136 .Ar masklen
137 will be substituted by the historic class A or class B netmasks if
138 .Ar ipaddr
139 belongs into the address range of class A or B, respectively, or
140 by 24 otherwise.
141 If
142 .Ar ipaddr
143 is IPv6 address, a missing
144 .Ar masklen
145 will be substituted by 128.
146 .It Xo
147 .Sm off
148 .Ar domainname Op : Ar service
149 .Sm on
150 .Xc
151 Accept datagrams where the reverse address lookup yields
152 .Ar domainname
153 for the sender address.
154 The meaning of
155 .Ar service
156 is as explained above.
157 .It Xo
158 .Sm off
159 .No * Ar domainname Op : Ar service
160 .Sm on
161 .Xc
162 Same as before, except that any source host whose name
163 .Em ends
164 in
165 .Ar domainname
166 will get permission.
167 .El
168 .Pp
169 The
170 .Fl a
171 options are ignored if the
172 .Fl s
173 option is also specified.
174 .It Xo
175 .Fl b
176 .Sm off
177 .Ar bind_address Op : Ar service
178 .Sm on
179 .Xc
180 .It Xo
181 .Fl b
182 .Sm off
183 .Li : Ar service
184 .Sm on
185 .Xc
186 Bind to a specific address and/or port.
187 The address can be specified as a hostname,
188 and the port as a service name.
189 If an IPv6 address is specified, it should be enclosed with
190 .Ql \&[
191 and
192 .Ql \&] .
193 The default
194 .Ar service
195 is
196 .Ql syslog .
197 .It Fl C
198 Create log files that do not exist (permission is set to
199 .Li 0600 ) .
200 .It Fl c
201 Disable the compression of repeated instances of the same line
202 into a single line of the form
203 .Dq Li "last message repeated N times"
204 when the output is a pipe to another program.
205 If specified twice, disable this compression in all cases.
206 .It Fl d
207 Put
208 .Nm
209 into debugging mode.
210 This is probably only of use to developers working on
211 .Nm .
212 .It Fl f
213 Specify the pathname of an alternate configuration file;
214 the default is
215 .Pa /etc/syslog.conf .
216 .It Fl k
217 Disable the translation of
218 messages received with facility
219 .Dq kern
220 to facility
221 .Dq user .
222 Usually the
223 .Dq kern
224 facility is reserved for messages read directly from
225 .Pa /dev/klog .
226 .It Fl m
227 Select the number of minutes between
228 .Dq mark
229 messages; the default is 20 minutes.
230 .It Fl N
231 Disable binding on UDP sockets. RFC 3164 recommends that outgoing
232 syslogd messages should originate from the privileged port, this
233 option
234 .Em disables
235 the recommended behavior. This option inherits
236 .Fl s .
237 .It Fl n
238 Disable dns query for every request.
239 .It Fl o
240 Prefix kernel messages with the full kernel boot file as determined by
241 .Xr getbootfile 3 .
242 Without this, the kernel message prefix is always
243 .Dq Li kernel: .
244 .It Fl p
245 Specify the pathname of an alternate log socket to be used instead;
246 the default is
247 .Pa /var/run/log .
248 .It Fl P
249 Specify an alternative file in which to store the process ID.
250 The default is
251 .Pa /var/run/syslog.pid .
252 .It Fl S
253 Specify the pathname of an alternate log socket for privileged
254 applications to be used instead; the default is
255 .Pa /var/run/logpriv .
256 .It Fl l
257 Specify a location where
258 .Nm
259 should place an additional log socket.
260 The primary use for this is to place additional log sockets in
261 .Pa /var/run/log
262 of various chroot filespaces.
263 File permissions for socket can be specified in octal representation
264 before socket name, delimited with a colon.
265 Path to socket location must be absolute.
266 .It Fl s
267 Operate in secure mode.
268 Do not log messages from remote machines.
269 If
270 specified twice, no network socket will be opened at all, which also
271 disables logging to remote machines.
272 .It Fl T
273 Always use the local time and date for messages received from the network,
274 instead of the timestamp field supplied in the message by the remote host.
275 This is useful if some of the originating hosts can't keep time properly
276 or are unable to generate a correct timestamp.
277 .It Fl u
278 Unique priority logging.
279 Only log messages at the specified priority.
280 Without this option, messages at the stated priority or higher are logged.
281 This option changes the default comparison from
282 .Dq =>
283 to
284 .Dq = .
285 .It Fl v
286 Verbose logging.
287 If specified once, the numeric facility and priority are
288 logged with each locally-written message.
289 If specified more than once,
290 the names of the facility and priority are logged with each locally-written
291 message.
292 .El
293 .Pp
294 The
295 .Nm
296 utility reads its configuration file when it starts up and whenever it
297 receives a hangup signal.
298 For information on the format of the configuration file,
299 see
300 .Xr syslog.conf 5 .
301 .Pp
302 The
303 .Nm
304 utility reads messages from the
305 .Ux
306 domain sockets
307 .Pa /var/run/log
308 and
309 .Pa /var/run/logpriv ,
310 from an Internet domain socket specified in
311 .Pa /etc/services ,
312 and from the special device
313 .Pa /dev/klog
314 (to read kernel messages).
315 .Pp
316 The
317 .Nm
318 utility creates its process ID file,
319 by default
320 .Pa /var/run/syslog.pid ,
321 and stores its process
322 ID there.
323 This can be used to kill or reconfigure
324 .Nm .
325 .Pp
326 The message sent to
327 .Nm
328 should consist of a single line.
329 The message can contain a priority code, which should be a preceding
330 decimal number in angle braces, for example,
331 .Sq Aq 5 .
332 This priority code should map into the priorities defined in the
333 include file
334 .In sys/syslog.h .
335 .Pp
336 For security reasons,
337 .Nm
338 will not append to log files that do not exist (unless
339 .Fl C
340 option is specified);
341 therefore, they must be created manually before running
342 .Nm .
343 .Pp
344 The date and time are taken from the received message.
345 If the format of the timestamp field is incorrect,
346 time obtained from the local host is used instead.
347 This can be overridden by the
348 .Fl T
349 flag.
350 .Sh FILES
351 .Bl -tag -width /var/run/syslog.pid -compact
352 .It Pa /etc/syslog.conf
353 configuration file
354 .It Pa /var/run/syslog.pid
355 default process ID file
356 .It Pa /var/run/log
357 name of the
358 .Ux
359 domain datagram log socket
360 .It Pa /var/run/logpriv
361 .Ux
362 socket for privileged applications
363 .It Pa /dev/klog
364 kernel log device
365 .El
366 .Sh SEE ALSO
367 .Xr logger 1 ,
368 .Xr syslog 3 ,
369 .Xr services 5 ,
370 .Xr syslog.conf 5 ,
371 .Xr newsyslog 8
372 .Sh HISTORY
373 The
374 .Nm
375 utility appeared in
376 .Bx 4.3 .
377 .Pp
378 The
379 .Fl a ,
380 .Fl s ,
381 .Fl u ,
382 and
383 .Fl v
384 options are
385 .Fx 2.2
386 extensions.
387 .Sh BUGS
388 The ability to log messages received in UDP packets is equivalent to
389 an unauthenticated remote disk-filling service, and should probably be
390 disabled by default.
391 Some sort of
392 .No inter- Ns Nm syslogd
393 authentication mechanism ought to be worked out.
394 To prevent the worst
395 abuse, use of the
396 .Fl a
397 option is therefore highly recommended.
398 .Pp
399 The
400 .Fl a
401 matching algorithm does not pretend to be very efficient; use of numeric
402 IP addresses is faster than domain name comparison.
403 Since the allowed
404 peer list is being walked linearly, peer groups where frequent messages
405 are being anticipated from should be put early into the
406 .Fl a
407 list.
408 .Pp
409 The log socket was moved from
410 .Pa /dev
411 to ease the use of a read-only root file system.
412 This may confuse
413 some old binaries so that a symbolic link might be used for a
414 transitional period.