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32 .\" @(#)syslogd.8 8.1 (Berkeley) 6/6/93
33 .\" $FreeBSD: src/usr.sbin/syslogd/syslogd.8,v 1.51 2004/07/02 23:12:57 ru Exp $
34 .\" $DragonFly: src/usr.sbin/syslogd/syslogd.8,v 1.5 2006/05/26 19:39:41 swildner Exp $
35 .\"
36 .Dd November 24, 2001
37 .Dt SYSLOGD 8
38 .Os
39 .Sh NAME
40 .Nm syslogd
41 .Nd log systems messages
42 .Sh SYNOPSIS
43 .Nm
44 .Op Fl 46Acdknosuv
45 .Op Fl a Ar allowed_peer
46 .Op Fl b Ar bind_address
47 .Op Fl f Ar config_file
48 .Op Fl l Ar path
49 .Op Fl m Ar mark_interval
50 .Op Fl P Ar pid_file
51 .Op Fl p Ar log_socket
52 .Sh DESCRIPTION
53 The
54 .Nm
55 utility reads and logs messages to the system console, log files, other
56 machines and/or users as specified by its configuration file.
57 .Pp
58 The options are as follows:
59 .Bl -tag -width indent
60 .It Fl 4
61 Force
62 .Nm
63 to use IPv4 addresses only.
64 .It Fl 6
65 Force
66 .Nm
67 to use IPv6 addresses only.
68 .It Fl A
69 Ordinarily,
70 .Nm
71 tries to send the message to only one address
72 even if the host has more than one A or AAAA record.
73 If this option is specified,
74 .Nm
75 tries to send the message to all addresses.
76 .It Fl a Ar allowed_peer
77 Allow
78 .Ar allowed_peer
79 to log to this
80 .Nm
81 using UDP datagrams.
82 Multiple
83 .Fl a
84 options may be specified.
85 .Pp
86 .Ar Allowed_peer
87 can be any of the following:
88 .Bl -tag -width "ipaddr/masklen[:service]XX"
89 .It Xo
90 .Sm off
91 .Ar ipaddr
92 .No / Ar masklen
93 .Op : Ar service
94 .Sm on
95 .Xc
96 Accept datagrams from
97 .Ar ipaddr
98 (in the usual dotted quad notation) with
99 .Ar masklen
100 bits being taken into account when doing the address comparison.
101 .Ar ipaddr
102 can be also IPv6 address by enclosing the address with
103 .Ql \&[
104 and
105 .Ql \&] .
106 If specified,
107 .Ar service
108 is the name or number of an UDP service (see
109 .Xr services 5 )
110 the source packet must belong to.
111 A
112 .Ar service
113 of
114 .Ql \&*
115 allows packets being sent from any UDP port.
116 The default
117 .Ar service
118 is
119 .Ql syslog .
120 If
121 .Ar ipaddr
122 is IPv4 address, a missing
123 .Ar masklen
124 will be substituted by the historic class A or class B netmasks if
125 .Ar ipaddr
126 belongs into the address range of class A or B, respectively, or
127 by 24 otherwise.
128 If
129 .Ar ipaddr
130 is IPv6 address, a missing
131 .Ar masklen
132 will be substituted by 128.
133 .It Xo
134 .Sm off
135 .Ar domainname Op : Ar service
136 .Sm on
137 .Xc
138 Accept datagrams where the reverse address lookup yields
139 .Ar domainname
140 for the sender address.
141 The meaning of
142 .Ar service
143 is as explained above.
144 .It Xo
145 .Sm off
146 .No * Ar domainname Op : Ar service
147 .Sm on
148 .Xc
149 Same as before, except that any source host whose name
150 .Em ends
151 in
152 .Ar domainname
153 will get permission.
154 .El
155 .Pp
156 The
157 .Fl a
158 options are ignored if the
159 .Fl s
160 option is also specified.
161 .It Fl b Ar bind_address
162 Specify one specific IP address or hostname to bind to.
163 If a hostname is specified,
164 the IPv4 or IPv6 address which corresponds to it is used.
165 .It Fl c
166 Disable the compression of repeated instances of the same line
167 into a single line of the form
168 .Dq Li "last message repeated N times"
169 when the output is a pipe to another program.
170 If specified twice, disable this compression in all cases.
171 .It Fl d
172 Put
173 .Nm
174 into debugging mode.
175 This is probably only of use to developers working on
176 .Nm .
177 .It Fl f
178 Specify the pathname of an alternate configuration file;
179 the default is
180 .Pa /etc/syslog.conf .
181 .It Fl k
182 Disable the translation of
183 messages received with facility
184 .Dq kern
185 to facility
186 .Dq user .
187 Usually the
188 .Dq kern
189 facility is reserved for messages read directly from
190 .Pa /dev/klog .
191 .It Fl m
192 Select the number of minutes between
193 .Dq mark
194 messages; the default is 20 minutes.
195 .It Fl n
196 Disable dns query for every request.
197 .It Fl o
198 Prefix kernel messages with the full kernel boot file as determined by
199 .Xr getbootfile 3 .
200 Without this, the kernel message prefix is always
201 .Dq Li kernel: .
202 .It Fl p
203 Specify the pathname of an alternate log socket to be used instead;
204 the default is
205 .Pa /var/run/log .
206 .It Fl P
207 Specify an alternative file in which to store the process ID.
208 The default is
209 .Pa /var/run/syslog.pid .
210 .It Fl l
211 Specify a location where
212 .Nm
213 should place an additional log socket.
214 Up to 19 additional logging sockets can be specified.
215 The primary use for this is to place additional log sockets in
216 .Pa /var/run/log
217 of various chroot filespaces.
218 .It Fl s
219 Operate in secure mode.
220 Do not log messages from remote machines.
221 If
222 specified twice, no network socket will be opened at all, which also
223 disables logging to remote machines.
224 .It Fl u
225 Unique priority logging.
226 Only log messages at the specified priority.
227 Without this option, messages at the stated priority or higher are logged.
228 This option changes the default comparison from
229 .Dq =>
230 to
231 .Dq = .
232 .It Fl v
233 Verbose logging.
234 If specified once, the numeric facility and priority are
235 logged with each locally-written message.
236 If specified more than once,
237 the names of the facility and priority are logged with each locally-written
238 message.
239 .El
240 .Pp
241 The
242 .Nm
243 utility reads its configuration file when it starts up and whenever it
244 receives a hangup signal.
245 For information on the format of the configuration file,
246 see
247 .Xr syslog.conf 5 .
248 .Pp
249 The
250 .Nm
251 utility reads messages from the
252 .Ux
253 domain socket
254 .Pa /var/run/log ,
255 from an Internet domain socket specified in
256 .Pa /etc/services ,
257 and from the special device
258 .Pa /dev/klog
259 (to read kernel messages).
260 .Pp
261 The
262 .Nm
263 utility creates its process ID file,
264 by default
265 .Pa /var/run/syslog.pid ,
266 and stores its process
267 ID there.
268 This can be used to kill or reconfigure
269 .Nm .
270 .Pp
271 The message sent to
272 .Nm
273 should consist of a single line.
274 The message can contain a priority code, which should be a preceding
275 decimal number in angle braces, for example,
276 .Sq Aq 5 .
277 This priority code should map into the priorities defined in the
278 include file
279 .In sys/syslog.h .
280 .Pp
281 For security reasons,
282 .Nm
283 will not append to log files that do not exist;
284 therefore, they must be created manually before running
285 .Nm .
286 .Sh FILES
287 .Bl -tag -width /var/run/syslog.pid -compact
288 .It Pa /etc/syslog.conf
289 configuration file
290 .It Pa /var/run/syslog.pid
291 default process ID file
292 .It Pa /var/run/log
293 name of the
294 .Ux
295 domain datagram log socket
296 .It Pa /dev/klog
297 kernel log device
298 .El
299 .Sh SEE ALSO
300 .Xr logger 1 ,
301 .Xr syslog 3 ,
302 .Xr services 5 ,
303 .Xr syslog.conf 5
304 .Sh HISTORY
305 The
306 .Nm
307 utility appeared in
308 .Bx 4.3 .
309 .Pp
310 The
311 .Fl a ,
312 .Fl s ,
313 .Fl u ,
314 and
315 .Fl v
316 options are
317 .Fx 2.2
318 extensions.
319 .Sh BUGS
320 The ability to log messages received in UDP packets is equivalent to
321 an unauthenticated remote disk-filling service, and should probably be
322 disabled by default.
323 Some sort of
324 .No inter- Ns Nm syslogd
325 authentication mechanism ought to be worked out.
326 To prevent the worst
327 abuse, use of the
328 .Fl a
329 option is therefore highly recommended.
330 .Pp
331 The
332 .Fl a
333 matching algorithm doesn't pretend to be very efficient; use of numeric
334 IP addresses is faster than domain name comparison.
335 Since the allowed
336 peer list is being walked linearly, peer groups where frequent messages
337 are being anticipated from should be put early into the
338 .Fl a
339 list.
340 .Pp
341 The log socket was moved from
342 .Pa /dev
343 to ease the use of a read-only root file system.
344 This may confuse
345 some old binaries so that a symbolic link might be used for a
346 transitional period.