a48f11afcf
My attempt to correct the sender/receiver behavior was incorrect. The source port of the sender for forwarded datagrams is filtered with -a, and my change in r314585 didn't clarify that point at all. Wording is based on suggestion by hrs. MFC after: 28 days X-MFC with: r314563, r314585 Reported by: hrs In collaboration with: hrs, rgrimes Sponsored by: Dell EMC Isilon
459 lines
11 KiB
Groff
459 lines
11 KiB
Groff
.\" Copyright (c) 1983, 1986, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)syslogd.8 8.1 (Berkeley) 6/6/93
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.\" $FreeBSD$
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.\"
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.Dd March 3, 2017
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.Dt SYSLOGD 8
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.Os
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.Sh NAME
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.Nm syslogd
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.Nd log systems messages
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.Sh SYNOPSIS
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.Nm
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.Op Fl 468ACcdFkNnosTuv
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.Op Fl a Ar allowed_peer
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.Op Fl b Ar bind_address
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.Op Fl f Ar config_file
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.Op Fl l Oo Ar mode Ns \&: Oc Ns Ar path
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.Op Fl m Ar mark_interval
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.Op Fl P Ar pid_file
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.Op Fl p Ar log_socket
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.Op Fl S Ar logpriv_socket
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.Sh DESCRIPTION
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The
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.Nm
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utility reads and logs messages to the system console,
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log files,
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other
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machines and/or users as specified by its configuration file.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl 4
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Force
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.Nm
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to use IPv4 addresses only.
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.It Fl 6
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Force
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.Nm
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to use IPv6 addresses only.
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.It Fl 8
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Tells
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.Nm
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not to interfere with 8-bit data.
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Normally
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.Nm
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will replace C1 control characters
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.Pq ISO 8859 and Unicode characters
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with their
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.Dq M- Ns Em x
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equivalent.
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Note, this option does not change the way
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.Nm
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alters control characters
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.Pq see Xr iscntrl 3 .
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They will always be replaced with their
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.Dq ^ Ns Em x
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equivalent.
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.It Fl A
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Ordinarily,
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.Nm
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tries to send the message to only one address
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even if the host has more than one A or AAAA record.
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If this option is specified,
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.Nm
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tries to send the message to all addresses.
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.It Fl a Ar allowed_peer
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Allow
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.Ar allowed_peer
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to log to this
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.Nm
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using UDP datagrams.
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Multiple
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.Fl a
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options may be specified.
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.Pp
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The
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.Ar allowed_peer
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option may be any of the following:
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.Bl -tag -width "ipaddr[/prefixlen][:service]XX"
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.It Xo
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.Sm off
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.Ar ipaddr
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.Op / Ar masklen
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.Op \&: Ar service
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.Pp
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.Ar ipaddr
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.Op / Ar prefixlen
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.Op \&: Ar service
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.Sm on
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.Xc
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Accept datagrams from
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.Ar ipaddr ,
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.Ar ipaddr
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can be specified as an IPv4 address or as an IPv6
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address enclosed with
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.Ql \&[
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and
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.Ql \&] .
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If specified,
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.Ar service
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is the name or number of an UDP service (see
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.Xr services 5 )
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the source packet must belong to.
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A
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.Ar service
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of
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.Ql \&*
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accepts UDP packets from any source port.
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The default
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.Ar service
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is
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.Ql syslog .
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If
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.Ar ipaddr
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is IPv4 address, a missing
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.Ar masklen
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will be substituted by the historic class A or class B netmasks if
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.Ar ipaddr
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belongs into the address range of class A or B,
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respectively,
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or by 24 otherwise.
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If
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.Ar ipaddr
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is IPv6 address,
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a missing
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.Ar masklen
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will be substituted by 128.
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.It Xo
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.Sm off
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.Ar domainname Op \&: Ar service
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.Sm on
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.Xc
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Accept datagrams where the reverse address lookup yields
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.Ar domainname
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for the sender address.
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The meaning of
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.Ar service
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is as explained above.
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.Ar domainname
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can contain special characters of a shell-style pattern such as
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.Ql Li \&* .
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.El
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.Pp
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The
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.Fl a
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options are ignored if the
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.Fl s
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option is also specified.
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.It Xo
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.Fl b
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.Sm off
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.Ar bind_address Op \&: Ar service
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.Sm on
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.Xc
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.It Xo
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.Fl b
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.Sm off
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.Li \&: Ar service
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.Sm on
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.Xc
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Bind to a specific address and/or port.
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The address can be specified as a hostname,
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and the port as a service name.
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If an IPv6 address is specified, it should be enclosed with
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.Ql \&[
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and
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.Ql \&] .
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The default
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.Ar service
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is
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.Ql syslog .
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This option can be specified multiple times to bind to
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multiple addresses and/or ports.
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.It Fl C
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Create log files that do not exist
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.Pq permission is set to Ql Li 0600 .
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.It Fl c
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Disable the compression of repeated instances of the same line
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into a single line of the form
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.Dq Li "last message repeated N times"
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when the output is a pipe to another program.
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If specified twice,
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disable this compression in all cases.
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.It Fl d
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Put
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.Nm
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into debugging mode.
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This is probably only of use to developers working on
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.Nm .
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.It Fl f Ar config_file
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Specify the pathname of an alternate configuration file;
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the default is
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.Pa /etc/syslog.conf .
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.It Fl F
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Run
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.Nm
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in the foreground,
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rather than going into daemon mode.
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This is useful if some other process uses
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.Xr fork 2
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and
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.Xr exec 3
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to run
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.Nm ,
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and wants to monitor when and how it exits.
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.It Fl k
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Disable the translation of
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messages received with facility
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.Dq kern
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to facility
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.Dq user .
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Usually the
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.Dq kern
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facility is reserved for messages read directly from
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.Pa /dev/klog .
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.It Fl m Ar mark_interval
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Select the number of minutes between
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.Dq mark
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messages;
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the default is 20 minutes.
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.It Fl N
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Disable binding on UDP sockets.
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RFC 3164 recommends that outgoing
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.Nm
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messages should originate from the privileged port,
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this option
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.Em disables
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the recommended behavior.
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This option inherits
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.Fl s .
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.It Fl n
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Disable DNS query for every request.
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.It Fl o
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Prefix kernel messages with the full kernel boot file as determined by
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.Xr getbootfile 3 .
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Without this, the kernel message prefix is always
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.Dq Li kernel: .
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.It Fl p Ar log_socket
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Specify the pathname of an alternate log socket to be used instead;
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the default is
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.Pa /var/run/log .
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When a single
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.Fl p
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option is specified,
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the default pathname is replaced with the specified one.
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When two or more
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.Fl p
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options are specified,
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the remaining pathnames are treated as additional log sockets.
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.It Fl P Ar pid_file
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Specify an alternative file in which to store the process ID.
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The default is
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.Pa /var/run/syslog.pid .
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.It Fl S Ar logpriv_socket
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Specify the pathname of an alternate log socket for privileged
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applications to be used instead;
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the default is
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.Pa /var/run/logpriv .
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When a single
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.Fl S
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option is specified,
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the default pathname is replaced with the specified one.
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When two or more
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.Fl S
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options are specified,
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the remaining pathnames are treated as additional log sockets.
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.It Fl l Oo Ar mode Ns \&: Oc Ns Ar path
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Specify a location where
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.Nm
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should place an additional log socket.
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The primary use for this is to place additional log sockets in
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.Pa /var/run/log
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of various chroot filespaces.
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File permissions for socket can be specified in octal representation in
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.Ar mode ,
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delimited with a colon.
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The socket location must be specified as an absolute pathname in
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.Ar path .
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.It Fl s
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Operate in secure mode.
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Do not log messages from remote machines.
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If specified twice,
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no network socket will be opened at all,
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which also disables logging to remote machines.
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.It Fl T
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Always use the local time and date for messages received from the network,
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instead of the timestamp field supplied in the message by the remote host.
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This is useful if some of the originating hosts cannot keep time properly
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or are unable to generate a correct timestamp.
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.It Fl u
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Unique priority logging.
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Only log messages at the specified priority.
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Without this option,
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messages at the stated priority or higher are logged.
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This option changes the default comparison from
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.Dq =>
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to
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.Dq = .
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.It Fl v
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Verbose logging.
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If specified once,
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the numeric facility and priority are
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logged with each locally-written message.
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If specified more than once,
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the names of the facility and priority are logged with each locally-written
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message.
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.El
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.Pp
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The
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.Nm
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utility reads its configuration file when it starts up and whenever it
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receives a hangup signal.
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For information on the format of the configuration file,
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see
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.Xr syslog.conf 5 .
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.Pp
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The
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.Nm
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utility reads messages from the
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.Ux
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domain sockets
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.Pa /var/run/log
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and
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.Pa /var/run/logpriv ,
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from an Internet domain socket specified in
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.Pa /etc/services ,
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and from the special device
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.Pa /dev/klog
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.Pq to read kernel messages .
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.Pp
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The
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.Nm
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utility creates its process ID file,
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by default
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.Pa /var/run/syslog.pid ,
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and stores its process
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ID there.
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This can be used to kill or reconfigure
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.Nm .
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.Pp
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The message sent to
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.Nm
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should consist of a single line.
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The message can contain a priority code,
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which should be a preceding
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decimal number in angle braces,
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for example,
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.Sq Aq 5 .
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This priority code should map into the priorities defined in the
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include file
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.In sys/syslog.h .
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.Pp
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For security reasons,
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.Nm
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will not append to log files that do not exist
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.Po unless Fl C
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option is specified
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.Pc ;
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therefore, they must be created manually before running
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.Nm .
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.Pp
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The date and time are taken from the received message.
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If the format of the timestamp field is incorrect,
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time obtained from the local host is used instead.
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This can be overridden by the
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.Fl T
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flag.
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.Sh FILES
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.Bl -tag -width /var/run/syslog.pid -compact
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.It Pa /etc/syslog.conf
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configuration file
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.It Pa /var/run/syslog.pid
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default process ID file
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.It Pa /var/run/log
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name of the
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.Ux
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domain datagram log socket
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.It Pa /var/run/logpriv
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.Ux
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socket for privileged applications
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.It Pa /dev/klog
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kernel log device
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.El
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.Sh SEE ALSO
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.Xr logger 1 ,
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.Xr syslog 3 ,
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.Xr services 5 ,
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.Xr syslog.conf 5 ,
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.Xr newsyslog 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.3 .
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.Pp
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The
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.Fl a ,
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.Fl s ,
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.Fl u ,
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and
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.Fl v
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options are
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.Fx 2.2
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extensions.
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.Sh BUGS
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The ability to log messages received in UDP packets is equivalent to
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an unauthenticated remote disk-filling service,
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and should probably be disabled by default.
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Some sort of
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.No inter- Ns Nm syslogd
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authentication mechanism ought to be worked out.
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To prevent the worst abuse,
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use of the
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.Fl a
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option is therefore highly recommended.
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.Pp
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The
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.Fl a
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matching algorithm does not pretend to be very efficient;
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use of numeric IP addresses is faster than domain name comparison.
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Since the allowed peer list is being walked linearly,
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peer groups where frequent messages are being anticipated
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from should be put early into the
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.Fl a
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list.
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.Pp
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The log socket was moved from
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.Pa /dev
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to ease the use of a read-only root file system.
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This may confuse
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some old binaries so that a symbolic link might be used for a
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transitional period.
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