usr.sbin/syslogd/syslogd.8

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.\"     from: @(#)syslogd.8	8.1 (Berkeley) 6/6/93
.\"
.Dd November 4, 2018
.Dt SYSLOGD 8
.Os
.Sh NAME
.Nm syslogd
.Nd log systems messages
.Sh SYNOPSIS
.Nm
.Op Fl dnrSsTUvX
.Op Fl B Ar buffer_length
.Op Fl b Ar bind_address
.Op Fl f Ar config_file
.Op Fl g Ar group
.Op Fl m Ar mark_interval
.Op Fl o Ar output_format
.Op Fl P Ar file_list
.Oo
.Fl p Ar log_socket
.Op Fl p Ar log_socket2 ...
.Oc
.Op Fl t Ar chroot_dir
.Op Fl u Ar user
.Sh DESCRIPTION
.Nm
reads and logs messages to the system console, log files, other
machines and/or users as specified by its configuration file.
The options are as follows:
.Bl -tag -width 15n
.It Fl B Ar buffer_length
Sets the receiving buffer length.
The default is 16384 bytes.
If syslogd reports buffer overflow, this needs increasing.
If you don't care about it being reported, see the
.Fl X
option.
.It Fl b Ar bind_address
Specify one specific IP address or hostname to bind to.
If a hostname is specified, the IPv4 or IPv6 address
which corresponds to it is used.
.It Fl d
Enable debugging to the standard output,
and do not disassociate from the controlling terminal.
.It Fl f Ar config_file
Specify the pathname of an alternative configuration file;
the default is
.Pa /etc/syslog.conf .
.It Fl g Ar group
Set GID to
.Ar group
after the sockets and log files have been opened.
.It Fl m Ar mark_interval
Select the number of minutes between ``mark'' messages;
the default is 20 minutes.
.It Fl n
Do not perform hostname lookups; report only numeric addresses.
.It Fl o Ar output_format
Select output message format.
.Bl -hang
.It Em bsd , rfc3164
traditional BSD Syslog format (default)
.It Em syslog , rfc5424
new syslog-protocol format
.El
.It Fl P
Specify the pathname of a file containing a list of sockets to be
created.
The format of the file is simply one socket per line.
.It Fl p Ar log_socket
Specify the pathname of a log socket.
Multiple
.Fl p
options create multiple log sockets.
If no
.Fl p
arguments are given, the default socket of
.Pa /var/run/log
is used.
.It Fl r
Disable the compression of repeated instances of the same line
into a single line of the form
.Dq last message repeated N times .
.It Fl S
Sync kernel messages to disk immediately.
.It Fl s
Select
.Dq secure
mode, in which
.Nm
does not listen on a UDP socket but only communicates over a
.Ux
domain socket.
This is valuable when the machine on
which
.Nm
runs is subject to attack over the network and it is desired
that the machine be protected from attempts to remotely fill logs
and similar attacks.
.It Fl T
Always use the local time and date for messages received from the
network, instead of the timestamp field supplied in the message
by the remote host.
This is useful if some of the originating hosts can't keep time
properly or are unable to generate a correct timestamp.
.It Fl t Ar chroot_dir
.Xr chroot 2
to
.Ar chroot_dir
after the sockets and log files have been opened.
.It Fl U
Unique priority logging.
Only log messages at the priority specified by the selector in the
configuration file.
Without this option, messages at the specified priority or higher are
logged.
This option changes the default priority comparison from
.Sq >=
to
.Sq = .
.It Fl u Ar user
Set UID to
.Ar user
after the sockets and log files have been opened.
.It Fl v
Verbose logging.
If specified once, the numeric facility and priority are logged with
each locally-written message.
If specified more than once, the names of the facility and priority are
logged with each locally-written message.
.It Fl X
Disable logging of buffer overflow.
.El
.Pp
.Nm
reads its configuration file when it starts up and whenever it
receives a hangup signal.
For information on the format of the configuration file,
see
.Xr syslog.conf 5 .
.Pp
.Nm
reads messages from the
.Ux
domain socket
.Pa /var/run/log ,
from an Internet domain socket specified in
.Pa /etc/services ,
and from the special device
.Pa /dev/klog
(to read kernel messages).
.Pp
.Nm
creates the file
.Pa /var/run/syslogd.pid ,
and stores its process
id there.
This can be used to kill or reconfigure
.Nm .
.Pp
By using multiple
.Fl p
options, one can set up many chroot environments by passing the pathname
to the log socket
.Pa ( /var/run/log )
in each chroot area to
.Nm .
For example:
.Dl syslogd -p /var/run/log -p /web/var/run/log -p /ftp/var/run/log
.Pp
Note: the normal log socket must now also be passed to
.Nm .
.Pp
The logged message includes the date, time, and hostname (or pathname of
the log socket).
Commonly, the program name and the process id is included.
.Pp
The date and time are taken from the received message.
If the format of the timestamp field is incorrect, time obtained from
the local host is used instead.
This can be overridden by the
.Fl T
flag.
.Pp
Accesses from UDP socket can be filtered by libwrap configuration files, like
.Pa /etc/hosts.deny .
Specify
.Dq Li syslogd
in
.Ar daemon_list
portion of the configuration files.
Refer to
.Xr hosts_access 5
for details.
.Ss SYSLOG PROTOCOL NOTES
.Nm
accepts messages in traditional BSD Syslog or in newer Syslog Protocol
format.
See RFC 3164 (BSD Syslog) and RFC 5424 (Syslog Protocol) for detailed
description of the message format.
Messages from the local kernel that are not tagged with a priority code
receive the default facility
.Dv LOG_KERN
and priority
.Dv LOG_NOTICE .
All other untagged messages receive the default facility
.Dv LOG_USER
and priority
.Dv LOG_NOTICE .
.Sh FILES
.Bl -tag -width /var/run/syslogd.pid -compact
.It Pa /etc/syslog.conf
The configuration file.
.It Pa /var/run/syslogd.pid
The process id of current
.Nm .
.It Pa /var/run/log
Name of the
.Ux
domain datagram log socket.
.It Pa /dev/klog
The kernel log device.
.El
.Sh SEE ALSO
.Xr logger 1 ,
.Xr syslog 3 ,
.Xr services 5 ,
.Xr syslog.conf 5 ,
.Xr newsyslog 8
.Rs
.%R RFC
.%N 3164
.%D August 2001
.%T The BSD syslog Protocol
.Re
.Rs
.%R RFC
.%N 5424
.%D March 2009
.%T The Syslog Protocol
.Re
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
Support for multiple log sockets appeared in
.Nx 1.4 .
libwrap support appeared in
.Nx 1.6 .
Support for RFC 5424, TLS encryption and authentication, signed messages
appeared in
.Nx 6.0 .