SYSLOGD(8) FreeBSD System Manager's Manual SYSLOGD(8)
NAME
syslogd - log systems messages
SYNOPSIS
syslogd [-468ACcdFHkNnosTuv] [-a allowed_peer] [-b bind_address]
[-f config_file] [-l [mode:]path] [-M fwd_length]
[-m mark_interval] [-O format] [-P pid_file] [-p log_socket]
[-S logpriv_socket]
DESCRIPTION
The syslogd utility 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:
-4 Force syslogd to use IPv4 addresses only.
-6 Force syslogd to use IPv6 addresses only.
-8 Tells syslogd not to interfere with 8-bit data. Normally syslogd
will replace C1 control characters (ISO 8859 and Unicode
characters) with their "M-x" equivalent. Note, this option does
not change the way syslogd alters control characters (see
iscntrl(3)). They will always be replaced with their "^x"
equivalent.
-A Ordinarily, syslogd tries to send the message to only one address
even if the host has more than one A or AAAA record. If this
option is specified, syslogd tries to send the message to all
addresses.
-a allowed_peer
Allow allowed_peer to log to this syslogd using UDP datagrams.
Multiple -a options may be specified.
The allowed_peer option may be any of the following:
ipaddr[/masklen][:service]
ipaddr[/prefixlen][:service] Accept datagrams from ipaddr,
ipaddr can be specified as an
IPv4 address or as an IPv6
address enclosed with `[' and
`]'. If specified, service is
the name or number of an UDP
service (see services(5)) the
source packet must belong to. A
service of `*' accepts UDP
packets from any source port.
The default service is `syslog'.
If ipaddr is IPv4 address, a
missing masklen will be
substituted by the historic class
A or class B netmasks if ipaddr
belongs into the address range of
class A or B, respectively, or by
24 otherwise. If ipaddr is IPv6
address, a missing masklen will
be substituted by 128.
domainname[:service] Accept datagrams where the
reverse address lookup yields
domainname for the sender
address. The meaning of service
is as explained above.
domainname can contain special
characters of a shell-style
pattern such as `*'.
The -a options are ignored if the -s option is also specified.
-b bind_address[:service]
-b :service
Bind to a specific address and/or port. The address can be
specified as a hostname, and the port as a service name. If an
IPv6 address is specified, it should be enclosed with `[' and
`]'. The default service is `syslog'. This option can be
specified multiple times to bind to multiple addresses and/or
ports.
-C Create log files that do not exist (permission is set to `0600').
-c Disable the compression of repeated instances of the same line
into a single line of the form "last message repeated N times"
when the output is a pipe to another program. If specified
twice, disable this compression in all cases.
-d Put syslogd into debugging mode. This is probably only of use to
developers working on syslogd.
-f config_file
Specify the pathname of an alternate configuration file; the
default is /etc/syslog.conf.
-F Run syslogd in the foreground, rather than going into daemon
mode. This is useful if some other process uses fork(2) and
exec(3) to run syslogd, and wants to monitor when and how it
exits.
-H When logging remote messages use hostname from the message (if
supplied) instead of using address from which the message was
received.
-k Disable the translation of messages received with facility "kern"
to facility "user". Usually the "kern" facility is reserved for
messages read directly from /dev/klog.
-M fwd_length
Set the limit on the length of forwarded messages. The minimum
is 480 octets. The maximum for RFC 3164 output format is 1024
octets. The default is 1024 octets.
-m mark_interval
Select the number of minutes between "mark" messages; the default
is 20 minutes.
-N Disable binding on UDP sockets. RFC 3164 recommends that
outgoing syslogd messages should originate from the privileged
port, this option disables the recommended behavior. This option
inherits -s.
-n Disable DNS query for every request.
-O format
Select the output format of generated log messages. The values
bsd and rfc3164 are used to generate RFC 3164 log messages. The
values syslog and rfc5424 are used to generate RFC 5424 log
messages, having RFC 3339 timestamps with microsecond precision.
The default is to generate RFC 3164 log messages.
-o Prefix kernel messages with the full kernel boot file as
determined by getbootfile(3). Without this, the kernel message
prefix is always "kernel:".
-p log_socket
Specify the pathname of an alternate log socket to be used
instead; the default is /var/run/log. When a single -p option is
specified, the default pathname is replaced with the specified
one. When two or more -p options are specified, the remaining
pathnames are treated as additional log sockets.
-P pid_file
Specify an alternative file in which to store the process ID.
The default is /var/run/syslog.pid.
-S logpriv_socket
Specify the pathname of an alternate log socket for privileged
applications to be used instead; the default is /var/run/logpriv.
When a single -S option is specified, the default pathname is
replaced with the specified one. When two or more -S options are
specified, the remaining pathnames are treated as additional log
sockets.
-l [mode:]path
Specify a location where syslogd should place an additional log
socket. The primary use for this is to place additional log
sockets in /var/run/log of various chroot filespaces. File
permissions for socket can be specified in octal representation
in mode, delimited with a colon. The socket location must be
specified as an absolute pathname in path.
-s Operate in secure mode. Do not log messages from remote
machines. If specified twice, no network socket will be opened
at all, which also disables logging to remote machines.
-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 cannot keep time properly or are unable to generate a
correct timestamp.
-u Unique priority logging. Only log messages at the specified
priority. Without this option, messages at the stated priority
or higher are logged. This option changes the default comparison
from "=>" to "=".
-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.
This option only affects the formatting of RFC 3164 messages.
Messages formatted according to RFC 5424 always include a
facility/priority number.
The syslogd utility 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 syslog.conf(5).
The syslogd utility reads messages from the UNIX domain sockets
/var/run/log and /var/run/logpriv, from an Internet domain socket
specified in /etc/services, and from the special device /dev/klog (to
read kernel messages).
The syslogd utility creates its process ID file, by default
/var/run/syslog.pid, and stores its process ID there. This can be used
to kill or reconfigure syslogd.
The message sent to syslogd should consist of a single line. The message
can contain a priority code, which should be a preceding decimal number
in angle braces, for example, `<5>'. This priority code should map into
the priorities defined in the include file <sys/syslog.h>.
For security reasons, syslogd will not append to log files that do not
exist (unless -C option is specified); therefore, they must be created
manually before running syslogd.
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 -T flag.
FILES
/etc/syslog.conf configuration file
/var/run/syslog.pid default process ID file
/var/run/log name of the UNIX domain datagram log socket
/var/run/logpriv UNIX socket for privileged applications
/dev/klog kernel log device
SEE ALSO
logger(1), syslog(3), services(5), syslog.conf(5), newsyslog(8)
HISTORY
The syslogd utility appeared in 4.3BSD.
The -a, -s, -u, and -v options are FreeBSD 2.2 extensions.
BUGS
The ability to log messages received in UDP packets is equivalent to an
unauthenticated remote disk-filling service, and should probably be
disabled by default. Some sort of inter-syslogd authentication mechanism
ought to be worked out. To prevent the worst abuse, use of the -a option
is therefore highly recommended.
The -a matching algorithm does not pretend to be very efficient; use of
numeric IP addresses is faster than domain name comparison. Since the
allowed peer list is being walked linearly, peer groups where frequent
messages are being anticipated from should be put early into the -a list.
The log socket was moved from /dev to ease the use of a read-only root
file system. This may confuse some old binaries so that a symbolic link
might be used for a transitional period.
FreeBSD 13.1-RELEASE-p6 July 2, 2018 FreeBSD 13.1-RELEASE-p6
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