SYSLOGD(8) System Manager's Manual SYSLOGD(8) NAME syslogd -- log systems messages SYNOPSIS syslogd [-46Adknsuv] [-a allowed_peer] [-b bind_address] [-f config_file] [-m mark_interval] [-p log_socket] [-P pid_file] [-l path] DESCRIPTION The syslogd daemon 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 Forces syslogd to use IPv4 addresses only. -6 Forces syslogd to use IPv6 addresses only. -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 op- tion is specified, syslogd tries to send the message to all ad- dresses. -a allowed_peer Allow allowed_peer to log to this syslogd using UDP datagrams. Multiple -a options may be specified. Allowed_peer can be any of the following: ipaddr/masklen[:service] Accept datagrams from ipaddr (in the usual dotted quad notation) with masklen bits being taken into account when doing the address comparison. ipaddr can be also IPv6 address by en- closing the address with `[' and `]'. If specified, service is the name or number of an UDP service (see ser- vices(5)) the source packet must belong to. A service of `*' allows packets being sent from any UDP port. The de- fault 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 ad- dress lookup yields domainname for the sender address. The meaning of service is as explained above. *domainname[:service] Same as before, except that any source host whose name ends in domainname will get permission. The -a options are ignored if the -s option is also specified. -b bind_address Specify one specific IP address or hostname to bind to. If a host- name is specified, the IPv4 or IPv6 address which corresponds to it is used. -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 Specify the pathname of an alternate configuration file; the de- fault is /etc/syslog.conf. -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 Select the number of minutes between "mark" messages; the default is 20 minutes. -n Disable dns query for every request. -p Specify the pathname of an alternate log socket to be used instead; the default is /var/run/log. -P Specify an alternative file in which to store the process ID. The default is /var/run/syslog.pid. -l Specify a location where syslogd should place an additional log socket. Up to 19 additional logging sockets can be specified. The primary use for this is to place additional log sockets in /var/run/log of various chroot filespaces. -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. -u Unique priority logging. Only log messages at the specified prior- ity. 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 pri- ority 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. The syslogd daemon reads its configuration file when it starts up and when- ever it receives a hangup signal. For information on the format of the configuration file, see syslog.conf(5). The syslogd daemon reads messages from the UNIX domain socket /var/run/log, from an Internet domain socket specified in /etc/services, and from the special device /dev/klog (to read kernel messages). The syslogd daemon 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 ex- ist; therefore, they must be created manually before running syslogd. 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 /dev/klog kernel log device SEE ALSO logger(1), syslog(3), services(5), syslog.conf(5) HISTORY The syslogd command 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 dis- abled 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 doesn't pretend to be very efficient; use of nu- meric IP addresses is faster than domain name comparison. Since the al- lowed peer list is being walked linearly, peer groups where frequent mes- sages 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 filesystem. This may confuse some old binaries so that a symbolic link might be used for a transitional period. FreeBSD 4.7 October 12, 1995 SYSLOGD(8)
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