====== Logging ======

===== Update for 20.7 =====
There is a option to disable legacy circular logging: [[https://docs.opnsense.org/manual/settingsmenu.html#local-non-circular-logs|Local (non circular) logs]]
And code change: [[https://github.com/opnsense/core/issues/4068|Syslog: optionally disable legacy (clog) logging]]

===== Pre 20.7 =====

DO NOT INCRESE CIRCULAR LOG SIZES!
SYSLOG CLOG support is implemented using mmap-ed files. So with log file size 100MB it makes HDD 100% busy and make system not responsive.


  * ''syslogd'' is used as local system logger
    * <code bash>/usr/local/sbin/syslogd -s -c -c -P /var/run/syslog.pid -p /var/run/legacy_log -S /var/run/legacy_logpriv -k -s -s -f /var/etc/syslog.conf</code>
      * ''-s'' secure mode - do not log from remote machines
      * ''-c -c'' disable compression of repeated lines for all instances
      * ''-S'' additional socket for privileged applications
      * ''-k'' do not translate ''kern'' to ''user''
      * ''-s -s'' no network - no remote logging
  * ''syslog-ng'' is spawned to forward logs to remote hosts
Circular log files:
  * There is not log rotation. To keep longer log history, increase log size to i.e. 100M. There are aroung 22 log files, so 22*100M gives 2.2GB occupied space.
  * to keep log files at constant size, syslogd is compiled with clog support. [[http://software.wheelhouse.org/syslogd/|Circular log support for FreeBSD syslogd]]
  * Config file ''syslog.conf'' contain special ''%'' marker to signal that log file is a circular log file
  * Each log file is initialized to maximum size by tool ''clog''.
  * At the end file, special information structure is stored for CLOG.


<code bash>
# tail z dnsmasq.log file
clog -f /var/log/dnsmasq.log
</code>