Syslog is a deamon that runs on every Linux box for collecting local system messages. It can also be configured to send these messages to a remote syslog server. The syslog server also runs the same syslog but with an option set to accept remote messages. There are variants available in addition to the standard sysklogd installed on many Linux distributions, namely rsyslog and syslog-ng but these will not be discussed here.

Setup Server

  • If it exists edit /etc/sysconfig/syslog or edit /etc/init.d/syslog and edit the line which contains SYSLOGD or SYSLOGD_OPTIONS and add the following arguments -r -m0 . This will set it up to accept remote connections and ignore the --- MARK --- lines respectively.

Setup Client

  • Add the following to /etc/syslog.conf
*.*         @syslog-server
Cisco IOS
conf t
logging syslog-server
logging trap errors
ervice timestamps log datetime
logging on

Full syntax:

router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
router(config)#logging ?
  Hostname or A.B.C.D  IP address of the logging host
  alarm                Configure syslog for alarms
  buffered             Set buffered logging parameters
  buginf               Enable buginf logging for debugging
  cns-events           Set CNS Event logging level
  console              Set console logging parameters
  count                Count every log message and timestamp last occurance
  delimiter            Append delimiter to syslog messages
  discriminator        Create or modify a message discriminator
  esm                  Set ESM filter restrictions
  event                Global interface events
  exception            Limit size of exception flush output
  facility             Facility parameter for syslog messages
  filter               Specify logging filter
  history              Configure syslog history table
  host                 Set syslog server IP address and parameters
  ip                   IP configuration
  listen               MWAM remote console and logging listen enabler
  message-counter      Configure log message to include certain counter value 
  monitor              Set terminal line (monitor) logging parameters
  on                   Enable logging to all enabled destinations
  origin-id            Add origin ID to syslog messages
  persistent           Set persistent logging parameters
  queue-limit          Set logger message queue size
  rate-limit           Set messages per second limit
  reload               Set reload logging level
  source-interface     Specify interface for source address in logging transactions
  system               enable/disable System Event Log
  trap                 Set syslog server logging level
  userinfo             Enable logging of user info on privileged mode enabling

Show logging status:

router# show logging
Cisco CatOS
set logging server syslog-server
set logging server severity 3
set logging timestamp enable
set logging server enable

There are 8 logging levels:

  • 0 emergencies
  • 1 alerts
  • 2 critical
  • 3 errors
  • 4 warnings
  • 5 notification
  • 6 informational
  • 7 debugging

Syslogging is not native in Windows but there are 3rd-party tools available such as


Category:Linux Category:Networking