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Syslog Analyzer

The syslog analyzer lets you browse Cisco syslog messages that are collected by the syslog deamon. Only Cisco syslog messages are supported.

The back-end

A requirement for this tool is that a syslog daemon is running on your NAV machine collecting syslog messages from your Cisco gear. Unfortunately the NAV Syslog Analyzer only supports Cisco syslog messages, other messages will be ignored (an improvement is on our road map).

We recommend that you in your syslog configuration log syslog messages from your network equipment to two parallel files, one that is read (and emptied) by NAV and another that is untouched by NAV. The latter can be inspected as usual from shell (you should rotate as you do with other ever-growing log files). The one that NAV reads and empties is configured in the nav/etc/logger.conf file. It is the NAV background process logengine that does this job. Every minute the log file is checked for new messages. If any, they are removed from the file, parsed and inserted into the NAV logger database.

Cisco syslog message semantics and the NAV logger database

The NAV logger database takes advantage of the fact that Cisco syslog messages have a predefined structure. Briefly explained a Cisco message type consists of three elements interconnected with hyphen (-). The three elements are:

  1. Area/topic
  2. Priority number, eight values: 0=emergency, 1=alerts, 2=critical, 3=errors, 4=warnings, 5=notifications, 6=informational, 7=debugging.
  3. A descriptor within the area/topic.

Some examples:


For any given syslog message, the following are typically found after the syslog server's timestamp:

  • The name of the originating device
  • A timestamp
  • The Cisco message type descriptor
  • The text of the message being logged

The NAV logger database models this structure.

Some valid examples are:

May 27 08:32:58 2002 May 27 08:32:53 MET +02:00 %CDP-4-NVLANMISMATCH:Native vlan mismatch detected on port 4/2
Feb  8 12:58:40 316371: Feb  8 12:58:39.873 MET: %SEC-6-IPACCESSLOGDP: list 112 permitted icmp -> (0/0), 1 packet
Mar 25 10:54:25 somedevice 72: AP:000b.adc0.ffee: *Mar 25 10:15:51.666: %LINK-3-UPDOWN: Interface Dot11Radio0, changed state to up

Incidentally, the log parsing engine has a bug in NAV versions prior to NAV 3.5.3, which cause it to crash if the following format is used (i.e. a year in the originating device's timestamp):

Mar 20 10:27:26 sw_1 607977: Mar 20 2009 10:20:06: %SEC-6-IPACCESSLOGP: list fraVLAN800 denied tcp x.x.x.x(1380) -> y.y.y.y(80), 2 packets

The Syslog Analyzer front-end tool

The Syslog Analyzer presents a search form where you can retrieve information of your interest. You may for example see all messages the last 24 hours that are of severity 3, or that has been received from a given switch. In the presented result each message type from a given source box is listed with the number of occurrences seen for this particular message type. By clicking on the number of occurrences further details will be listed.

If there are cases of parsing errors, you can see these (i.e. where the logger process is not able to understand the message).


In etc/logger.conf you can define:

  • path to the syslog file.
  • character set of syslog file (i.e. ISO-8859-1).
  • the number of days messages of a given priority should be stored in the database.
  • priority exceptions: This can be useful in cases were you disagree with the predefined severity given by Cisco. A given message type may be given a higher or lower priority, as you define.
sysloganalyzer.txt · Last modified: 2009/03/25 14:00 by morten