file: README.Nagios
author: Alexander Haderer
date: 17 Dec 2002
cvs: $Id: README.Nagios,v 1.1 2002/12/17 18:04:46 afrika Exp $
R E A D M E N A G I O S S E T U P
This file describes how to setup Nagios to monitor local or remote
kernel syslog messages. Nagios is a Network monitoring software and
can be found at http://www.nagios.org .
For remote monitoring Nagios requires the plugin check_snmp to work,
which uses NET-SNMP tools. NET-SNMP is a collection of SNMP utilities
and can be found at http://www.net-snmp.org .
This is only a brief description to give an idea how to set this up.
Read the manpages and docu to understand what you do.
The setup was done with Nagios 1.0, newer versions are assumed
to work also.
HOW TO 'local monitoring'
Read this if you want to monitor a kernel syslog file that is local
on the host running Nagios. fetchlog will run as a Nagios plugin.
1. install
Install fetchlog as described in the README. fetchlog's calling
convention is compatible with Nagios's plugin calling convention.
You can install fetchlog in the default location /usr/local/...
2. setup syslog
Setup syslog to write local kernel messages to /var/log/kernelmsg
as described in README.SNMP, 'HOWTO GET /POLLING', step 2-6'
Note: You can configure syslogd to act as a loghost: remote machines
send selected syslog messages to the loghost. Read the syslogd
manpage how to set this up.
3. Nagios config: new service check command
login as Nagios user, cd etc and edit configuration file command.cfg.
Add a new service check command by adding this line:
command[check_lkernel]=/usr/local/bin/fetchlog -F 35:75:330:bnos \
/var/log/kernelmsg /var/tmp/kernelbm
Note: Enter this as one single line.
4. Nagios config: new service
Edit config file hosts.cfg. Add a new service by adding this line:
service[host]=kernel;1;24x7;1;5;1;admin;720;24x7;0;1;1;;check_lkernel
where host is the Nagios name for the Nagios host and admin
is the contact group.
Note: This service is volatile and sends out notification immediately
after the first check failed. Further checks with error will result
to further notifications send out (volatile!)
4. Nagios config: email notification
Edit .../etc/hosts.cmd again and look for command[notify-by-email]
command string and command[host-notify-by-email] command string.
Check if the 'echo -e' command sends out the contents of the
$OUTPUT$ variable to the mail program:
.... TIME$\n\nAdditional Info:\n\n$OUTPUT$'" | /usr/bin/mail ...
5. Nagios restart
Change to Nagios home dir and check the new Nagios config
by running:
bin/nagios -v etc/nagios.cfg
If everything is ok restart Nagios. Test your new config by
creating some kernel log messages. Look in Nagios logfile.
Watch your email.
HOW TO 'remote monitoring'
Read this if you want Nagios to monitor remote logfiles using
check_snmp/NET-SNMP and fetchlog.
Please read first README.SNMP
CONVENTION
remote machine: A machine running NET-SNMP's snmpd as described in
README.SNMP, section 'HOW TO: GET / POLLING'. The snmpd will
offer SNMP clients (Nagios machine) the last new messages
of the kernel logfile.
Nagios machine: A machine running Nagios.
1. install:
Goto Nagios machine. Check if check_snmp plugin works. This
plugin requires NET-SNMP at the Nagios machine.
2. test check_snmp:
login as Nagios user, cd libexec, and try
./check_snmp -H ip_of_remote_machine -C donttell \
-o .1.3.6.1.4.1.2021.8.1.101.1 -s 'OK: no messages' -l kernel
where donttell is the SNMP community name and ip_of_remote_machine
is the IP adress or hostname of the remote machine.
Create some kernel messages at the remote machine and retry
the check_snmp plugin.
To see better formatted output you can do
printf "`./check_snmp ...`\n"
Note: Output will be scrambled if the fetched messages contains
the character '%', use conversion setting 'p' in fetchlog to
avoid this.
3. Nagios config: new service check command
login as Nagios user, cd etc and edit configuration file command.cfg.
Add a new service check command by adding this line:
command[check_rkernel]=$USER1$/check_snmp -H $HOSTADDRESS$ \
-C donttell -o .1.3.6.1.4.1.2021.8.1.101.1 \
-s 'OK: no messages' -l kernel
Note: Enter this as one single line.
4. Nagios config: new service
Edit config file hosts.cfg. Add a new service by adding this line:
service[remote]=kernel;1;24x7;1;5;1;admin;720;24x7;0;1;0;;check_rkernel
where remhost is the Nagios name for the net address of the
remote machine and admin is the contact group.
Note: This service is volatile and sends out notification immediately
after the first check failed. Further checks with error will result
to further notifications send out (volatile!)
4. Nagios config: email notification
Edit .../etc/hosts.cmd again and look for command[notify-by-email]
command string and command[host-notify-by-email] command string.
Check if the 'echo -e' command sends out the contents of the
$OUTPUT$ variable to the mail program:
.... TIME$\n\nAdditional Info:\n\n$OUTPUT$'" | /usr/bin/mail ...
5. Nagios restart
Change to Nagios home dir and check the new Nagios config
by running:
bin/nagios -v etc/nagios.cfg
If everything is ok restart Nagios. Test your new config by
creating some kernel log messages at the remote machine. Look
in Nagios logfile. Watch your email.
Happy monitoring!
SEE ALSO
Nagios - A network monitoring system formerly known as Netsaint
http://www.nagios.org
NET-SNMP - Various tools relating to the Simple Network
Management Protocol SNMP (NET-SNMP: formerly known as UCD- SNMP)
http://www.net-snmp.org
LEGAL
Nagios is a registered trademark of Ethan Galstad
EOF
