These are a few plugins we wrote to do system checks through SNMP. Yes, there are quite a few other snmp plugins, but none of them met our requirements. These plugins are designed to match the functionality and output of the existing non-snmp plugins that come with the base nagios-plugins package.

check_snmp_disk.pl
This plugin checks the disk space of any number of disks through SNMP. It allows you to specify warning and critical thresholds as either kilobytes of disk space, or percentages. It also allows you to specify exactly which disks you want to check with inclusion and exclusion filters. This plugin has only been tested to work with the Net-SNMP and UCD-SNMP packages.

check_snmp_load.pl
This plugin checks the load averages of the remote machine through SNMP. It allows you to specify warning and critical levels for the 1 minute, 5 minute, and 15 minute averages.

check_snmp_procs.pl
Checks if any number of given processes are running on the remote host. It allows you to specify the proc name (with regex support) and the warn and critical ranges (min and max) for each process.

Requirements
These modules require the Net::SNMP module from CPAN to be installed. You can get it from cpan.org or if you have the CPAN module installed, you can run this command:

   perl -MCPAN -e 'install Net::SNMP'

Installation
Install the plugins in your nagios/libexec directory and configure nagios to use them like you would any other plugin.

Download
nagios_snmp_plugins-0.1.tar.gz