This is a plugin package for Nagios.  Quoting from the
snmp4nagios home page:

SNMP4Nagios is a package of Nagios plugins which use SNMP
to query hosts. While some of the plugins use standard MIBs,
most are designed for vendor specific agents.

Unlike other Nagios plugins, they are able to scan hosts for
objects which can be monitored. They also can keep performance
logs and draw plots of these using Tobias Oetiker's RRDTool.

Currently devices by Brocade, Cisco, Compaq/HP and Network Appliance
as well as computers running Microsoft Windows or Net-SNMP
and uninterruptable power supplies are supported.

WWW: http://snmp4nagios.sourceforge.net/