Monitoring the output of an SNMP query

In this recipe, we'll learn how to use the check_snmp plugin to monitor the output given by Simple Network Management Protocol (SNMP) requests.

Despite its name, SNMP is not really a very simple protocol, but it's a very common method for accessing information on many kinds of networked devices, including monitoring boards, usage meters, and storage appliances, as well as workstations, servers, and routing equipment.

Because SNMP is so widely supported and typically able to produce such a large volume of information to trusted hosts, it's an excellent way to gather information from hosts that's not otherwise retrievable from network services. For example, while checking for a PING response from a large router is simple enough, there may not be an easy way to check properties, such as the state of each of its interfaces, or the presence of a certain route in its routing tables.

Using check_snmp in Nagios Core allows automated retrieval of this information...