Nagios Monitoring of Switches and Routers
Written by David Noel-Davies   
This example shows how the Nagios monitoring tool can be used to monitor the message count of a queue and the free memory of a Router or Switch using the OID from an SNMPwalk.

nagios.cfg

In Nagios' main configuration file we add a new object configuration file where we define the entries to monitor the SwiftMQ Router:

      cfg_file=/usr/local/nagios/etc/objects/swiftmq.cfg

First, we define the host we want to monitor (the machine where the SwiftMQ Router runs):

      define host{

              use                     generic-host            ; Name of host template to use

                                                              ; This host definition will inherit all variables that are defined

                                                              ; in (or inherited by) the linux-server host template definition.

              max_check_attempts      10

              host_name               msgserver1

              alias                   msgserver1

              address                 192.168.0.47

              }

Next we define the host group "SwiftMQ-Servers" where this machine belongs to:

      define hostgroup{

              hostgroup_name  SwiftMQ-Servers ; The name of the hostgroup

              alias           SwiftMQ Servers ; Long name of the group

              members         msgserver1      ; Comma separated list of hosts that belong to this group

              }

A command "check_snmpv2c" to check with SNMPv2:

      define command{

              command_name check_snmpv2c

              command_line $USER1$/check_snmp -H $HOSTADDRESS$ -P 2c $ARG1$

      }

And the service to monitor testqueue's messagecount. Note we use port 10061, the OID we determined with an SNMP walk on the machine (google it if need be), and set a warning level at 8000 and a critical threshold at 10000 messages:

define service{

  use                     generic-service ; Inherit values from a template

  host_name               msgserver1

  service_description     testqueue message count

  check_command           check_snmpv2c!-p 10061 -C public -o 1.3.6.1.4.1.16683.1.2.11.1.12.1.1.10.9.116.101.115.116.113.117.101.117.101 -c 10000 -w 8000

}

Finally the service to monitor the free memory of the router:

define service{

  use                     generic-service ; Inherit values from a template

  host_name               msgserver1

  service_description     Free Memory SwiftMQ router1

  check_command           check_snmpv2c!-p 10061 -C public -o 1.3.6.1.4.1.16683.1.2.1.1.10.1.1.2.7.114.111.117.116.101.114.49!5000!1000

}

Test

Now start Nagios, open the Nagios web console and send messages to "testqueue" (simply use the example "P2PSender" in samples/router_network