Monitoring a HP Procurve 5412zl switch interface with Nagios (SNMP)

8.50am. Yesterday I had a couple of minutes spare to build on my Nagios setup. Since setting up Nagios I have been looking into monitoring the fibre interfaces that connect my core and satellite switches. Unfortunately I was not able to find any good examples of this done before so I set out to try and set it up myself.

To complete this task I used the check_snmp plugin as a base and built up my own command to check the interface status. After running though an snmpwalk on the switch (snmpwalk -v1 IPHERE -c public >~/Procurve_snmpwalk) I discovered the following MIBS that I can use:

ifSpeed.X (speed of link)
ifOperStatus.X (link up or down)
ifOutOctets.X & ifInOctets.X
ifOutUcastPkts.X & ifInUcastPkts.X
ifOutNUcastPkts.X & ifInNUcastPkts.X

The X indicates the Port ID, however to use this integer we need to check what ID links to what interface. This can be achieved by performing a query on the ID using the ifDescr.X MIB. The results to my snmpwalk already gave me the results I required however they can be checked manually on the command line via:

/usr/lib64/nagios/plugins/check_snmp -H %HostnameHere% -C public -o ifDescr.X

By changing the value of X, I am presented with the interface name. For example in my case ID 2 = Port A2 on the switch.

Now I know what the interface ID is for the port is I can start to build up commands based on the MIBS i discovered above. To start with I wanted a simple interface check (up/down) so I wrote the following to the /etc/nagios/objects/commands.cfg file:

define command{
     command_name check_interface_up
     command_line $USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o $ARG2$ -w 0:1 -c 0:1 -l 'Link Status'
}

I have set the warning & critical ranges to 0:1. I am unsure if this is the best way to do it, but it does work. The switch returns 1 for interface up and 2 for interface down.

I then added the following to my switch template:

define service{
     use generic-service
     host_name Block-B-5412zl
     service_description Block-A-3500yl uplink 2 status
     check_command check_interface_up!public!ifOperStatus.2
}

Using the ! symbol as a separator I am able to pass different variables to the command; $ARG1$ and $ARG2$ .

$ARG1$ = the community string checked
$ARG2$ = This is where I define the SNMP MIB ifOperStatus.2, however I can replace this with different MIBs that I mentioned earlier.

Thats pretty much it, reload nagios and I am now able to monitor switches interfaces. Next task is monitoring the traffic flowing through the interfaces by monitoring ifOutUcastPkts.X & ifInUcastPkts.X in cacti.