I just upgraded a simple Ubuntu webserver from 9.10 to 10.04.1 and our nagios claims UNKNOWN for the single snmp check we run against it. It was working previously, so this baffles me.
I installed the plugins on my desktop and get this output when I run it (obfuscated where appropriate:
$: ./check_snmp_storage.pl -H $HOSTNAME$ -C $pword$ -m / -w 90 -c 95 ERROR: Description/Type table : No response from remote host $HOSTNAME$`
So I installed nagios plugins on the webserver and get the same output, unless I use localhost for $HOSTNAME$.
The snmpd.conf is pretty trivial, and I wonder if that's the problem?
syslocation "ESX Server" syscontact email@example.com rocommunity pword disk / load 30 30 30