Snmpwalk timeout


Been stuck on this for a few hours, can’t seem to figure out the problem.

All the machines are running CentOS 5 X64
No iptables

I have a nagios box, DNS, hosting machine, Main website box

They are all behind a firewall.

I have snmp setup on all the boxes and the cofig files are identical (just " rocommunity public ")

I run a snmpwalk from the nagios box to DNS and it works fine. Same goes for the hosting machine.
However, when I try it for the main website box, I get a timeout (see below)

[nagios ~]# snmpwalk -v 1 -c public
Timeout: No Response from

Here’s an nmap from the nagios machine on the main website box (fyi: I ran this on the entire netblock and they all look the same)

[nagios ~]# nmap -sU -T5 -vv -p 161
Interesting ports on (
161/udp open|filtered snmp

I’m completely at a loss right now. Please help.