[CentOS] SNMP working on localhost, failing remotely

Colosus · 03-23-2007, 05:22 PM

Hello all,

I'm hoping someone here can help me out as I'm out of ideas. I recently installed snmp on 3 CentOS servers and have a FreeBSD machine running on my desktop with Cacti, et al. Of the 3 servers, only 1 is working. I installed them all the same way using yum and configuring snmpd.conf for my setup. Cacti is able to communicate with one of the machines and all the machines can snmpwalk using localhost, but 2 of them can not do so remotely.

I changed the configuration back to default settings and public community just to see if I could even get a "system" response, but it reports "Timeout: No Response from <host>". I disabled iptables on all the hosts and made sure selinux was disabled and there are no hardware firewalls in place.

The snmp communication is happening over the internet, the boxes are not on the same network. Is there any reason why I would continue to get timeouts to these other two hosts? Thanks.

dxqcanada · 03-23-2007, 08:51 PM

Does nmap show it open ... if you run it from the remote host ?

Code:

n600c ~ # nmap 192.168.1.102 -sU -p 161

Starting Nmap 4.20 ( http://insecure.org ) at 2007-03-23 21:50 EDT
Interesting ports on 192.168.1.102:
PORT    STATE         SERVICE
161/udp open|filtered snmp

Colosus · 03-23-2007, 09:11 PM

Quote:

Originally Posted by dxqcanada

Does nmap show it open ... if you run it from the remote host ?

Code:

n600c ~ # nmap 192.168.1.102 -sU -p 161

Starting Nmap 4.20 ( http://insecure.org ) at 2007-03-23 21:50 EDT
Interesting ports on 192.168.1.102:
PORT    STATE         SERVICE
161/udp open|filtered snmp

PORT STATE SERVICE
161/udp open|filtered snmp

Nmap finished: 1 IP address (1 host up) scanned in 6.729 seconds

Yep.

Colosus · 03-24-2007, 12:45 AM

So I did some tcpdumps on the machines. One was getting the snmpget requests and one wasn't. I'm going to assume the one that isn't is due to a host firewall that I'm not aware of (leased boxes) and I'll deal with that on Monday.

The other was an unknown configuration issue. After removing and reinstalling net-snmp and net-snmp-utils and editing the conf file (to exactly what it was before) it works fine now. *shrug* Maybe I typo'd something that I couldn't see.

Anyway, thanks for the help.