MRTG and SNMP and Timeout: No Response

by Simon at 17:47 26/05/08 (Blogs::Simon)

After configuring SNMP on a new host to be monitored, then trying a test snmpwalk from a separate monitoring host and getting back:

Timeout: No Response from (monitored host)

... then this is easily fixed when you remember after 3 hours that you should probably have opened the firewall on the MONITORING system as well as the one being monitored, so the SNMP answer can get back in.

Duh!

ie:

On the host being monitored the firewall has to allow in UDP with destination port 161. These are the SNMP probes from the monitor.

On the monitoring host the firewall has to allow in UDP with a source port of 161 from the IP of the host being monitored. These are the answers to the SNMP probes.

That's an afternoon of my life I won't get back. :-/
--
simon

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