NRPE Destination port: 5666 Source Port:?


When nagios makes a NRPE query to a host we know we want to hit the target host’s port 5666.

But what’s the port that nagios uses to make this query?

When the target host replies back to Nagios, what port does the system use?

Is it all on 5666?

Found a few documents online such as the below but not sure if this is the answer to what I’m looking for.

Thanks in advance for your insights.


Since it is a regular TCP connection the return port (source port) will be choosen randomly by the check_nrpe command on your nagios server… As most (all?) firewalls handle TCP you do not have to configure this though so it normally does not matter