Nagios Support Forum

I am looking for a Nagios XI solution for monitoring hosts that are not assigned static IP Addresses. I have not yet used passive monitoring however if this is a candidate I'd be interested in how it would work.

Thanks in advance

Passive monitoring would certainly be a solution, unless you want to manage the DNS for the DHCP machines

Passive monitoring is essentially when a host checks itself and sends the results back to Nagios, as opposed to Nagios initiating the check. There are a variety of methods for doing so, and you can take a look at them here:

http://assets.nagios.com/downloads/nagi ... ios-XI.pdf

Thanks for the quick reply. How are host checks handled with passive checks? In other words how do we check that the host is up?

If you are receiving passive results from the host, you can be pretty sure that the host is up :)

Otherwise there is an option called Freshness Checking where if you do not receive a passive result from a host for X minutes, you initiate an active check on the host. That might be harder to do for a DHCP-based device, so in those cases if you don't get a result within the freshness interval you can treat the host as DOWN.

tmcdonald wrote:If you are receiving passive results from the host, you can be pretty sure that the host is up

Otherwise there is an option called Freshness Checking where if you do not receive a passive result from a host for X minutes, you initiate an active check on the host. That might be harder to do for a DHCP-based device, so in those cases if you don't get a result within the freshness interval you can treat the host as DOWN.

Exactly, you set the freshness check to the interval you want and then just use the "check_dummy" command as the active check for the host and have it set to critical with some sort of message like "CRITICAL: Have not received any data in X minutes"

Thanks for the great feedback all. Currently I have a standalone Nagios XI monitoring server in place. I will have to look at configuring the system to allow Passive Checks.

Great! Do you have any further questions on this topic before we lock the thread? Of course, feel free to open a new one with questions on passive checks, or anything else that comes to mind!

We can lock this thread.

Thanks!