Question - check_by_ssh

[bosecorp]

what are the things that I need to consider If I want to move away from NRDS when monitoring devices with SSH instead

any best practices I should consider from the SSH configuration perspective, more from the nagios xi server perspective. Primary because I have abour 300 servers and that means that the nagios ssh will initiate that amount of ssh sessions

[bwallace]

Assuming you are going to gravitate towards active checks, myself and a colleague ran a quick test. We measured the time it takes to run the same command from Nagios XI (CLI) via NRPE, then via check_by_ssh:
NRPE: 0m0.006s
SSH: 0m0.269s

Of course these results are going to vary from system to system, but it seems the key exchange is what took the longest. The act of encrypting the check results is a matter of bytes and did not account for much in THIS scenario.
Given the vast number of variables involved, we do not have an established bass line in regards to the hit on resources check_by_ssh will introduce.There is a spirited discussion on the topic here, and nobody seems have noticed much of a performance impact when using check_by_ssh:

[url]http://serverfault.com/questions/2 ... rpe-vs-ssh[/url]

Here is our XI set-up guide for using check-by-ssh
https://assets.nagios.com/downloads/nag ... ng_SSH.pdf

- Hope this helps -

[bosecorp]

Thanks for the input.

NRPE requieres and agent. How mature is NRPE and how flexible is?

NRPE doesn't seem to support AIX 7.1. and it doesn't support RHEL 7

also the agent installation requires a lot packages to be installed, and that is a problem is the device is behind a firewall

[lmiltchev]

NRPE requieres and agent. How mature is NRPE and how flexible is?

I would say NRPE is a pretty mature project. NRPE-1.3 was released in 2002. It is pretty flexible, too. You can set up a variety of checks, including running custom scripts, running checks against remote servers, etc.

NRPE doesn't seem to support AIX 7.1. and it doesn't support RHEL 7

We always recommend running our Linux agent installer script, as it makes installing NRPE, and Nagios plugins very simple. RHEL 7 and CentOS 7 are supported.

As for installing NRPE on AIX 7.1, you could download the source and build it yourself.
http://www.ehow.com/how_8791563_install-nrpe-aix.html

also the agent installation requires a lot packages to be installed, and that is a problem is the device is behind a firewall

You will need to open the "default" NRPE port 5666 in the firewall, unless you decide to use a different port. You can even install NRPE in an offline environment. We don't have an offline installer, but you can download the Linux agent on the different machine (with Internet access) and moving it over to your server, i.e in the "/tmp/" directory.

Run:

Code: Select all

cd /tmp
tar zxvf linux-nrpe-agent.tar.gz
cd /tmp/linux-nrpe-agent
touch installed.repos
touch installed.prereqs

Find a way to install the prerequisites manually on this machine - autoconf, gcc, glibc, libmcrypt-devel, make, openssl-devel, sudo, sysstat, xinetd, and bc.

Lastly, run the fullinstall script:

Code: Select all

./fullinstall

Hope this helps.

[bosecorp]

Thanks a lot. that helped a lot. you can close this ticket