Monday, July 26, 2010

CHECK_NRPE: Error - Could not complete SSL handshake

Recently I have been auditing our servers versus what we check in nagios versus what we need to do when a system is rebooted during routine maintenance. I found that two of our servers have been left out of nagios monitoring even though they are on my maintenance checklist, and they have software that I still start by hand (I KNOW IT'S NOT A BEST PRACTICE!).

Both servers had NRPE installed and configured (mostly), one of them even had a configuration file on the nagios server but it wasn't enabled (hostname.disabled instead of hostname.cfg). The other server needed a configuration file, but even then it wasn't working, so here are my troubleshooting steps:

1) Check to see that NRPE is compiled and installed. [It was]
2) Check that NRPE was listening (netstat -an | grep 5666) [It was]
3) Check that NRPE was listed in /etc/services [It wasn't]
4) Check the NRPE config file (/etc/xinetd.d/nrpe) for "only_from =" [It wasn't]

So I added the service definition to /etc/services and the nagios server IP to the only from line and restarted xinetd (service xinetd restart) and I was finally able to connect from my nagios server.

All of this is on CentOS 5.5 for both the server and the client.

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