Nagios Support Forum

Posted: **Wed May 21, 2014 12:36 pm**

Hey all, I just moved my Nagios monitoring from my FreeBSD server to my CentOS 6.5 server. I'm now in the clean-up phase and I've hit a snag -- I'm unable to get monitoring to work on my Linux servers.

The error:

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CHECK_NRPE: Error - Could not complete SSL handshake.

Both the server and client now have the same version of nrpe (I just installed the new nrpe on the client but still no joy):

Client:

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NRPE - Nagios Remote Plugin Executor
Copyright (c) 1999-2008 Ethan Galstad ([email protected])
Version: 2.15
Last Modified: 09-06-2013
License: GPL v2 with exemptions (-l for more info)
SSL/TLS Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher required

Server:

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NRPE Plugin for Nagios
Copyright (c) 1999-2008 Ethan Galstad ([email protected])
Version: 2.15
Last Modified: 09-06-2013
License: GPL v2 with exemptions (-l for more info)
SSL/TLS Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher required

I even tried including the -n switch but that didn't help:

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[root@FreeNag objects]#  /usr/local/nagios/libexec/check_nrpe -H 192.168.2.83 -n
CHECK_NRPE: Error receiving data from daemon.
[root@FreeNag objects]#  /usr/local/nagios/libexec/check_nrpe -H 192.168.2.83
CHECK_NRPE: Error - Could not complete SSL handshake.

The only possible issue I can find is that the SSL versions are a little off:

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root@srvBackup:/usr/local/nagios/etc# openssl version
OpenSSL 0.9.8o 01 Jun 2010

[root@FreeNag objects]# openssl version
OpenSSL 1.0.1e-fips 11 Feb 2013

I tried upgrading srvBackup (through apt-get) but no upgrades are available, then I removed and reinstalled openssl but it's the same version. Should I try to remove openssl and try reinstalling from another source?

Thanks,

Joe B

Posted: **Wed May 21, 2014 12:49 pm**

jbruyet wrote:The only possible issue I can find is that the SSL versions are a little off:

There was a hard break in ssl supported version, so this could very well be the case.
When you try to connect, the error should be logged in the nrpe daemon server's messages.

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tail -20 /var/log/messages

Posted: **Wed May 21, 2014 1:05 pm**

Hi abrist, I can't find anything nrpe-related:

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[root@FreeNag objects]# grep nrpe /var/log/messages
[root@FreeNag objects]#

That's on the server and the client.

Thanks,

Joe B

Posted: **Wed May 21, 2014 3:40 pm**

Did you add nagios server's IP to the "allowed_hosts" line in the "nrpe.cfg" file on the client (or to the "only_from" line in the "/etc/xinetd.d/nrpe" if nrpe is running under xinetd)?

Posted: **Wed May 21, 2014 4:52 pm**

Thank you, lmiltchev, for that answer. All of my Linux servers are now all green except for one, and that one is slowly getting greener. What a rookie mistake -- I made the changes to my Windows servers but never even thought about my Linux servers. AND, with the SSL error message I would never have thought about looking for the answer in an allowed_hosts section of a config file.

Thanks again,

Joe B

Posted: **Wed May 21, 2014 4:55 pm**

The good thing about mistakes is that you (hopefully) learn something from them!

Is it safe to close this up now?

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