Nagios Support Forum

Posted: **Sun Dec 08, 2019 4:29 am**

Hi all,
I am doing a testing before implement monitoring to my company machines.

I am using a Linux Machine (installed Nagios Core) to monitor a Windows 10 Desktop with NSCP (Latest Version, 0.5.2.35) installed. All the installation is running well. Even the command

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./check_nrpe -A [CA] -C [CLientCert..pem] -K [clientKey] -H [IP] -c [checkmem]

it returns what I expected.

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OK: committed: Total: 12.06GB - Used: 9.611GB (79%)

But the things is when I check the log file from the NSCP (from Windows), I saw

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debug:c:\source\master\include\nrpe/server/protocol.hpp:92: Accepting connection from: [__IP__], count=1
error:c:\source\master\include\socket/connection.hpp:276: Failed to establish secure connection: tlsv1 alert unknown ca: 1048

So I feel curios and weird when I saw the log. Why is the unknown CA happened ?

PS: I follow the guide from https://support.nagios.com/kb/article.php?id=519
PS2: I created the CA and sign from my Linux Machine and copy the those cert and key to Windows

Below is my nsclient.ini file

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[/settings/NRPE/server]
port = 5666
extended response = 1
use ssl = 1
allow arguments = 1
allow nasty characters = 1
insecure = 0
veryify mode = peer-cert
ssl options = no-sslv2,no-sslv3
allowed ciphers = ALL:!ADH:!LOW:!EXP:!MD5:@STRENGHT
certificate = ${certificate-path}/client2_cert.pem
certificate key = ${certificate-path}/client2_cert.key
ca = ${certificate-path}/ca2_cert.pem
;DH key = security\nrpe_dh_512.pem
;certificate format = PEM

Posted: **Tue Dec 10, 2019 7:56 pm**

The "unknown ca" message occurs with self signed certificates. Here's detailed information on these sorts of messages:

https://support.nagios.com/kb/article/s ... s-598.html

If you are connecting OK with your commands then everything should be OK and you can ignore the error.

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