**CHECK_NRPE: Error - Could not complete SSL handshake* - * NSClient++ version: **0.6.0.1**

[AntMCE]

Describe your issue and tell us how to reproduce it. CHECK_NRPE: Error - Could not complete SSL handshake

PLEASE PROVIDE COMMAND HERE check_nrpe -H x.x.x.x -p 5666 -u -t 180 -c CheckCPU -a warn=85 crit=90 time=10s

Expected Behavior

Should read check value output

• NSClient++ version: 0.6.0.1
• OS and Version: Windows Server 2012
• Checking from: Shinken installed on centos6 with OpenSSL 1.0.2k-fips
• Checking with: check_nrpe

Additional Details

[/settings/NRPE/server]

ssl options =

port = 5666

insecure = true

verify mode = none

allow nasty characters = true

allow arguments = true

use ssl = true

NSClient++ log:

nscp failed to establish secure connection: unsupported protocol

[Prathameshhankare]

@AntMCE, I am not sure if your issue was similar to mine. I used Centos7 on which the check_nrpe command worked with no issue however after I migrated to Ubuntu 22.04 the check_nrpe threw the same error you mentioned. To mitigate the problem I had to change the DH key size on my Windows server to 2048 bit instead of the default 512 bit. Since I am monitoring 1000+ domain controllers(Windows Servers) I could not make the change manually hence created a PowerShell script that does the work for me. Check out my GitHub repository if the script can help you as well.

https://github.com/Prathameshhankare/nsclientpp_dh-key-updater