[agent]: Communication failed: [SSL: SSLV3_ALERT_HANDSHAKE_FAILURE] sslv3 alert handshake failure (_ssl.c:2546)

[chiwuz (Simi)]

Hi.

I get this error [agent]: Communication failed: [SSL: SSLV3_ALERT_HANDSHAKE_FAILURE] sslv3 alert handshake failure (_ssl.c:2546) but just on some servers. I’ve tried everything… uninstalling and reinstalling the agent, troubleshooting and so on… all I could find was this:

Request failed. (invalid peer certificate contents: invalid peer certificate: UnknownIssuer)
[rustls::conn] Sending fatal alert HandshakeFailure

ss -tulpn |grep 6556
tcp LISTEN 0 4096 *:6556 : users:((“cmk-agent-ctl”,pid=1474638,fd=9))

CMK version:
Version: 2.2.0p12
OS version:
Debian GNU/Linux 12 (bookworm)

[ChristianM (Christian Michaelski)]

Hi.
Did you try to remove the TLS certificate for the agent encryption from the given host?
There is a button in the host menu when you edit the host. Did you also try to rum the agent communication in legacy mode?

RG, Christian

[chiwuz (Simi)]

Hi, thank you for advice. Removing TLS certificate didn’t work, but running agent communication in legacy mode, fixed my issue. Unfortunately I could not find why it was not possible to arrange the agent to work via cmk-agent-ctl or via TLS on Debian GNU/Linux 12 (bookworm)