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Following PRTG update, "Failed to connect. "Please check the SSH log of the target device..."

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After the update (V19.4.53.1912), ssh sensors were all down with this error message:

"Failed to connect. Please check the SSH log of the target device or try the Compatibility Mode of the sensor's SSH engine and consider updating the target system's operating system. Reason: ssh_connect failed (-1)kex error : no match for method server host key algo: server [ecdsa-sha2-nistp256], client [ssh-rsa]"

We tried the compatibility mode and it work for many ssh sensors. Some sensors were using a different configuration (user/pass with custom port) and using the compatibility mode did not work.

I tried configuring the sensor with a public/private key generated with Putygen but I get this error message now: "Invalid key exchange algorythm".

What should I do to solve this issue?

I currently have an issue with a Centos 7 appliance named "LiquidFiles" that I don't want to install SNMP, or change the firewall rules or change port (ssh 222)....

It was working so well before that update...

algorythm exchange invalid key ssh

Created on May 30, 2022 5:29:22 PM



1 Reply

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Hi there,

Please check following article first, since we updated SSH libraries with the latest version available: Topic 90689. I hope this helps to find a solution.

Kind regards

Felix Wiesneth - Team Tech Support

Created on Jun 2, 2022 2:30:42 PM by Felix Wiesneth [Paessler Support]




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