Cannot read data from SSH server" happens when SSH agent script includes |(pipe)

[sheine]

Hi community,
we're using zabbix 6.4.7 and I tried to get some info via ssh from a linux server. Each time I use a pipe, the error appears "cannot read data from ssh server". If I remove the pipe symbol it works...
Any suggestions?
Thanks a lot

[cyber]

Examples?
You may need to escape that pipe or it breaks your command line maybe...

[sheine]

My example:field executed script from my host item is filled with: cat /etc/os-release | grep -oP 'PRETTY_NAME="\K[^"]+' This delivers "ssh read error" most the time, sometimes (after 2 hours or 5 hours, it differs) there is an answer. If I remove the part with the pipe I get an answer. Behavior is described in ZBX-21337

[dimir]

Did you go through notes that were added in that ticket?

https://www.zabbix.com/documentation/current/en/manual/installation/known_issues#ssh-checks

[sheine]

I didn't see these notes - we have made an update of ubuntu 20.04 to 22.04 and now we can use the pipe symbol without errors! Thank's a lot.

[cyber]

• Using the pipe "|" in the SSH script may lead to a "Cannot read data from SSH server" error. In this case it is recommended to upgrade the libssh library version. See also ZBX-21337 for details.

I guess upgrading OS also updated libssh...