OpenSSH 8.0 - 8.2 ClientAlive issue

[Mervyn McMurray (mmcmurra)]

Hi,

I have recently upgraded from OpenSSH 7.5 to OpenSSH 8.0 (I know its old, but I have complications in a cross compiled environment).

After the upgrade I have noticed the Client Alive mechanism has stopped working. I operate in a environment where it is common for the TCP link between
client and server to get dropped after a period of inactivity, due to firewall configuration.

The issue seems to be the patch created for https://bugzilla.mindrot.org/show_bug.cgi?id=2757

I have undone the patch in my OpenSSH 8.0 and ClientAlive functionality is restored to a working state.

I have tested the scenario in #2757 and it seems to work as expected on my patched OpenSSH 8.0.
I get rekey events approximately every 45 seconds and no client alive messages. SSH session remains forever.
This is the expected result from the original submitter

I suggest the original bug was possibly a confusion with "ClientAliveCountMax=0” which has been fixed recently.

I have included my revert patch. Is there anything else I need to do in order to get this fixed for OpenSSH 8.3?

regards,

  Mervyn