My sshd is configured to accept only public key authentication and my ISP router forwards the port 22 to my MacPro so I can access it from anywhere using Internet.
This has worked for years.
Since I’ve upgraded to Big Sur, this works once I activate the Remote Login in System Preferences but after a while, the connection fails.
Once this is the case, I cannot connect using ssh even from another machine on the same LAN. The other services work fine.
If I stop the port forwarding, this does not occur.
So I installed openssh using homebrew, ran their sshd on the port 23.
Then I changed my port forwarding on the router to target homebrew openssh: extern port 22 -> macpro port 23
Same thing: after a while, it stops accepting connections with no information in the level 3 debug logs.
Of course, Apple’s own sshd continues to work.
So it seems that the failed attempt to connect to my sshd from hackers all around the world end up saturating some kernel buffer or something and only since Big Sur (currently running 12.2.2).
Does anybody else has this problem? And maybe a solution?