Been looking into some existant sshd implementations in go. Most of the projects on github seem to use the standard x/crypto/ssh lib.

During testing, i just wanted to see which banner these kind of ssh servers provide, using the simple command:

 nc localhost <port>

And noticed that at least some of these “sshds” did not accept any further connection. Simple DoS via netcat, nice.

Until this day, the Golang documentation is missing some crucial hint that the function handling the connection should be called as goroutine, otherwise it simply blocks any further incoming connections.

Created some pull requests on the most starred projects i found, seems even experienced golang devs missed this part.