Linux: Can I hide the version that my ssh server sends
(And maybe hide that its an ssh server?)
With OpenSSH you cannot. At least without modifying the source and
recompiling or hacking the executable.
It always sends:
You can see this by doing:
$ nc localhost 22 < /dev/null
Where 22 is your ssh port
Not sending this might break some clients.
It would be nice to change the name of the product at least.
In /etc/ssh/sshd_config you can add:
And just some misleading stuff in /etc/ssh/banner.txt like
Welcome to DARPA
This is is in addition to the SSH-<version>-<comment> line. It does
not replace it.