the server (???)

sshd from cygwin should to the trick, like one of the many other SSH server implementations for Win32.

Sometimes, a friendly Linux or *BSD machine near the server can also help, running the ssh server, tunnelling a port to the windows server. In PuTTY, specify windowsbox.remote.lan:1433 (not localhost) as tunnel destination when connecting to linuxbox.remote.lan. It may look strange, but it works (unless linuxbox and windowsbox are separated from each other by a firewall). With the openssh command line client, it should look something like this:

Connect to localhost:1433 and you should see the SQL server as long as the ssh connection is alive. The command line for PuTTYs plink utility should look nearly the same.

Alexander