How do I implement Secure Socket Shell (SSH)? Through a firewall? Client required? On Unix? NT?
There are two pieces to SSH. One is the SSH server and the other is the SSH Client. For most versions of Unix, you can get SSH server software and installation instructions from http://www.openssh.org.
For Windows NT, I don't know of any open-source version. Commercial versions are available from http://www.ssh.com and http://www.datafellows.com/products/ssh/server/. There may also be others. Note that these are commercial products, so I'm sure they can assist with installation.
For the client side, there are many choices and http://www.openssh.org has links to where you can find them. Installation of the clients is different for each, and you'll have to look at the instructions that come with each package. The commercial firms noted above also have client software.
I use SSH through a firewall with no problem. Obviously, the firewall must allow the connection. The firewall I pass through allows most everything out, and allows anything in that was requested by a host inside the firewall. It uses what is known as "statefull inspection" to track this. (Please see an earlier question I answered about firewalls for more info on statefull inspection.)
I doubt you'll have much problem getting through a firewall. If you do, explain to your firewall security admin what you are trying to accomplish, that is provide more security than plaintext telnet, and they'll likely work with you.