Based on rssh package in pkgsrc-wip by pancake at phreaker dot net,
slightly modified and updated to latest version by myself.
Claim stewardship.
Rssh is a restricted shell for use with OpenSSH, allowing only scp
and/or sftp. For example, if you have a server which you only want
to allow users to copy files off of via scp, without providing
shell access, you can use rssh to do that.
