rssh is a restricted shell for use with OpenSSH, allowing only
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. For a list of platforms on which
rssh is known to work, see the Platform Support Page.
I never remember to update this page, so go to the rssh homepage instead.