IPShutter lets you firewall off ports such as ssh,
and selectively enable access with a one-time
password. For example, if you want to log into the
server from a friend's house, you pull out a list
of one-time passwords and point the Web browser at
a URL that contains one password. That tells the
server to allow ssh connections from your friend's
IP address for five minutes. Connections made in
that period will stay up indefinitely.
