[gentoo-user] Disable remote login for certain user

[Grant]

One of the users set up on my router is for whoever is sitting in
front of the router and wants to log in.  For that reason, the
password needs to be simple and I'd like to prevent that user from
being able to log in if they aren't in front of the system since the
password is simple and should be easy to hack.  Should I do that via
an ssh config setting, in shorewall, or somewhere else?

- Grant