Limiting users who have shell access to use a certain ip

[davidr@skyforge]

hi
    does any one know a way of being able to limit a group/all users who has
shell account to a freebsd server to use a certain ip address when they
tried to connect to the internet ? Is what i am saying even possible ? or
would  I need a big cisco type router to do such a task
--
David Richards
davidr AT skyforge DOT net
http://www.skyforge.net