Lots of firewalls do that. Ipcop (freeware) will do it although it is
a bit of a PITA to maintain - the restriction, that is. Ipcop itself
is fire and forget.
For Windows 2000/XP Pro/2003 you can use ipsec policies using either filtering with
permit and deny rules or negotiation with AH/ESP to control access by computer IP
address. Domain controllers can not use ipsec negotiation policies with domain member
computers however. See the links below for more info. --- Steve
