Blocking IP... How to


Can anyone tell me how to block a specific IP? I'm thinking I should use the Firewall in System Preferences but I'm ignorant of the workings of firewalls. Any help would be appreciated.
For what purpose? More information on what you want to achive exactly would be quite helpful un developing a solution for your problen :)
A close aqcuantance of mine has access to my sweet Mac and I'd rather just deny them any communication with my machine then change all my passwords and user accounts.
Change your password. Even if you do block their IP, there would be nothing to stop them going to another computer and trying from that. Also, your acquaitance's IP address may change from logon to logon.

You could use ipfw (IP Firewall) from the terminal to block a specific IP address, but this would not be the ideal solution. If you want to know a bit more, type "man ipfw" from a terminal window to bring up the manual page for the firewall.
If he has access to your Mac WITH your password, I'd change it rather sooner than later. Like mentioned above, he could just go to another computer and work from there, or have a dynamic IP adress from startup to startup