PortsLock

PortsLock is a personal firewall for Windows NT/2000/XP that fully supports user-level security. Once PortsLock is installed, administrators can control which users can access what TCP/IP based protocols (HTTP, FTP, SMTP, POP3, Telnet, etc.) on a local computer, depending on the time of day and day of the week.

PortsLock lets you set allowed/denied TCP/UDP ports and IP-addresses for incoming and outgoing connections.
Keep in mind that almost 80% of all security breaches come from the inside! PortsLock is an easy-to-use security solution that fully protects corporate networks against attacks from the inside.