As of Plesk 12, both Linux Virtual Servers and Windows Virtual Servers have Firewall management support built in.

To manage the Firewall rules:

1. Login to your Plesk control panel.
2. Go to the “Tools & Settings” option under “Server Management”.
3. Click on “Firewall” under the “Security” section.
4. To modify rules, click on the “Modify Plesk Firewall Rules” button.
5. The list of existing rules will be displayed.
6. Click on a rule name to modify it or “Add Custom Rule” to create a new rule
7. Once you’re done updating your rules, click the “Apply Changes” button

If the Firewall isn’t installed, visit the “How do I install new components in Plesk” FAQ for instructions on installing it.