PC-BSD uses the PF firewall to protect your system. By default, the firewall is configured to let your system make Internet connections, use the ping utility, and to communicate with other Windows and Unix-like systems.
Advanced users who are already familiar with pf will find the default rulebase in /etc/pf.conf. Users who aren't familiar with directly editing this file can instead use the Firewall Manager GUI utility to view and modify the existing firewall rules.
Note: typically it is not necessary to change the firewall rules. If you disable the firewall or remove the nat rule, ports jail will cease to work. You should not remove any existing rules unless you fully understand what the rule does. Similarly, you should only add rules if you understand the security implications of doing so, especially if the rule allows connections to your computer.
To access the Firewall Manager, go to Application Launcher -> System Settings -> Firewall. Figure 7.1a shows the initial screen when you launch this utility:
Figure 7.1a: Firewall Manager Utility
The General Settings tab of this utility allows you to:
- determine whether or not the firewall starts when the system boots; unless you have a reason to do so and understand the security implications, this box should remain checked so that your system is protected by the firewall
- start, stop, or restart the firewall: if you add, delete, or modify a firewall rule, you should restart the firewall for your changes to take effect
- restore default configuration: this button allows you to return to the original, working configuration should you not like the changes you make to your firewall rules
To view or modify the firewall rules, click on the Exceptions tab, seen in Figure 7.1b:
Figure 7.1b: Adding a New Firewall Rule
In this example, the user has clicked on the "Add entry" button to add a new firewall rule. The following information is needed when creating a rule:
- service or port number: you can either select the name of the service you wish to allow or block from the drop down menu or type in the number of the port used by the service. Which you choose does not matter as the firewall will match the name and number for you and display both after you save the rule.
- policy: you need to choose whether to allow or block this service/port
- direction: use the drop down menu to determine whether the policy applies to incoming or outgoing connections; the direction is from the perspective of your computer i.e. do you want others to connect to your service (incoming) or do you want to connect the service running on another system (outgoing)
- protocol: use the drop down menu to select whether the service uses the TCP or UDP protocol
- interface: use the drop down menu to select the interface that will make or receive the connection