Firewall Rule Basics
Firewall rules control what traffic is allowed to enter an interface on the firewall. Once traffic is passed on the interface it enters an entry in the state table is created. A state table entry allows through subsequent packets that are part of that connection.
Firewall rules on Interface and Group tabs process traffic in the Inbound direction and are processed from the top down, stopping at the first match. Where no user-configured firewall rules match, traffic is denied. Rules on the LAN interface allowing the LAN subnet to any destination come by default. Only what is explicitly allowed via firewall rules will be passed.
Firewall rules are managed at Firewall > Rules. Multiple rules may be selected for some actions by clicking on their row or checking the box at the start of their row. Rules may be deleted or reordered in bulk in this way. See Managing Lists of Items on pfSense for more information on the meaning of the icons when manipulating rules.
On the Firewall Rules page, there is a tab for each interface, plus a tab for each active VPN type (IPsec, OpenVPN, PPTP), and a tab for Floating Rules which contains more advanced rules that apply to multiple interfaces and directions.
When editing a rule many of the options are explained in detail on the rule editor screen. Be mindful of the default settings on the rule editor, especially the protocol. New rules default to TCP only.
When entering addresses into firewall rules, the following choices are given for the source and destination addresses. Some of these options only appear in specific fields or circumstances, or if certain features are enabled.
- any - 0.0.0.0 to 255.255.255.255, or all IPv6 addresses
- Single host or alias - Select this and enter one IP address (220.127.116.11, aa:bb:cc:dd::1) or type the name of an Alias that has already been configured (Firewall > Aliases)
- Network - Select this and enter a network and mask (10.99.0.0/16, aa:bb:cc:dd::0/64)
- LAN net - The subnet configured on the LAN interface under Interfaces > LAN. On pfSense 2.2+, this also includes IP alias networks on that interface.
- LAN address - The IP address configured on the LAN interface under Interfaces > LAN
- zzz Net / zzz address - Works the same as LAN above but for other interfaces (WAN, OPT1, OPT2, etc.)
- PPTP clients - Automatically locate and use the addresses of PPTP clients
- L2TP clients - Automatically locate and use the addresses of L2TP clients
- This Firewall (self) - Any IP address assigned to any interface on this firewall (pfSense 2.2+)
These macros are handy because they allow generic rules to be created that refer to LAN or a specific interface. If that interface IP address or subnet changes in the future, the rules will be rebuilt correctly and they will not need manually adjusted.