Gateways

Gateways are the key to routing; They are systems through which other networks can be reached. The kind of gateway most people are familiar with is a default gateway, which is the router through which a system will connect to the Internet or any other networks it doesn’t have a more specific route to reach. Gateways are also used for static routing, where other networks must be reached via specific local routers. On most normal networks, gateways always reside in the same subnet as one of the interfaces on a system. For example, if a firewall has an IP address of 192.168.22.5/24, then a gateway to another network would have to be somewhere inside of 192.168.22.x if the other network is reachable through that interface. One notable exception to this is point-to- point interfaces like those used in PPP-based protocols, which often have gateway IP addresses in another subnet because they are not used in the same way.

Gateway Address Families (IPv4 and IPv6)

When working with routing and gateways, the functionality and procedures are the same for both IPv4 and IPv6 addresses, however all of the addresses for a given route must involve addresses of the same family. For example, an IPv6 network must be routed using an IPv6 gateway/router. A route cannot be created for an IPv6 network using an IPv4 gateway address. When working with gateway groups, the same restriction applies; All gateways in a gateway group must be of the same address family.

Managing Gateways

Before a gateway can be utilized for any purpose, it must be added to the firewall configuration.

If a gateway will be used for a WAN-type interface, it can be added on the configuration page for that interface (See Interface Configuration Basics), or it may be added first manually and then selected from the drop-down list on the interface configuration.

Dynamic interface types such as DHCP and PPPoE receive an automatic gateway that is noted as Dynamic in the gateway list. The parameters for such gateways can be adjusted the same as the parameters for a static gateway, but a dynamic gateway may not be deleted.

To add or manage gateways:

  • Navigate to System > Routing
  • Click the Gateways tab
  • Click fa-plus Add at the top or bottom of the list to create a new gateway
  • Click fa-pencil next to an entry to edit an existing gateway
  • Click fa-trash next to an entry to delete a gateway
  • Click fa-ban to disable an active gateway
  • Click fa-check-square-o to enable a disabled gateway

The individual options for gateways are discussed in detail in the next section.