Setup - Access Control
In the Access Control menu, you can choose either timed access based on MAC address, or enable RADIUS authentication, which requires an external RADIUS authentication server.
The Internet menu is a bit of a misnomer, as this menu tree lets you configure both your WAN and LAN connections.
Internet Connection lets you set up how you connect to the Internet. You can choose either Ethernet (with static or dynamic IP) or PPPoE.
Figure 11: Configuration of Internet Connection
The AirPort Extreme has an interesting option under the Connection Sharing menu. In addition to the traditional sharing of a public IP address, this configuration also lets you disable routing functions, effectively converting the AirPort into an access point, as well as distribute a range of public IP addresses that may have been assigned to you by your ISP.
Figure 12: Connection Sharing Configuration
Setup - DHCP
The DHCP menu lets you set the DHCP range of addresses, the DHCP lease time (default—4 hours) define an LDAP server, and set up DHCP reservations. Though you can set up DHCP reservations, it’s more difficult to do, as you have to set it up manually. You can’t choose from a list of clients to populate your DHCP reservation table like you can with other routers such as the D-Link DIR655.
It’s interesting to note that this tab is also where you define your LAN address. You have a drop-down box of the three non-routable IP subnets—i.e., 10.0.0.0, 192.168.0.0, and 172.16.0.0. You don’t have any control over the subnet mask—they are all "/24s" (255.255.255.0), and the base station assigns itself the first address in the range.
Figure 13: DHCP Configuration
In the NAT submenu, you can enable a default host that’s exposed to the Internet (i.e., DMZ), as well as enable NAT Port Mapping Protocol. Apple’s help screen indicates that NAT-PMP is an alternative to UPnP that’s implemented in many other routers.
There is also a tab for configuring port mappings. Clicking on that tab takes you to the advanced menu and the port mapping submenu. I found it interesting that the AirPort Extreme doesn’t support port triggering, which is important to online gamers. With port triggering, an outbound packet on a "trigger" port automatically opens pre-defined inbound ports used by a particular application.