How do I open ports on my airport extreme and assign a fixed IP Address for a device connected to my network?

Your home Router will give out automatic IP addresses using DHCP by default, starting at the number one more than the Router's address, and continuing up the range. You can use one of these approaches to avoid address collisions:

a) Give out a higher number that seems like it will never be reached by DHCP. Example, if the Router is at 192.168.0.1, give your alarm 192.168.0.250 (but stay away from 254 and higher).

b) Give out the low numbers, and change the configuration to start giving out DHCP Addresses much higher. example if the Router is at 192.168.0.1, start the DHCP Addresses at 192.168.0.50, and give your alarm 192.168.0.10.

In either case: You need to tell the alarm its Manual IP address. Then you need to use Router Port Forwarding to forward incoming requests for that port ( :80, you said?) to the address of the alarm (whichever you choose).

From the outside world, you connect to the externally-visible IP Address of your home Router (provided by your ISP) using the browser (specifying port :80) or other Application they provide, and it should forward to the alarm and connect. If your externally-visible IP Address changes, you will have to note the change and adjust the IP Address.

If this is just "word-salad" to you, please post back for more details.

EDIT: your alarm installer is an idiot -- this is not Mac-specific in any way. He needs more training.

There are three ranges of "strictly local" IP addresses reserved for local Network use:

192.168.xxx.yyy

172.16.xxx.yyy

10.xxx.yyy.zzz

What your Router does for you is to act as your agent on the Internet.Your requests are packaged up and forwarded on your behalf, and only when a response is expected is the response returned to your local IP address.

Directing Network Traffic to a Specific Computer on Your

Network (Port Mapping)

AirPort Extreme uses Network Address Translation (NAT) to share a single IP address with the computers that join the AirPort Extreme network. To provide Internet access to several computers with one IP address, NAT assigns private IP addresses to each computer on the AirPort Extreme network, and then matches these addresses with port numbers. The wireless device creates a port-to-private IP address table entry when a computer on your AirPort (private) network sends a request for information to the Internet.

If you’re using a web, AppleShare, or FTP server on your AirPort Extreme network, other computers initiate communication with your server. Because the Apple wireless device has no table entries for these requests, it has no way of directing the information to the appropriate computer on your AirPort network.

To ensure that requests are properly routed to your web, AppleShare, or FTP server, you need to establish a permanent IP address for your server and provide inbound port mapping information to your Apple wireless device.

To set up inbound port mapping:

1) Open AirPort Utility, select your wireless device, and then choose Base Station > Manual Setup, or double-click the device icon to open its configuration in a separate window. Enter the password if necessary.

2) Click the Advanced button, and then click Port Mapping.

3) Click the Add ➕ button and choose a service, such as Personal File Sharing, from the Service pop-up menu.

Please check out the following AirPort User Tip for details on how to use the AirPort Utility to configure port mapping on your AirPort base station.

If you are using AE with version 6.1 firmware, none of this works anymore. Apple ripped out these great features.

BUT... I am now struggling to open specific ports on my AE and cannot figure out how to do it without rolling back about 4 revs.

If you are using AE with version 6.1 firmware, none of this works anymore. Apple ripped out these great features.

Suggest that you look a bit deeper. Everything is there in AirPort Utility 6.1....assuming that you have the AirPort configured in router modem, not bridge mode: