Apple Airport Extreme “disable” DHCP and keep NAT

The Apple Airport Extreme is my home router and access point. Recently I wanted to use DHCP on my Synology NAS and disable it on the Airport Extreme. Guess what, when you disable DHCP on the Airport Extreme, it also disables NAT! Not what I had in mind. I am a fan of Apple products, and wanted to keep using the Airport Extreme for my WAN -> LAN connection (internet), because I am pleased with the performance and stability.

There are only three options to choose from:

  • DHCP and NAT (which I am using currently)
  • DHCP only
  • Off (Bridge Mode)

See the screenshot below:

airport_extreme_dhcp_01

None of the options suited my needs, so what I found out is that I can keep the DHCP and NAT option enabled, but deplete the DHCP servers IP address scope. So basically I am going to setup my DHCP server on the Airport Extreme with a scope of two IP addresses and then immediately reserve those ip’s with fake MAC addresses. This way the Airport Extreme will not be able to serve IP addresses in my network, and I can now setup another DHCP server to fit my needs. In another post I will explain why I need another DHCP server.

Let me walk you trough the procedure using the screenshots below.

First let’s start by opening the Airport Utility, select your Airport Extreme Base Station and click on Edit:

airport_extreme_dhcp_02

Then go to the Networking Tab and click on Network Options…:

airport_extreme_dhcp_03

Setup the DHCP scope according to the settings in the screenshot below. The IP address space on my LAN is 192.168.1.x. You can have another range, adjust it to your needs. So I basically setup a DHCP scope consisting of two IP addresses. When you’re done, click on Save.

airport_extreme_dhcp_04

Now we have to add the fake IP reservations. In the DHCP Reservations section click on the + sign.

airport_extreme_dhcp_05

I then add Dummy 1 and Dummy 2 clients using a fake MAC address. Click on Save

airport_extreme_dhcp_06

airport_extreme_dhcp_08

Now your Network tab should look something like this:

airport_extreme_dhcp_07

Click on Update and that’s it! DHCP is now “turned off” on the Airport Extreme, and you are free to use another DHCP server for more flexibility in your LAN.

 

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Vikash works as a technical consultant for a system integrator in the Netherlands, with over 10 years experience in application and desktop delivery. Virtualization is his passion, and his main focus is design and implementation of Cloud and hybrid environments using Citrix and Microsoft solutions. In addition he has broad interest and knowledge in XenMobile and VMware based solutions.