How do I turn my DD-WRT router in to an access point?

Question

I have a n-based router from Linksys with DD-WRT installed. I would like to turn this in to an access point because I already have a router/firewall installed on my network.

Answer 1

You need to:

1. set up the wireless interface
2. start serving DHCP out over the wireless interface

and then you're mostly done. Note that while step 2 is fairly straightforward using dnsmasq, the difficult of step 1 can vary from 'trivial' to 'you need to reverse engineer the wireless drivers'. Giving you more instructions at the moment requires more info (model number & rev) of the Linksys router in question. There's a DD-WRT table of supported hardware that can probably help you.

Oh, and all this is presuming that your definition of 'access point' is something like 'a way to connect a machine with a wireless ethernet card to the network' as opposed to some kind of walled garden setup.

Since you indicate you've got a router, you also may want 'bridge mode' where the wireless network is 'bridged' to the wired network and they share an IP range. This page has full details on how to do that.

Answer 2

The trick is to make sure DHCP is turned OFF in the router/access point so that your wireless clients get IPs from your existing router/firewall.

There are more details on the DD-WRT wiki but the main idea is that you set the WAN to "Disabled", Disable DHCP, and plug the AP into your network using one of the LAN ports instead of the WAN port (or use the "Assign WAN Port to Switch" feature).

You can actually do this with basically any Wireless router without DD-WRT using the same basic steps (disable DHCP, plug into LAN instead of WAN).