Creating a Wireless Client Bridge

I recently moved into a new apartment that included Internet service as part of the rental agreement. Of course, the landlord’s idea of included Internet amounted to my handing him my laptop while he surreptitiously typed his WEP password into my wireless connection settings in OS-X. I won’t even comment on how long it took me to open the KeyChain utility and find the key for use in my BlackBerry Bold, UMA enabled Nokia 6301 from Fido and so on, and all was well with my WiFi enabled electronics… except for one small problem…

For many years I have been a subcriber to Vonage’s VOIP service. I know there is much mixed feelings about Vonage out there, but they have served me incredibly well since I signed up in 2003. Vonage however, works though an ATA that only has an ethernet connector, so there was no way I could hook it to the landlord’s free Internet. Remembering that DD-WRT, the alternative firmware for the very common Broadcom and Atheros based WiFi routers that one can buy for about $40 – $50 at most consumer electronic stores today, can operate as a bridged client, I thought I would give it a try.

Looking through my box of electronics, I came accross a now discontinued Linksys WRT150N router that can run DD-WRT, although there is a plethora of routers that will work, including the almost ubiquitous WRT54Gx (be aware that versions above 4 have less flash memory and RAM as Cisco’s value engineers have been at them, and therefore cannot run the full featured version of DD-WRT). This router already had DD-WRT on, as I had found it was not very stable running the Linksys firmware on it, so I did not have to go through the process on installing it, however for the record, if you have this same router, installing DD-WRT is a fairly straight forward two-step process..

Once you have the router up and running DD-WRT, connect to it on the web interface using your favourite web browser, its default address is 192.168.1.1. After the first time installation the firmware will prompt you for a fresh router administrator and password, complete this and you will get to the firmware’s home screen. If you have not restored the router to factory defaults, do that now, by selecting Administration|Factory Defaults and apply and wait for the device to reboot.

Once you are back into the firmware after the reboot follow these steps to place it into client-bridging mode:

1. First, you need to set the router’s IP address to something other than the IP address of the router that you will be connecting to, however you want to make sure that it is still on the same segment.  In my case, the landlord’s router is at 192.168.0.1/24, so I just made the WRT150N sit at 192.168.0.2/24, since most wireless routers don’t assign DHCP addresses that are directly beside their own IPs.  If you do not have access to the configuration of the AP router, I would suggest that you at the very least ping the address you want to use and make sure that there is nothing on it.  To assign the new IP, go to Set-Up|Basic Setup, and enter the IP you have selected, and check the box for “Assign WAN port to switch”.  Now click “Save Settings”, which will write the changes on this screen to the NVRAM but not apply them.
2. Now go to Security Settings, and disable the SPI firewall in the router, and again click “Save Settings”
3. Next, bounce over to Basic Wireless Settings, and select “Client Bridge” as the operating mode, enter the SSID and Channel number of the AP you wish to connect to into SSID and Channel Number, click “bridged” for Network Configuration.  Again, save your settings.
4. Now head over to Security Settings, and fill in the authentication parameters of your primary router (the one you want to connect to) and press save.
5. Lastly, check in Admin|Wireless Site Survey and make sure that your primary router is listed.

Having accomplished all that, reboot the client router, and it will connect to the parent router.  At this point, I simply plugged my Vonage ATA into one of the switchports on the back of the client router using an Ethernet cable, and I could use my phone again…

If anybody is interested, I will add some screen grabs of the configuration to this post.

Tagged as: Client Bridge, DD-WRT, Firmware, Linksys, Tomato, WRT150N, WRT54G