How I Installed Wirelss To An Existing DSL

by: Warren Mudd

My wife and I live full time in our RV. Although many full timers are really more permanent residents in a fixed RV park location, we travel constantly and stay at any location no more than a month and frequently far less than that. So that means we move a lot. We don't have the money for one of those high speed "internet in your rig" dish antenna setups, so we rely on existing wireless offerings that are now available in most RV parks.

But, more often than one would wish, there either isn't any wireless offered or it's of such poor quality that it's more frustrating than it's worth to try and use it. Not only that, we occasionally camp out at either a family or friends property if they have room, and mooch off of their electricity and water, and wireless if they have it. We have our backup solution in that case, an AT&T "air card", a device that plugs into the USB port of the laptop and uses the cellular network to connect us to the internet. But what if you can't get a reliable cell phone signal?

Recently we stayed at my brother's large property on Orcas Island in Puget Sound. Not only do we not get a strong cell signal, he doesn't have any wireless at all. Thankfully he has DSL running into his house. His DSL modem is the basic model that hooks one computer via a hard Ethernet wire to his modem. I have a "box of tricks" that we brought with us, and one of those tricks is a wireless router. Actually I have 2 wireless routers that lets me build a different solution, but that's another article (see My solution was to take one of my routers (Linksys N) and configure it to use the DSL modem as its host and then to be both the hardwire host to the existing Mac and my wireless rig network.

I wanted to be able to create a temporary wireless network that piggybacked on the existing hardwire one, and that I could simply disconnect and walk away from when I was ready to move on. So I didn't want to reconfigure the existing setup. I used the Mac's "System Preferences" function to determine the IP address it was getting from the modem: (your numbers will probably be different). This told me that the modem was set up as a "192.168.1" subnet, and that it was serving the individual device IP numbers via DCHP (Dynamic Computer Host Protocol). That means the "47" part of the address was coming automatically from the modem, and all you need to do is make sure your computer (or your wireless router in this case) is using DHCP to get its address, and you are all set. So the first configuration for my wireless router was to set it to use DHCP (see your routers User Guide, you can get one online for sure). The next part is to let MY wireless router create its own subnet so I can remove the Mac from the modem and plug it into a hardwire port on the wireless router. I configured the wireless router to have a subnet of "", the "2" part sets up a separate subnet that all my wireless stuff and the Mac can now connect to. Once I got that all set, I unplugged the Mac from the modem, plugged the "uplink" port on the wireless router into the modem, plugged the Mac into a hardwire port on the wireless router, powered everybody up, and voila! The Mac, since it already was using DHCP, needed to be rebooted, but then it happily went out and got another IP address and was up and on the internet in no time!

As a footnote to gearheads that understand this stuff, my Linksys N router uses DD-WRT, the linux freeware that replaces the Cisco firmware on the router. It's much more configurable, has a great UI, and lets me control features of the router like broadcast signal strength. I jacked up the signal strength from the default of 50 to the maximum of 251 since I was parked quite a distance away, and the Mac slowed to a crawl. I backed off the signal strength to 175 and everybody was then happy. So pay attention to some of the "booster" settings (I also turned Afterburner off), or they might make some network users unhappy.