Jul 15 2009
Making a Wireless Router Act Like an Access Point
***Warning*** this post is pretty geeky. I wrote it so I might refer back to it if needed, and also if someone has a similar problem they are trying to solve. (If my students see my awesomeness in the process, that is another acceptable outcome 
I got to blow the dust off of my networking skills a little bit today. I teach an introductory networking course and I used to be a system administrator/networking pro, but honestly my skills get a little rusty if I don’t put them to the test once in a while.
Sometimes my networking students wonder why I make them do labs where they must manually configure all of the TCP/IP settings when DHCP will do it automatically. Without knowledge of how to set things up manually, I would have been unable to solve a real-world problem today.
What I thought would take me an hour wound up taking nearly 3. Terry, down at the hardware store, asked me to hook his laptop up to his store’s network using wireless. Terry’s always so willing to help out Wendy & me with stuff that goes wrong around our home (most recently it was the lawn sprinker system), I was hardly in a position to refuse. I had already taken the day off for jury duty and I didn’t know when I would have time otherwise, so I agreed to look at it this afternoon.
The first hour was spent just figuring out what he had, and learning circuitously that the wireless router wasn’t configured & working as expected. (Hmm, I might have thought to ask about that part up front!) He could always get the Internet to work through the wireless, but he couldn’t see the store server, where his merchant programs & data reside.
He already had a router connected to the DSL, and this wireless router was really overkill. All he needed was a simple wireless access point. And that was what I struggled with for quite a bit longer than I should have. The router created a separate network, and was preventing access to the store network through it. How could I make the router act like an access point?
My final solution was to configure the wireless router in this simple manner:
- Set the WAN side to Autoconfigure with DHCP and leave it disconnected.
- Configure and connect the LAN side to the store network.
- Configure the laptop with a static IP also on the store network.
- Enable security settings.
Setting things up this way, we bypassed the routing part, only utilizing it as a wireless access point. I spent a lot of time looking for settings in the D-link router config to try to disable routing, but found no such option. Once I figured out that I could get away with hooking up only the LAN side of the router, and the laptop would still talk to it, I was set. Initially, I tried letting the laptop use the router’s DHCP, but when I did this, the laptop was configured to think that the wireless router (which wasn’t connected on the WAN side) was the gateway to the Internet, so the Internet wouldn’t work. The workaround was to use a manually configured IP with the correct gateway address.
It took a lot longer than it would have back in my glory days of networking, to be sure, but it’s good to know that once the cobwebs are blown out, I can still solve real-world networking problems from time to time. I never wanted to be one of those “theory only” professors anyhow. Hopefully doing little projects like this will ensure that I am always able to function in the real world as well as in classroom or laboratory.
