Well, I have spent the last two weekends trying to set up a lab at home to retest the tutorials for the http://www.linuxhomenetworking.com website. I put it in the garage but needed the test servers on the lab’s switch to connect to my wireless network whose WAP/Router is in my bedroom.
I thought of doing this some years ago, so I bought a Linksys WGA54G game adapter that allows you to connect your Playstation’s ethernet port to your WLAN. I decided to attach the switch to it instead, so that in its “infrastructure mode” I could provide WLAN access to all the lab servers.
Well, I soon discovered that it bridges at layer 3, but at layer 2 it is a little different. The MAC address of all the servers are re-written with a MAC assigned by the WGA54G. This is OK, but the MAC it uses is always that of one of the servers it discovers on its ethernet port. It presents this MAC on both the WLAN side and the wired side. When you try to connect to another server on the wired side the packet gets sent to the server whose MAC address it cloned, not that of the server to which you really need to connect.
I wondered whether putting a single IP address behind it would fix the problem, so I put a DSL router behind it to NAT the traffic from the switch to the WGA54G. I then used port forwarding to get access to the lab servers. Same problem. This makes me wonder whether it also sends traffic on to the LAN using a single source MAC address, not its own, but that of the first MAC address it sees on the WLAN. This is OK for a Playstation, as I assume it only wants to talk to the web, and the first packet it receives will always come from the home router / DHCP server. But in my case the servers were communicating with the internet and my personal WiFi laptop.
I now have purchased a Linksys WET54G on Craigslist for the price of a half dozen submarine sandwiches, and in “infrastructure mode” using MAC cloning, and a fictitious MAC address, everything works fine. It seems to have memory allocated to mapping the rewriting of the source and destination MAC addresses as traffic passes from the WLAN to the LAN.
The cost difference for this extra RAM to store more than 2 MAC addresses? A new WGA54G costs $129 and the WET54G costs $99. The replacement model Linksys WET200G costs $125 list.
My question is why does a device with more functionality cost less? Maybe because they can make more money selling low cost hardware to price insensitive gamers for a small fortune.
Note: If you have a WET54G version 3.1, the version v2.15 firmware of Jun 11, 2007 is notoriously buggy with the WET54G hanging up frequently. Downgrade to firmware version v2.07, Jun 30, 2006 for the version 3.0 WET54G and you should have no problems.
