Wireless bridge question

Factual Questions
1

We recently hooked up 2 of these guys to form a wireless bridge (not access point) from our wired network in one building to a wired network in another building about 300 feet away: ENCORE ENRXWI-G 802.11b/g Wireless LAN Extender up to 54Mbps - Newegg.com

Other than only running about 20 megabits when they’re supposedly capable of 54 megabits (of course that’s a problem in general with both wireless and wired network speed ratings), they work great and were easy to set up. I set them up in bridge (WDS) mode by entering the MAC address of each box in the other’s configuration, and the bridge just works. No fussing with other settings or IPs.

My question is about security though. I don’t want to use encryption because of the overhead and extra complexity. Since I’m in WDS mode am I safe from needing encryption? Will these boxes communicate with any other networking equipment that doesn’t match one or the other MAC address? I ran NetStumbler on my laptop and it didn’t find anything.

2

I think an advantage of wireless bridges is that they can apply various proprietary security measures as long as the wired outputs conform to standards, making them very secure. But this is only the impression I got a couple years ago from setting one up.

3

MAC addresses are ridiculously easy to spoof anyway, so I don’t think it would be a good idea to rely on that for security.

4

So someone could sniff wireless traffic to get the MAC addresses involved, then impersonate one of those addresses?

5

Yes - all they’d have to do is passively listen to a few packets and they would be able to determine the MAC address of the broadcasting device, then impersonate it.