I have setup my PC at work with a Linksy router configured as a client bridge and an outside antenna. I'm using it to tap into the cities public wifi system. My employer has thier network Gestopo troops periodically check for unauthorized wireless networks. I'm wondering if they can sniff my setup. Any opinions or suggestions are appreciated.
Any particular model number Linksys router? Stock firmware or one of the Linux based alternatives?
Tap? Do you have permission or is this some form of wireless wiretap?
Well, you didn't describe how your work desktop is connected to the wireless client bridge and/or the office network. If you unplug from the office LAN, and plug the PC's ethernet port into the wireless client bridge, then there's nothing your employer can do on their wired LAN to find your wireless client bridge. You're literally isolated.
If your employer has a wireless system, they could find your wireless client bridge. Some wireless access points have a sniffer feature, that searches for other wireless traffic. A few will do direction finding by time difference of arrival.
However, if you're simultaneously connected to the office LAN and the wireless client bridge, through a switch, hub, or dual ethernet port, you're going to get caught by ARPwatch. It looks for new devices on the network. If your wireless bridge MAC address appears on the office network, it will show up as a foreign device. There are similar tools for wireless, but most admins only monitor their own network and probably do not monitor or log the municipal WLAN traffic.
Please do your best to avoid detection and keep your job. I wouldn't want you working for me.