So, I have a wireless connection and I want to setup my linux box to share it with my LAN.

Sounds straight-forward, and I'd have no problem doing this setting up my router with DD-WRT as a bridge. However, the WiFi connection is an ad-hoc network using ICS through my Windows Mobile Verizon phone and the router won't connect to it.

That said, Linux connects to it just fine. So I have a small low-power-usage PC I'd like to use to create this bridge... So of course first I connect Linux to my ad-hoc network. SO, the real question is: How do I set Ubuntu to share that connection with the ethernet card?

Yes there are a bunch of guides out there for sharing connections, but they all go from wired to wired or wired to wireless, not wireless to wired. If the process is the same, and ad-hoc ICS on the phone won't affect it any, then let me know. Otherwise, I'm going to need some help to set this up.

Other possible problem: I have a WiFi router I use to serve IP addresses to my LAN. I wouldn't mind setting up the Ubuntu box to do DHCP and DNS for the I-net, but I wanted to mention this potential snag.

Finally: I do NOT want to connect all PC to the ad-hoc net on the phone, cause the phone is't always around, and the PC still need the LAN when the I-net is gone.

Why do I use the phone for I-net: cause no other high-speed is available.