I was trying to set up an Ubuntu machine to act as an Internet connection for my whole LAN, via a wireless router's Internet port. Here's how I got it working:

Equipment:
  • Ubuntu 11.04 Desktop with Ethernet port
  • Linksys WRT120N Wireless N Router
  • Huawei E620 USB Broadband Modem
  • Ethernet cable

Hardware Setup:
  • Huawei plugged into Ubuntu machine
  • Ethernet cable plugged into Ethernet port
  • other end of Ethernet cable plugged into the Internet port of The Linksys

Ubuntu Setup:
  1. connect the Huawei to the Internet
  2. disconnect the wired connection (Auto Eth0) in network tray icon
  3. create new wired connection (Edit Connections... > Add, enter a name) and select Shared To Other Computers from IPv4 settings tab.
  4. connect to this new wired connection
  5. note down the settings for this connection under Connection Information, and the DNS servers for the Huawei connection

Linksys Setup:
  1. connect a computer on the receiving side to the Linksys (wired or wireless)
  2. open a browser in this computer, navigate to Linksys (192.168.1.1 is default, user and password should be both admin)
  3. Change Internet Connection Type to Static IP
  4. Under Internet IP Address I put the number that came after the Ubuntu machine's IP address for this connection (again, not the IP for the Huawei connection), this was just a guess as I'm pretty clueless about how this works. So, my Ubuntu machine had an IP of 10.42.43.1, and I gave the Linksys [/I]10.42.43.2[/I]
  5. Subnet Mask should be same as the Ubuntu machine, 255.255.255.0
  6. Default Gateway should be the Ubuntu machine's IP address, 10.42.43.1 in my case.
  7. DNS 1 (etc.) should be the same as the Primary DNS (etc.) used by the Ubuntu machine in the Huawei connection.
  8. Click Save Settings.

That's it. Computers connected to the Linksys can now browse the Internet via the Huawei connection

Finally, after days of trying all sorts of things, I have an alternative to buying a router with a port for my USB modem. Using this method, I'm going to try to use a 1st gen. eeePC as a router instead