I've seen many tools to use Ubuntu as a router in which an internet connection could be shared from Ethernet over Wifi or vice versa. I'm looking to achieve this except with 2 Ethernet connections:
Internet --> Computer 1 (with 2 Ethernet cards) --> Computer 2
How can I configure Computer 1 to be able to share the connection in the above method. I'm confident in using the terminal or editing config files, but I would much prefer some sort of automated GUI based program such as the settings available in OS X.
I cannot just use a router, I don't have a spare router to use for this temporary set up that I need. I can use any KDE, Gnome or XFCE based tool.