Router IP

I have a gnet ip0006 router that I need to program and I do not know what the ip address of the router is. Is there any way I can find out what the ip of the router is. Is there a program that will ping all ip addresses until it reaches one that responds (computer not connected to the internet of course). Also I need the software to setup a computer to print to the router (it has a lpt and com port) if anyone has that that would be great... If not my searching will continue. Thanks in advanced. (If you are wondering I have none of the original boxes, books, or cd's that came with it... someone lost them...)