Setting up routing to share a modem

[Stuart Ballard <sballard@netreach.net>]

Hi,

I'm looking to set up my debian box as a router to share the modem
between itself and another machine which is dual-boot (debian/win98).
Since I work at an ISP I can get a static IP for the second box as well
as the first (when I dial up the radius server at my ISP recognizes my
username and assigns the right IP). I would like to be able to share the
modem when both computers are on, but have the dual-boot box able to
dial up by itself also.

I know that to do this I have to recompile my kernel to enable IP
forwarding, but beyond that I have no idea how to make this work. Do I
need to turn on any other features in the kernel? How do I configure the
dual-boot box to enable it to recognize this route, but still be able to
work through dialup? And what do I need to ask the networking guy at my
ISP to configure, routewise?

Thanks in advance,
Stuart.