internet connection sharing over ethernet

[Lennart Sorensen]

On Thu, Sep 29, 2005 at 02:26:45PM -0400, Steve wrote:
> I've got a strange question about ethernet in Linux (Ubuntu Debian). I
> want to know what sort of modifications I need to do to perform the
> following 2 scenarios (and switch between them occasionally):
> 
> 1. Current setup (currently working): Linux machine: connected to
> internet via modem + sharing internet connection over ethernet +
> running samba server sharing directories --->crossover LAN cable--->
> winxp client machine.
> 
> 2. Alternate setup (have not tried this yet): Linux machine: connected
> to internet via ethernet + running sambe server sharing directories
> <---crossover LAN cable<--- winxp machine connected to internet.
> 
> I hope that makes sense. Basically now I connect to internet on the
> linux machine and that conenction is shared over the ethernet to the
> winxp client. I want to have the ability to use the winxp machine's
> internet connection to share to the linux machine over the ethernet
> sometimes (basically the reverse of the previous). My question is that
> I have never connected to the net on the linux machine over the
> ethernet. Will it automatically detect the connection? Do I need to
> manually change IP setting on the ethernet port? Also, I'm running
> Firestarter now as my firewall and wish to run it no matter where the
> internet connection is... will it be automatic or do I need to
> manually change some things?
> 
> Thanks for any help... I was planning on just trying it out and
> experimenting, but if anyone has any pointers that would help a lot
> before I start!

Well you will have to at least change the default gateway setting on the
linux system when you change since you can only have one.  When a ppp
link comes up it adds a default route over the ppp link.  If you want to
connect through windows, you have to add a default route to the windows
machine for the ethernet, and then remove it again before you can use
the ppp link.  Rather a pain I would think.  You could always make a
script for ppp that deletes the ethernet gateway when it connects and re
adds it when it disconnects using ip-up/ip-down scripts for ppp.  Then
it might not be too much work.

As for what the windows machine would have to do I have no idea.  I
don't believe windows machiens are allowed direct links to the internet.
They must be behind a none windows based firewall with a non routeable
ip. :)

Lennart Sorensen
--
The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml