[Q] Newbie PPP dial up problem

[Shane Huntley]

What you are trying to do isn't so simple.  The problem is that packets 
from your hosts in the 192.168.xxx.xxx be routed on the internet as they 
aren't valid addresses outside local LAN's / private networks.  To talk 
on the internet the host needs to have or appear to have a valid IP 
address so the remote webserver can address the reply.

There are two solutions to the problem:

 Network Address Translation (NAT) wunning on your gateway computer will 
relable packets going out with it's valid internet IP address allocated 
to the ppp0 interface and redirect the replies. 
 http://netfilter.samba.org/unreliable-guides/NAT-HOWTO/NAT-HOWTO.linuxdoc.html
gives a guide for the 2.4 Kernel or a google search for "NAT LINUX" will 
turn up heaps more info.  IP-Masquerading is another term for this.

The other possible way of getting around this would be to set up your 
gateway machine as a web proxy using something like SQUID.

Personally I have cheated and have a dedicated box running "smoothwall" 
as my gateway machine "www.smoothwall.org" which takes care of just 
about everything straight out the box.

Shane


Donovan J. Edye wrote:

>G'Day All,
>
>What I want to do is so simple I cannot figure out why I cannot get it done.
>I have a gateway box 192.168.40.1. Attached to that I have a modem. I would
>like the rest of the network 192.168.40/24 to use the .1 box to access the
>net. I have set up the dial up info using pppconfig, but the routing does
>not appear to work. I can ping the 192.168.40.1 box from another machine on
>the network say 192.168.40.10 but when I tracert to say www.hp.com
><http://www.hp.com>  from the 192.168.40.10 box I do not seem to go out the
>ppp0 link. I have no firewalling whatsoever in place. Can someone please
>point me in the direction of a FAQ / HOWTO that shows how to set up a LAN /
>Dialup configuration such as the above?
>
>--D
>