Subject: Re: PPPd's selection of interfaces
To: Lucio de Re <>
From: Dr. Bill Studenmund <>
List: tech-userlevel
Date: 09/21/1998 11:24:56
On Mon, 21 Sep 1998, Lucio de Re wrote:

> 'Scuse the multiple posting, I'm not sure which list is more 
> appropriate.
> It took me a while to figure what had seemingly gone wrong with NAT and 
> filtering on a client site, although it had been staring me in the 
> face: on startup two "pppd" instances had somehow reversed positions 
> and the nett result was that a site intended to be within the network 
> found strict filtering rules applied to it, while the rest of the 
> Internet was granted the type of access I permitted such sites as are 
> intended to be "within" the network.

You might look into the ipup (or ip-up) script. It is passed a lot of
parameters when inet gets fired up on a ppp interface, such as which ppp
interface this is, and the IP address. If your filtering can be turned on
and off in the ip-up and ip-down scripts, you should be fine. Just have it
decide if it's dealing w/ the rest-of-net interface, and do the rules iff
you're on that interface.

Take care,