Subject: Re: Interface specification in route(8)
To: Guenther Grau <>
From: Lucio de Re <>
List: tech-net
Date: 02/23/1999 05:51:28
According to Guenther Grau:
> IP-routing is based on the network part of an ip-address. As you have
> two
> interfaces which are in the same ip-network, I doubt routing will work
> properly. I see two easy solutions to you problem. 
I assumed, as quoted in an earlier message, that the -ifp or -ifa 
qualifiers to route(8) could be used to discriminate where nothing else 
does (KA9Q allowed that, so it should be possible, although changes to 
*BSD kernels may be extensive).  As mentioned elsewhere, that bit of 
documentation could do with some clarification.

> 1) Use a different IP-net on the ppp-link. You can use NAT on the
> NetBSD machine to translate incoming ppp-packets to have a proper
> IP address if you need to.
I can do that, nothing like and to solve these 
problems, but I would prefer the ability to use unnumbered links.  I 
must look into this, I'm getting more comfortable with my understanding.

> 2) Create a small subnet in the 192.168.30 net, which contains only
> two IP-addresses and use these for the two hosts doing ppp.
> is already too small, removing 4 entries from it would 
be a bit much :-)  But you're perfectly correct, of course.

> traceroute accepts an interface on the commandline. man traceroute.
Yes, but someone on this list produced a patch that used the routing 
tables to determine the path packets would follow to a particular host 
(in my particular case "default" goes through "ppp0" whereas 
traceroute(8) insists in using ne0) and that's what I would dearly like 
not to have to re-invent.

> > PS: seems I'm having trouble resubscribing to tech-net, so if you see
> > this you might have to reply off the list to get to me :-(
> What's the problem? You can either do it via email to
> with subsbribe tech-net in the BODY
> of the mail or just go to and click your
> way trough to the mailing lists. There you'll find a 
> subscribe button.
I assumed would work in the conventional 
manner, and access to the subscription portion of the web site 
continued to time out and return a connection dropped.  I have since 
resubscribed, thanks.