Subject: Re: dialup server (pppd)
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: current-users
Date: 02/17/2000 03:35:03
> The ppp interfaces need to have distinct ip addresses, different than
> any other ip addresses on either LAN. IP numbers are for interfaces,
> not machines.  You're telling the server to use the same IP number
> for ppp0 as for the ethernet IF, and it won't work.

It's worked fine for me in the past, and apparently it's supposed to
work (witness the way pppd defaults the IP for its end of the
connection, which wouldn't've been done if it couldn't be expected to
work).  I'm not running any ppp links this way at the moment, but I've
got two other point-to-point links set up that way (with the local end
having the same address as the machine's LAN address) and it works.

> Even if it could work, you wouldn't have any way to specify the
> routes.

Huh?  You specify routes by naming the other end of the link.  If you
have machines a.b.c.d and w.x.y.z doing ppp to one another (let's
suppose for the sake of simplicity that they're both /24 on their
LANs), then

abcd# route add -net w.x.y.0 -netmask w.x.y.z

wxyz# route add -net a.b.c.0 -netmask a.b.c.d

Note that the next-hop gateway disambiguates: if (for abcd) it's on
a.b.c.0/24, it's out the LAN; if w.x.y.z, out ppp0; anything else is an
error (unless there's some other interface that can directly reach the
next-hop gateway address given, of course).

> I echo'ed Miles suggestion that you set up the ppp link as a
> completely seperate network, and set up routes accordingly.

It seems to me that if this is the only way to make it work, something
is severely broken.

Not that it's not a useful thing to do to try to figure out what's
going wrong...and (I forget the OS rev) if the software you're dealing
with *is* broken that way, it may be the only way to make it work.  But
it's a workaround for brokenness, not the correct way to do it.

					der Mouse

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