Re: [SLUG] Routing across ethernet and ppp?

[DaZZa <dazza@nospam.zip.com.au>]

On Tue, 2 May 2000, erich wrote:

> > Without knowing your subnet masking {but assuming a standard class C mask
> > of 255.255.255.0}, you have a single machine with two IP addresses on the
> > same subnet but different interfaces. From memory, this will completely
> > screw routing. The box won't know which interface to throw packets for the
> > subnet out on.
> 
> I then have a question, could the following setup work? ( I am not
> syaing it is the best) 
> 
> Machine 1: internet gateway
> 	PPP0:  	139.x.x.x, 	netmask ?
> 	eth0:	203.x.x.1	netmask 255.255.255.0
> default route GW = 139.x.x.x ppp0
> route add net 192.168.0.0 eht0
> route add net 203.x.x.0 eht0
> 
> which gets connected to the local hub. 

Nope. You'd need to use ipchains to setup some masquerading/aliasing rules
for this to work - the 192.168.x.x address range is _not_ routed to the
internet - it's a private range reserved for use on _internal_ networks
connected to the net via NAT.

> On the same hub:
> 
> Machine 2: NT box with web server
> 	eth0:	203.x.x.2	netmask 255.255.255.0
> 	dafault route GW=139.x.x.x eth0
> I don't know how to add routes to NT Machines
> 
> Machine 3 and more on the same hub but with private addresses
> 	eth0:	192.168.0.1 	netmask 255.255.255.0
> route add net 203.x.x.0 eht0
> default route GW = 139.x.x.x eth0

The fact that the machines are connected to the same hub doesn't preclude
using multiple networks, no. However, expecting them to be routed to the
internet will lead to frustration unless you have some form of
firewall/NAT situation in place.

To repeat questions someone else asked - did you actually _buy_ all this
IP address space from Telstra when you connected, or are you just assuming
you can use any IP address you like? If you want two machines visible on
the net from inside your own network, you _must_ buy suitable IP addresses
- you can't have your web server on the net from a "fake" or private
address without much fancier equiptment than you apparently have.

DaZZa

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