[plug] VPNs

[Leon Brooks]

Rob Hall wrote:
> 
> Got a question for the routing Gurus out there.
> 
> An associate (of whom I mentioned in a mail yesterday - yes he is _very_
> dangerous when left alone on a Linux box) has a client that is running a VPN
> (Virtual Private Network) with Telstra.  What it constist of is:
> 
> SITE A
> 6 PC's connected to a router (Not sure what the address is)
> They have IP addresses in the range of 10.3.26.? (I think)
> 
> SITE B
> 12 pcs connected to a router (Telstra set it up as 10.3.26.1)
> IP addresses are 10.3.26.? (I am sure about this one)
> 
> Both sites are connected by ISDN over the internet.  They broadcast over a
> registered internet IP address.
> 
> Now SITE A has a Windoze based accounting system served from a Linux box
> that they want access from SITE B.
> 
> Now my understanding of IP networking is that it is impossible for one of
> these networks to have direct access to the other as long as they are
> separated by the internet IP address.  I thought that at least all servers
> and routers would need Class C addresses.
> 
> Could it be that the routers actually have a Class C address and that they
> do some sort of IPchains (or ipfwadm) equivalent thing and just forward the
> requests on to the local server?  In that case, to map the drives (in
> Windows) on the server at SITE B from SITE A would require you to use the
> Class C address.  Is this correct?

IP Tunnelling, it's called, or IP-over-IP. You'll see it in your kernel.
Dunno where you'd find details on it, can't see any HOWTO.

-- 
If a `religion' is defined to be a system of ideas that contains
unprovable 
statements, then Godel taught us that mathematics is not only a
religion, 
it is the only religion that can prove itself to be one. -- John Barrow