[CentOS] Addressing outgoing connections to a specific interface

Dotan Cohen dotancohen at gmail.com
Mon Nov 8 04:34:00 EST 2010


On Sat, Nov 6, 2010 at 23:19, Bob McConnell <rmcconne at lightlink.com> wrote:
> To amplify this just a little bit, by the rules of IP routing, every
> machine must:
>
> A) Have a unique address.
> B) Be attached to the proper subnet for that address as defined by the
> local netmask.
>
> Once those are true, there exists a unique route between any two
> machines connected to the network, or the Internet.
>

Both those conditions are met in this use case, however the machine in
question is on two networks:

|--Network1--|--Network2--|
A            C            B

A: router on the wireless network
B: router on the wired network
C: CentOS laptop

Each router has a unique address on it's own network, as per spec.
The laptop is connected to two networks, on two different interfaces.
The networks were never designed to be connected, and in fact there is
no connection between them.

Correct me if I'm wrong, but NAT is what C would do to let a computer
on Network1 access a resource on Network2. C would be the gateway,
rerouting packets between the two networks and correcting for address
used on both sides.

However, I am not trying to create a gateway! In this case, C itself
(as a workstation) needs to access resources on both networks.


-- 
Dotan Cohen

http://gibberish.co.il
http://what-is-what.com


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