RE: 2 NIC's on same network, possible?

[Ghaith Nasrawi <libero () aucegypt edu>]

There will not be any confusion at all. The kernel will make one of the NICs 
as its default route, type "route" and you will see your routing table and be 
able to judge which interface is responsible on this. It will be either "eth0" 
or "eth1"

Regards,


./Ghaith
===============

Today is the tomorrow you worried about yesterday





-----Original Message-----
From: Vineet Mehta [mailto:vineet () linux com kw] 
Sent: Sunday, July 27, 2003 9:49 AM
To: security-basics () securityfocus com
Subject: 2 NIC's on same network, possible?

Hi all,

My collegue has a Linux machine which has 2 NIC's on it. What he did was
assign the IP's 192.168.0.6/24 and 192.168.0.7/24 to the NIC's. And he
was trying to ping the network but was getting errors (i dont know the
errors).

               -----------------
              | Switch         |
              |_________________|
                |             |
                |             |
                |             |
          -------------------------------
          |  NIC1            NIC2     |
          |192.168.0.6/24 192.168.0.7/24|
          |        Machine            |
          |-----------------------------|


I tried explaining him like this:->

Configuring the machine's network like this is not a big problem, coz
other machines on the network can still see these 2 IP's. But his
machine will not be able to reach other machines on the network coz 2
NIC's point to the same network so Linux kernel would be confused for
which NIC to use to send packets. If by any means we set the route to
use ANY one NIC to reach the network then there will be no errors.

Am i right in this, or this is not possible AT ALL? I took my thought
from the concept of IP Aliasing.

Thanks in advance for any help.

Regards,
-- 
Vineet Mehta
Network Security Consultant
Kuwait Linux Company
Kuwait
Ph-2412552/2463633
<vineet [at] linux [dot] com [dot] kw>
www.linux.com.kw


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