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

From: Ghaith Nasrawi (libero_at_aucegypt.edu)
Date: 07/29/03

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    Date: Tue, 29 Jul 2003 11:37:36 +0300
To: security-basics@securityfocus.com

    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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