how to forward packets on two NICs - Networking

This is a discussion on how to forward packets on two NICs - Networking ; Hi all I have to build a sniffer on our voip network so as to monitor what is going wrong on it (bad communications quality) and my problem is that I can't mirror the traffic because the switchs are not ...

+ Reply to Thread
Results 1 to 4 of 4

Thread: how to forward packets on two NICs

  1. how to forward packets on two NICs

    Hi all

    I have to build a sniffer on our voip network so as to monitor what is going
    wrong on it (bad communications quality) and my problem is that I can't
    mirror the traffic because the switchs are not manageable. All the IP phones
    are on the same subnet and the IPBX is the gateway.
    Because I am not familiar with Voip protocols, I don't know really how all
    this stuff is working... And I am looking for a solution which won't need to
    change the IP topology... if it's possible.


    I had the idea to configure the sniffer with two NIC and to forward all the
    packets from one NIC to the other one, like a switch with 2 ports if you
    want (I know that this is not a very good way to act but has I have said, I
    would like to avoid changing the IP of the IPBX).

    Do you think it is a solution ? If yes, do you know how to configure that ?
    if no, do you see another solution ?

    I have found a package call parprouted which allows to forward the ARP
    requests, now I guess that I just have to find the same thing for IP packets
    as there is no dhcp/bootp protocols here...


    thanks in advance



  2. Re: how to forward packets on two NICs

    On Mon, 03 Nov 2008 16:03:26 +0100, Julien Simbola wrote:

    > I had the idea to configure the sniffer with two NIC and to forward all
    > the packets from one NIC to the other one, like a switch with 2 ports if
    > you want (I know that this is not a very good way to act but has I have
    > said, I would like to avoid changing the IP of the IPBX).


    This is called a bridge...

    Google for linux bridge howto..!


    --
    Regards/mvh Joachim Mæland

    If everything seems under control, you're just not going fast enough.
    -Mario Andretti

  3. Re: how to forward packets on two NICs

    I have been able to set this up, thanks to you Joachim

    For those who are interested in a solution, it's pretty simple
    Here is the way to proceed (using 2.6 kernel):

    apt-get install ebtables
    apt-get install bridge-utils

    brctl addr br0
    brctl addif br0 eth0
    brctl addif br0 eth1

    ifconfig br0 up


    thank you
    cheers





    "Joachim Mæland" wrote in message
    news:hqh3u5-329.ln1@snila.linuxgutta.no...
    > On Mon, 03 Nov 2008 16:03:26 +0100, Julien Simbola wrote:
    >
    >> I had the idea to configure the sniffer with two NIC and to forward all
    >> the packets from one NIC to the other one, like a switch with 2 ports if
    >> you want (I know that this is not a very good way to act but has I have
    >> said, I would like to avoid changing the IP of the IPBX).

    >
    > This is called a bridge...
    >
    > Google for linux bridge howto..!
    >
    >
    > --
    > Regards/mvh Joachim Mæland
    >
    > If everything seems under control, you're just not going fast enough.
    > -Mario Andretti
    >




  4. Re: how to forward packets on two NICs

    Hello,

    Julien Simbola a écrit :
    >
    > Here is the way to proceed (using 2.6 kernel):
    >
    > apt-get install ebtables
    > apt-get install bridge-utils


    Ebtables is not required to set up a simple bridge. It is required only
    to do layer 2 filtering/mangling on the bridge. Bridge-utils works with
    a 2.4 kernel too.

+ Reply to Thread