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Hi Folks, I've search the forums and the general internet for an answer to this perplexing problem I'm experiencing and can't seem to find a scenario that is similar to ...
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  1. #1
    Just Joined!
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    Configure 2 NICs - ext. static IPs on same network


    Hi Folks,

    I've search the forums and the general internet for an answer to this perplexing problem I'm experiencing and can't seem to find a scenario that is similar to mine. Here is my setup and problem:

    Linux (FC7) server has 2 NICs, both of which are on the same subnet and have static IPs. Below is an example of what my setup would look like:

    eth0: IP=71.245.97.81 SUBNETMASK=255.255.255.0 GW=71.245.97.1
    eth1: IP=71.245.97.82 SUBNETMASK=255.255.255.0 GW=71.245.97.1

    Trying to accomplish:
    I'm trying to configure the linux routing table so that incoming BIND queries on eth1, port 53, go out eth1 (the same way they came in). Additionally, I want incoming BIND queries on eth0, port 53, to go out eth0 (the same way they came in). In essence, I have ns1.myserver.com pointed to eth0 and ns2.myserver.com pointed to eth1.

    Herein lies the problem -- When I add a default gateway, it has to be one OR the other, but that doesn't work for my setup. When searching the forums and internet, I find lots of solutions if you happen to have two different networks setup on two different NICs. I do not -- both are on the same network.

    Keep in mind that I have Netfilter already configured to process and route/forward packets where they need to go. The big problem I have is routing responses out of both eth1 and eth0 (depending on how they come in, of course).

    Thanks a bunch!!

    --myrion

  2. #2
    Linux Guru anomie's Avatar
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    In the past I've assigned an IP and an alias on the same network to the same ethernet device.

    e.g.
    eth0 192.168.1.50
    eth0:0 192.168.1.51

    But never tried two different ethernet devices on the same network. Is the purpose of what you're doing to try to partition traffic..?

  3. #3
    Just Joined!
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    Aug 2007
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    Sort of, yes :)

    Quote Originally Posted by anomie View Post
    In the past I've assigned an IP and an alias on the same network to the same ethernet device.

    e.g.
    eth0 192.168.1.50
    eth0:0 192.168.1.51

    But never tried two different ethernet devices on the same network. Is the purpose of what you're doing to try to partition traffic..?
    So basically yes. There are two individual NICs within this system. Each one has a static IP assigned from my ISP (btw -- I have a 5-block of IPs). And yes, I'm definitely trying to partition traffic. Specifically, I'm running a name server (BIND) and I'm having both IPs assigned to the individual NICs represent ns1.myserver.com and ns2.myserver.com. That way there is some redundancy with respect to my DNS queries. And yes, I know, it doesn't *really* count because both IPs like to the same system. But that's a whole different thread.

    --myrion

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