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Can I forward traffic coming into a dummy interface on to another interface? Or is it not a real interface at all even?

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     all  --  dummy0 eth6    anywhere             anywhere            
    0     0 ACCEPT     all  --  eth6   dummy0  anywhere             anywhere

I want all traffic reaching eth6 to go to dummy0, and all traffic reaching dummy0 to go to eth6.

Should I be doing something else really? (I can't use bridges or bonding).

JohnyTex
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1 Answers1

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Are you trying to just forward traffic without re-writing anything?

The way you've written your post makes me think that you are trying to get linux to act as an inline passive tap, but when you say that you want traffic going bi-directional I'm thinking you wanted an active tap.

My best guess right now without clarification of your goal would be something like:

http://backreference.org/2010/03/26/tuntap-interface-tutorial/

Raymond Bannan
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  • Can't use a TUN/TAP interface because traffic going to userspace will lower bandwidth too much.

    Actually what I want to achieve is to have a middlepoint where I can attach a GRE tunnel. I want to be able to forward traffic from this middlepoint to either a GPRS or Wifi interface at different points, while still having the tunnel intact.

    I also can't use bonding or bridges. :-(

     – JohnyTex May 07 '15 at 15:20
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    I think what you are proposing is basically to turn the box into a router, is that right? I believe bridging is the only means by which you could link two logical networks together without actually being the destination mac address in the frame. – Raymond Bannan May 07 '15 at 17:00
  • Thanks for your input! Do you know though, exactly what a dummy interface does? – JohnyTex May 12 '15 at 14:19
  • Your question prompted me to read http://www.tldp.org/LDP/nag/node72.html . Beyond the contents of that article, I couldn't exactly say how a dummy interface works. I still think I'm confused less about the dummy interface and more about what you are trying to accomplish. The way your original question is written, it seems to me you'd be making a broadcast storm with src: any dst: any bidirectional, so I made some assumptions. – Raymond Bannan May 13 '15 at 23:12