I need your help regarding a network configuration between different machines.

I have 6 Ubuntu servers which have two NICs, eth0 + eth1. eth0 has a public IP which connects to the internet through the provider gateway. eth1 is connected to a switch along with the rest of the servers and the interfaces are bridged together to form veths. With the current configuration the veths on each server communicate directly. After having a need to add two more servers, it was impossible for the hosting company to add them to the switch along with the others. So they made the same configuration with the NICs but this time the eth1 interfaces were connected with a crossover cable.

My question: Is it possible to route traffic from the secondary interfaces using either the public IP of eth0 on all machines, or using a VPN connection? I tried connecting one of the first six with one from the new servers using VPN and I had successful connectivity.

What I tried so far:

  • Route traffic to the veth network using the tunnel interface

    route add -net <veth_network> netmask xxx.xxx.xxx.xxx dev tun0

without luck

Is there an alternative?

  • 1
    What interfaces are you bridging? Sounds like you are saying that each server is bridging traffic between eth0 and eth1. But doing that would make no sense and likely break things, so I assume you meant something else. – kasperd Sep 22 '17 at 7:56
  • 1
    agree with @kasperd The question is not clear enough to get a good answer. It might help to have a diagram showing IP addresses and eth interfaces. – Scott Lundberg Sep 22 '17 at 15:24

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