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Dharani Dharan
Asked: 2016-10-22 02:03:39 +0800 CST

How to create a private network with same production ip address? And How to make communication between using linux machine as router?

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I have production network in some IP series say 192.168.X.X in Vmware. In this i have some machine. I need to create a test setup. I have created a separate VLAN. Those VLAN were not connected to any physical adapter. I call it as "ISOLATED ENV". i have created the same machines as prod in "ISOLATED ENV". 

Physical_adpter----VLAN X ----> PROD_MACHINE          ISOLATED_ENV---->TEST_PROD_MACHI

i have gave same ip series in the production network to Isolated_Env. So ISOLATED_ENV machine IP's are same as production IP like 192.168.X.X.

Now i need to make a communication in between these network. i used a linux machine with 2 nic as router for this purpose.

But the issue, the communication will takes place either from one side. if i enabled the nic2 and gave the production network gateway is the IP in NIC2, the communication from Linux machine to ISOLATED_ENV will works. But I cant ping from prod network to Linux machine (Router).

How can i achieve this? i configured IP forwarding some other ip rules in the Linux machine.

If i configured this with 2 different networks means it will work. if i am giving the same ip address as prod it wont.

Help me out. Thanks in advance.

router nat ip-routing linux-networking ip-forwarding

1 Answers

  1. When you give 2 addresses in the same range on one Linux machine, it will choose (maybe randomly) which one will be the default route for the range.

    The solution for you is I think to bridge the both NIC so, they will answer the same IP on the two ports.

    Lets assume your interface are eth0 and eth1, you can acheive this doing:

     - brctl addbr br0
 - brctl addif br0 eth0
 - brctl addif br0 eth1
 - ifconfig eth0 0.0.0.0
 - ifconfig eth1 0.0.0.0
 - ifconfig br0 up or ifconfig br0 192.168.100.5 netmask 255.255.255.0 up

    You can replace the 3 last steps by edditing /etc/syconfig/network-scripts/ifcfg{eth0/eth1/br0} You then only want to have your eht0 and eth1 activated but with bootproto=none and setup your "virtual" nic br0 as dhcp or static ip.

    Kind regards

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