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VPN Issue

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by alfa11

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Hey guys.
I need to set up a VPN connection between two routers. The thing is that both sides use the same range, so they asked me to route the machines through a public IP address.
My questions is how to do this because the vpn device has already an ip address (public), after it makes the tunnel with the other, how can it route the workstations through another public IP???
Hope anyone help me with this or give some URL where I can find an explanation.
Thanks in advance

5 replies

by churdoo

You did say VPN, and if I understood your post correctly -- when you said "The thing is that both sides use the same range," did you mean that the local network for each side is the same, for example 192.168.1.0/24 in site A and 192.168.1.0/24 in site B?

If this is the case, you can't do this with a VPN tunnel, the two sides of the tunnel need to be different networks, such as 192.168.1.0/24 in site A and 192.168.2.0/24 in site B.

Unless some advanced router guy (or girl) knows another way, I say you need to IP renumber 1 of the networks.

by alfa11

The other side requirements are the ones I posted, we must do NAT through an public address.
As this is a future client we can't change this requirement :(

by jdclyde

Because the way your router works, it would not understand a gateway to the same network.

This is creating a bridged network segment that would allow all the local chatter to cross your VPN (provided you could get it to work in the first place) making the network overhead unusable.

Most networks are using DHCP anyways (tool of the lazy admin) so have the simpler of the two topologies change.

by sfix

I don't know what hardware you're using, but some devices handle this quite well. I have vpn tunnels with clients that cover both scenarios that address this. With several clients I had to create a 'proxy' on my side that translates all of the 192.168.x.x addresses to 172.16, for example, to handle the overlapping subnets.

I have a couple other clients who required that the one device they needed to connect to had to have a registered IP. Hopefully you have support on your devices and have already figured out a solution by now.

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