I need to get acces to multiple remote LAN (not specially at the same time) from my office (Fixed IP).

All these remote LAN will be connected to internet via 3 or 4G USB key and will have dynamic IP address.

An OpenVPN Server is running in my Office

Note : I want to avoid DynDNS service to reduce cost.

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Question : How can I tunnel to my 3/4G gateway if it has dynamic IP (and no DynDNS) ?

My first guest was to establish a first tunnel from my 3/4G gateway to my office which have a fixed IP. And then establish a second tunnel from my office to the 3/4G gateway.

Note : I have multiple 3/4G gateway with the same LAN configuration and I want to find a way to tunnel to each one.

  • You really only need DynDNS if your server was also using a dynamic IP. Since that's not the case here, you should be able to use a standard OpenVPN config with a server on your side and a client on the client gateway. If you set things up correctly, once the client has connected to the server, you should be able to communicate with the devices on each client location without doing any special on your computer. I may have missed something but I do not see what you were trying to do with the server on the client gateway side. Jan 31 '16 at 5:19
  • I edited my question to clarify, sorry for the poor formulation. As you said if the client (dynamic IP) connect to the server (fixed IP) I should be able to communicate with the remote devices but I have multiple 3/4G client like this with the same LAN configuration and the same local IP addresses. I need to find a way to tunnel from my office to these remote 3/4G gateway.
    – Thomas N.
    Feb 2 '16 at 13:45

My understanding is that you have multiple remote sites to connect to with:

  • dynamic public IPs
  • identical LAN IPs from one to the other.

Those are actually two separate issues with completely different types of solutions. Handling dynamic public IPs can be done with a standard OpenVPN configuration (no DynDNS). Once the VPN part is in place, you should NAT each LAN to a distinct private IP range, such that your workstation thinks it sees different remote LANs.

So if all the LANs use, you would map the first one to (for example), the second one to, etc...

Without knowing more about the specific hardware, it's hard to say whether this is best done on your central gateway or on the remote site gateways, though.

  • I misunderstood how VPN works... My clients (with dynamic IP) start the connection and with the right route I can access each client LAN. As you said I mapped each client to a specific subnet and route the LAN. Thank for your answer!
    – Thomas N.
    Mar 29 '16 at 16:57

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