0

Does connecting to a shared-IP VPN expose local ports to other users of the same VPN server? Does a VPN tunnel neutralize the protection offered by a NAT router? Are local ports reachable from a compromized VPN server? Assume OpenVPN.

Is this a matter of configuration of the OpenVPN server? If so, how to check? Is it necessary to explicitly close the ports via local iptables rules even if machine is behind a NAT?

The closest I could find is this (too vague) and this (unclear).

2

Yes, depending on the setup of the server, a shared-vpn can expose local ports to other users of the same VPN server, and it does bypass NAT.

Mitigating/fixing this is not so much a matter of configuration of the OpenVPN server as ensuring iptables is running on the local machine and blocking ports as appropriate. Running a local firewall is always a good idea.

Its difficult to check as it depends on the VPN setup of your provider and what access you have. If you have 2 devices with VPN connections to the same provider you could use 1 device to portscan the other device to give you some comfort.

Also, security is not an either or, rather its built up of layers - In addition to looking at the forwarding of packets to your system, look at the apps you are running and see what can be done to lock them down - that way you can gain protection at a different layer.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.