LAN Client unreachable when connected to PIA OpenVPN

hash_key

Hi,

I am trying to understand why the following is a problem.

1.I have an ASUS RT68U Router on which i have enabled OpenVPN Server.

2.I can successfully connect to the OpenVPN Server using an external connection e.g. use OpenVPN app on iOS to connect with .opvn exported file. Once i am connected to the OpenVPN Server, I can successfully connect to local clients on the LAN (e.g. Mac Pro, the Router, other LAN clients etc).

3.However, if i turn on OpenVPN Client connection on the Mac Pro using TunnelBlick e.g. connect to PIA on the Mac Pro, the Mac Pro will become unreachable via the external connection tunneling through the OpenVPN Server (e.g. cannot ping the machine anymore). As soon as the Mac Pro disconnects from PIA, it is reachable again.

Why is this? Is there some kind of conflict occurring.

Apologies if the description is hazy, here are the various configurations that work and do not work where the second configuration is the one i am trying to understand:

1.External Client <---> OpenVPN Server <---> Router <---> Mac Pro : REACHABLE

2.External Client <---> OpenVPN Server <---> Router <-X-> Mac Pro connected to PIA OpenVPN Client : NOT REACHABLE

3.Internal Client <---> Router <---> OpenVPN Client <---> Mac Pro : REACHABLE

Does that make sense?

I am new to this. If there are some logs i can look at i can do that. However something tells me this comes down to the way OpenVPN works... when i make the OpenVPN Client connection to PIA on the Mac Pro, the way the LAN is configured changes somehow on the Mac Pro? This then makes it 'invisible' to a device connecting to the Router via the OpenVPN Server.

Traffic

When connected to PIA your MAC default gateway is redirected to the PIA service, which is why you cannot see it on your LAN at that time.

hash_key

Thanks for your reply.

How do i determine if this is true? Or more importantly set the default gateway to be the same as the Router? or does that defeat the purpose of VPN via PIA?

Traffic

A better approach for you would be to add a route for your VPN to the MAC.

hash_key

Alright well i have tried to understand how to do that using the following guide:

https://forums.openvpn.net/topic9465.html

Based on the above guide, i ran the following command on the Mac Pro:

sudo route add 192.168.0.0 -netmask 255.255.255.0 192.168.1.111

The terminal returned with the following indicating it is successful:

add net 192.168.0.0: gateway 192.168.1.111

However this made difference. I have not rebooted the Mac Pro - was sure if that is necessary.

Traffic

hash_key wrotesudo route add 192.168.0.0 -netmask 255.255.255.0 192.168.1.111

Your VPN subnet is 192.168.0.0 :?:

I suggest you Please see the Forum rules (top of this page)

hash_key

Sorry I was trying to follow the guide explicitly hence why I used that subnet. As you can probably tell when it comes to networking I am pretty deficient.

I understand what you say is the problem but I am failing to technically implement a solution.

Will read the rules again.

Traffic

You could also use iptables MASQUERADE on your router for your private VPN.

hash_key

Okay after a bit of sleep, some thinking about your suggestions and testing, this finally solved the problem:

sudo route add -host 10.8.0.0 -netmask 255.255.255.0 192.168.1.1

where 10.8.0.0 is the OpenVPN Server (via the ASUS AC68U) subnet and 192.168.1.1 is the routers IP.

Thanks for your help!