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4Jan/180

Using OpenVPN For All Network Traffic Except For LAN

Hi!

Recently I noticed that my Android smartphone was not able to connect to YouTube via third-party apps. I narrowed it down to the issue with it being able to resolve hostnames to the correct IPv6 addresses but not being able to connect to them (somehow the IPv6 part of my internet connection is broken. A problem for a different time).

In order to work around the problem I am using an OpenVPN connection which automatically forces all outgoing connections to use IPv4, not IPv6. The only problem was that internal LAN connections did not work any more.

In the .ovpn configuration file I am using

redirect-gateway local def1

(because it is a WiFi connection), but I was also using

redirect-gateway def1

before that, which did not make any difference in that regard.

If add a route directive like the following one after the redirect-gateway directive, you can add a route to the routing table, directing all traffic for the specified route to the WiFi connection instead of the VPN connection:

redirect-gateway local def1
route 192.168.0.0 255.255.255.0 net_gateway

You will probably have to adjust the network address and maybe even the subnet mask to match your network.

The routing table is basically a prioritized table which lets the operating system decide which network adapter it should use for a specific connection. With the above entry you add a rule with a higher priority, overriding the generic one(s) from the OpenVPN connection configuration. These ones are added because of redirect-gateway def1 and tell the operating system to send all traffic via the virtual VPN network adapter, effectively sending it all over the VPN.

If you are configuring this from the OpenVPN server side, of course you can still use these directives, but in the context of the push directive. I am not doing that, however, so I saved both directives in the client configuration.

Now I can watch / listen to YouTube videos with third-party apps AND connect to LAN devices!

I hope this was helpful to you.

Thank you for reading!

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