Can OpenVPN use an existing tunnel device instead of dynamically creating a new one?

Question

I wondered, if the following scenario is possible:

If I create a new tunnel adapter on startup of my ubuntu server 14.04, can I tell an OpenVPN client to use this tunnel instead of creating a new tunnel for itself?

The thought behind this is that I could allow a normal user to create an OpenVPN connection through said client without giving root privileges needed to create the tunnel.

Answer 1

From the OpenVPN manual page:

--dev tunX | tapX | null

TUN/TAP virtual network device ( X can be omitted for a dynamic device.)

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Create a persistent tunnel device with:

sudo openvpn --mktun --dev <tun-name> --user <user-name> --group <group-name>

<tun-name> will be the tunnel device name. It should be "tun+number" (tun0, tun1, etc.).

<user-name> and <group-name> refer to user that will own the tunnel device.

Then you should use the same tunnel device name in the OpenVPN client. Instead of using --dev tun (command line parameter) or dev tun (configuration file), you should specify the name of the persistent tunnel device you created: --dev <tun-name> (command line parameter) or dev <tun-name> (configuration file).