Change default Wintun driver file path

[northis]

Issue Details

We use default wintun driver file name wintun.sys. This leads to conflicts with Open VPN

Proposed solution

Patch the library wintun.dll and change wintun.sys name

Alternative solution

No response

[shamarin]

Seams that OpenVPN will not fix it. Their answer:
"The author of wintun has requested to only ship the binaries of wintun that he builds himself and use the installation way that the current binaries have builtin. We respect his intents and have never updated to the newer versions of wintun as consequence. Instead we are focusing on ovpn-dco-win for windows.

Our wintun driver is not patched or modifed. Where did you get the idea that we are patching it? It is just an older version/last version before breaking changes in upstream. The observed behaviour of deleting all wintun interfaces is by design by the newer wintun driver version/dll.

From my understanding, the license of the new version also only allows using the wintun driver only if you use the signed binaries. So that means that you cannot build the wintun driver yourself and use/distribute OpenVPN with a driver that is built from soure as GPL is incompatible with Apache2 license that is used by OpenSSL in OpenVPN. OpenVPN itself has an exception for this."

OpenVPN/openvpn-build#720