feature: add tun2tap support for tun client with tap server

[pengtianabc]

Add a optinal param for tun2tap: tun client can connect with tap server.

[pengtianabc]

Some device like android and ios can not use tap mode, i added one --tun2tap option of handle arp on tun on client side, so we can use tun client with tap server.

[cron2]

Hi,

On Sun, Apr 12, 2020 at 07:18:33PM -0700, pengtian wrote: Some device like android and ios can not use tap mode, i added one `--tun2tap` option of handle arp on tun on client side, so we can use tun client with tap server.

This is definitely interesting stuff. Arne and I have been thinking of writing something like this, so we can see the motivation :-) - now we just need to find time for a code review. gert

…

-- "If was one thing all people took for granted, was conviction that if you feed honest figures into a computer, honest figures come out. Never doubted it myself till I met a computer with a sense of humor." Robert A. Heinlein, The Moon is a Harsh Mistress Gert Doering - Munich, Germany gert@greenie.muc.de

[pengtianabc]

I think i have handled all knowned issues.

[pengtianabc]

• Sample usage: client side: --dev tun --topology subnet --tun2tap; server side: --dev tap --topology subnet
  in some incorrect config, ip address on tun device is error
• Known bugs: can not use with compress

[schwabe]

Just gave the code a quick look and although the issues I pointed out before are marked resolved, the issues are not resolved. To be included in OpenVPN we still need the code to be improved.

[ordex]

hey @pengtianabc are you still interested in working on this PR? It's definitely good work, so it'd be nice to see it evolving properly.

[pengtianabc]

hey @pengtianabc are you still interested in working on this PR? It's definitely good work, so it'd be nice to see it evolving properly.

I am glad that someone are still interested in this feature.
But i am busy recently, so i will try to solve issues and merge into latest when vacation.

[pengtianabc]

Hey guys, i am try to understand mac address resolusion in ipv6. In ipv4, we can replace request to mac boardcast to get target mac address, but how to do that in ipv6?

[ordex]

@pengtianabc in IPv6 there is a Neighbor Discovery (ND) protocol that takes care of that.