Openvpn Version 2.3.14 will not work with 2.4.0

pzi123

I see this thread went cold a year ago.

https://forums.openvpn.net/viewtopic.php?f=6&t=21337#p60060

I see the same behavior of the windows 2.3.14 client - as reported by Pippin - that the tun interface on the windows 10 side with ipv6 settings reports the error:

Apr 4 09:15:15 pzi-c7-1 openvpn[2332]: client/192.168.77.4:64070 MULTI: bad source address from client [::], packet dropped

and then blocks all the IO. The manual change in the windows tun interface properties to disable ipv6 enables the IO and VPN is operational. Is there a workaround for the windows client in the configuration file or elsewhere?

pzi123

That windows-10 2.3.14 client would not work with centos-7 2.3.14 server without that manual ipv6 fix. I upgraded the client to 2.4.1 and the 'MULTI' error is gone but the end result is the same - no data flow from client to the server after establishing the session. Well no option but go forward - compiled the 2.4.0 server on centos 7 and all works fine now - 2.4 server and 2.4 client. Lesson - versions don't mix well here.

TinCanTech

I run multiple versions of openvpn in production and for testing but I have never seen an incompatibility issue between version 2.3.14 and 2.4.x ..

The development of openvpn takes great care to ensure compatibility between versions. Where such incompatibilities exist they are well documented .. so yours is a bold claim and, without suitable evidence, is probably unfounded.

With regard to evidence, please see:
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