I'm using a Debian Sid Linux distro, and for many years my VPN setup has been working without any problems. For some reasons, when I upgraded the openvpn package from the 2.6.15 version (the last working one) to 2.7.0/2.7.1, the VPN connection breaks.
It looks like that VPN works just fine:
...
Incoming dynamic tls-crypt: Using 256 bit message hash 'SHA256' for HMAC authentication
Initialization Sequence Completed
Data Channel: cipher 'AES-256-GCM', peer-id: 65558
Timers: ping 10, ping-restart 60
Protocol options: explicit-exit-notify 1, protocol-flags cc-exit tls-ekm dyn-tls-crypt
But when I try to ping, I can't get any answer and in the syslog I see many of the following messages:
kernel: ip_tunnel_core: Dead loop on virtual device tun0, fix it urgently!
kernel: ip_tunnel_core: Dead loop on virtual device tun0, fix it urgently!
kernel: ip_tunnel_core: Dead loop on virtual device tun0, fix it urgently!
....
Basically there's no touch to the VPN config or any other parts of the system. When I revert openvpn to the older version, everything goes back to normal again.
I've rather advanced VPN setup, which allows me to choose (based on GID) which processes go through the VPN connection. I wrote a blog article concerning this setup (it's in Polish, but all the necessary commands are included).
What has changed between 2.6.15 and 2.7.0/2.7.1 that may cause this issue?
