[PVE-User] Proxmox KVM VNC socket is not reachable in IPv6

[StalkR]

Hello,

I'm new to Proxmox and it's a really good product.
However, there is a minor issue I've encountered while using the
Proxmox interface in IPv6.

I can browse the Proxmox interface in IPv6 (Apache listens on IPv6
TCP) but when I click on "Open VNC console" for a KVM VM it does not
work. Indeed the applet tries to connect to the socket created with
netcat but GNU Netcat has no IPv6 support and only creates an IPv4
socket.
I first thought replacing netcat with netcat6 would be the solution,
however it does not have -c switch (spawn a shell and run command) but
only -e (exec) and I think it is why it does not work.
Then I tried with socat - which syntax is different than netcat - but
I could not make it work either (I think for the same reason than
netcat6, only EXEC parameter).

In the meantime, an alternative solution can be to create an IPv6-only
TCP server which forks and forwards data to the IPv4 TCP socket
created by netcat. I'm doing this with socat:
$ socat TCP6-LISTEN:5900,ipv6only=1,fork TCP:localhost:5900

Any ideas?

Sincerely,
StalkR