What ports must be open in a firewall

[jppo]

Hello,

I wonder what TCP ports are to be left open in a firewall to let the tunnel work.

Regards

JPPO

[cholzhauer]

dont need to allow any ports..just protocol 41 and imho, ping

[snarked]

IPv4:  Protocol 41 from/to the tunnel server's IPv4 address.
IPv6:  ICMP6 echo-request and reply from/to the tunnel server's IPv6 address ending ::1 ("Server IPv6 Address Tunnel Endpoint") and your host's IPv6 address ending ::2 ("Client IPv6 Address Tunnel Endpoint").

To do anything useful, obviously your IPv6 routed address(es) must also be opened somehow.  That's up to you.