This commit introduces the wireguard.Enpoint struct.
It encapsulates a DN name with port and a net.UPDAddr.
The fields are private and only accessible over exported Methods
to avoid accidental modification.
Also iptables.GetProtocol is improved to avoid ipv4 rules being applied
by `ip6tables`.
Signed-off-by: leonnicolas <leonloechner@gmx.de>