bind(2) issue (cont.)

Behavior is different between implementations
OpenBSD
No, allow both sockets and ipv6 do not suck ipv4 traffic at all
NetBSD
Yes, allow both sockets and ipv6 do not suck ipv4 traffic by default.
FreeBSD
Yes, allow both sockets and ipv6 sucks ipv4 traffic if ipv4 socket is not bound