(FreeBSD IPv6 Mostly)禁用IPv6以提升Telegram加载速度

直接把官方的cidr地址块给deny了，返回Destination unreachable: Administratively prohibited，不用等客户端SYN发出等待回复了

ipfw add 90 unreach6 admin-prohib ipv6 from any to 2001:b28:f23d::/48
ipfw add 91 unreach6 admin-prohib ipv6 from any to 2001:b28:f23f::/48
ipfw add 92 unreach6 admin-prohib ipv6 from any to 2001:67c:4e8::/48
ipfw add 93 unreach6 admin-prohib ipv6 from any to 2001:b28:f23c::/48
ipfw add 94 unreach6 admin-prohib ipv6 from any to 2a0a:f280::/32zh 

重启防火墙

service ipfw restart