support ipv6

[jasonwee]

Tested the following changes works for servers that has ipv6 enabled, but there are still some more which need time to fix. Example below:

• now using stateful? change to the stateless , means don't use something like this --state NEW
• when vnet is enabled, connection get timed out, yes connection time out but not unable to connect.
• support ipv6 address into global, local allow and deny rules