Netfilter Queue Howto

Extensions

通过加载extensions可以获得specified options 例如tcp extensions:

QUEUE is a special target, which queues the packet for userspace processing. For this to be useful, two further components are required:

• a “queue handler”, which deals with the actual mechanics of passing packets between the kernel and userspace; and
• a userspace application to receive, possibly manipulate, and issue verdicts on packets.