libnfqueue-perl 0.5-1build2 / usr / share / doc / libnfqueue-perl / README

nfqueue-bindings was written to provide an interface in high-level
languages such as Perl or Python to libnetfilter_queue.
The goal is to provide a library to gain access to packets queued by
the kernel packet filter.

It is important to note that these bindings will not follow blindly
libnetfilter_queue API. For ex., some higher-level wrappers will be provided
for the open/bind/create mechanism (using one function call instead of
three).

Since libraries to decode ip packets are already available, the bindings
will use them.

Remember that an application connection to libnetfilter_queue must run as
root to be able to create the queue. Some extra steps may be required
to drop privileges after if you need more security.

You must add rules in netfilter to send packets to the userspace queue.
The number of the queue (--queue-num option in netfilter) must match the
number provided to create_queue().

Example of iptables rules::

 iptables -A OUTPUT --destination 1.2.3.4 -j NFQUEUE

Of course, you should be more restrictive, depending on your needs.