4. Questions about netfilter development

4.1 I don't understand how to use the QUEUE target from userspace

A library called libipq is provided for userspace packet handling. There is now documentation for this in the form of man pages. You need to build and install the iptables development components:

make install-devel

then see libipq(3).

You may also be interested in the Perl bindings for libipq, Perlipq at: http://www.intercode.com.au/jmorris/perlipq/. The binding itself is an example of using the library.

Other code examples include:

• testsuite/tools/intercept.c from netfilter CVS
• ipqmpd (see http://www.gnumonks.org/projects/)
• nfqtest, part of netfilter-tools (see http://www.gnumonks.org/projects/)

4.2 I want to contribute some code, but have no idea what to do

The netfilter core-team keeps a TODO list where it lists all the desired changes / new features. You can retrieve this list via anonymous CVS, instructions are on the netfilter Homepage. Alternatively you can also go to http://cvs.samba.org/cgi-bin/cvsweb/netfilter/TODO/ using CVSweb.

4.3 I've fixed a bug or written an extension. How do I contribute it?

If you want to publish it, please send it to the netfilter-devel mailinglist. Subscription instructions are at http://lists.samba.org/mailman/listinfo/netfilter-devel/.

The correct way of sending a patch is the following :

• Subject starting with [PATCH]
• Included straight in the body of the message, not MIME'd.
• a cvs-checkin/Changelog entry outside the diff.
• `diff -u old new' form, from outside root directory (ie. can be applied with -p1 when sitting in the untarred dir.