reinstate "Update ftp-proxy for changes to ipnat_t" from Darren Reed

branches: 1.5.6;
Back out the recent import of IPFilter 5.1.1 for the upcoming branch,
which will now have IPFilter 4.1.34. IPFilter 5.1.1 will be restored
post-branch.

ok: core, releng.

Update ftp-proxy for changes to ipnat_t

branches: 1.3.4;
NPF checkpoint:
- Add libnpf(3) - a library to control NPF (configuration, ruleset, etc).
- Add NPF support for ftp-proxy(8).
- Add rc.d script for NPF.
- Convert npfctl(8) to use libnpf(3) and thus make it less depressive.
Note: next clean-up step should be a parser, once dholland@ will finish it.
- Add more documentation.
- Various fixes.

branches: 1.2.16;
merge yamt-pf42 branch.
(import newer pf from OpenBSD 4.2)

ok'ed by peter@. requested by core@

branches: 1.1.2;
file ipf.c was initially added on branch yamt-pf42.

Basic support for IP-Filter, only tested with passive mode.
This should probably be re-written to use the ipnat state put interface.

Sync with HEAD

sync with head

Resync to 2012-11-19 00:00:00 UTC