IPFW: shape and status in CURRENT

From: O. Hartmann <ohartman_at_zedat.fu-berlin.de>
Date: Thu, 29 Sep 2016 21:02:16 +0200
Hash: SHA256

Since a couple of months now, I use IPFW on several projects. I use IPFW again after a
long term hiatus since ~ 2003. Before I used pf. The reasons are mannyfold and one reason
is very dogmatic - it is the FreeBSD's native firewall and several performance diagrams
shown in the net tells me a significant performance benefit in case being setup optimal
over pf. pf in FreeBSD lacks behind the OpenBSD's development.

Since last year I try to setup IPFW only on all of our systems. So I do also at home
and at some places, where we have to use NAT via PPPoE/modem. And here the struggle
begins. While most setups of a firewall on a router/gateway with several NICs directly
attached to the internet with on interface, the outbound interface, the same starts to
be a horrible story when it comes to NAT.

The handbook offers some simple examples, but in most cases, I see the supposed to be
outdated external natd daemon still in favour over in-kernel NAT! This is also the
case with the manpage for ipfw(8). I miss a more recent example of setting up NAT with
in-kernel NAT and the caveats of one-pass and none-one-pass and some hints how the IP
packet's header gets rewritten when being translated by NAT and reinjected into the
pipeline. For me, as a non-source-code-expert-and-simple-system's administrator, it is
sometimes hard to understand how IPFW works. And the problems reported do tell me that
I'm not alone.

The handbook has some examples. One of them contains a traversal of 37/TCP, timeserver.
It is a long time since I saw this kind of setup, most time synchronisation methods use
NTP and 123/UDP. The example also seems a bit outdated.

Manpage firewall(7) lacks also of an modern in-kernel NAT example - it still referes to
the natd. Also, there is a kind of anti-spoof rule shown that leaves the impression that
this page is quite antique. Doesn't IPFW has a antispoof rule, or even "verrepath" as
the manpage ipfw(8) states?

Somehow I miss some more detailed explanations what happens with check-state, since this
causes much trouble, even in combination with NAT.

Well, as said, I'm no expert, maybe I'm simply too blunt to understand, but again, it
seems I'm not alone. People switched to pf and even Apple moved from ipfw to pf. That
leaves the question here: what is the status of the development of IPFW in FreeBSD? is it
maintained-only or is there development going on? Are there plans for refurbished, more
up to time man pages and examples?

Thanks in advance and for your patience reading my bad English.

Version: GnuPG v2

Received on Thu Sep 29 2016 - 17:02:25 UTC

This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:41:08 UTC