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Date:      Fri, 5 Aug 2016 04:14:05 +1000 (EST)
From:      Ian Smith <smithi@nimnet.asn.au>
To:        Julian Elischer <julian@freebsd.org>
Cc:        "Andrey V. Elsukov" <ae@freebsd.org>, lev@freebsd.org, freebsd-ipfw@freebsd.org, "Alexander V. Chernikov" <melifaro@freebsd.org>
Subject:   Re: IPFW: more "orthogonal? state operations, push into 11?
Message-ID:  <20160805034606.K56585@sola.nimnet.asn.au>
In-Reply-To: <3c3d7026-ea60-c0dd-527b-edd841274585@freebsd.org>
References:  <9229d4f7-8466-57b0-c954-117736102bd7@FreeBSD.org> <5755F0D3.9060909@FreeBSD.org> <5759DB79.10205@FreeBSD.org> <3d09497c-136c-e217-154c-ba00e6879c6f@freebsd.org> <20160616005016.A15883@sola.nimnet.asn.au> <d7bef617-70a4-f761-7d09-9413eb720b11@freebsd.org> <64d6bdea-fa32-f16f-2fdd-abd33d54d04e@freebsd.org> <46d5cfde-c4ac-ebd0-3c13-2759037621f3@FreeBSD.org> <11a5d41b-109a-434b-e8e0-7ed2826a8cc9@FreeBSD.org> <ee745842-c33e-4e73-f84c-6eb11f283b51@FreeBSD.org> <a3e98e25-4c0d-56ad-5640-0b6f13ebeb21@freebsd.org> <6c2ebc59-c5b8-5be0-8842-897b2de44d1f@FreeBSD.org> <3c3d7026-ea60-c0dd-527b-edd841274585@freebsd.org>

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On Fri, 5 Aug 2016 00:12:37 +0800, Julian Elischer wrote:
 > On 4/08/2016 6:50 PM, Andrey V. Elsukov wrote:
 > > On 04.08.16 06:42, Julian Elischer wrote:
 > > > so it's a combination of #1 and #2 in my list.  I think I originally
 > > > thought of having just #1.
 > > > 
 > > > A combination is less useful for me as you need to do:
 > > > 
 > > > 20 skipto 400 tcp from table(2) to me setup record-state
 > > > 21 skipto 400 tcp from table(2) to me setup
 > > > to make the entire session do the same thing.

 > > So, in your example what wrong with just using keep-state?
 > > "record-state without immediate action" == "keep-state without implicit
 > > check-state" needed to solve issues with NAT or something similar, that
 > > was described by Lev.
 > > 

 > because keep-state is a check-state for ALL packets going past, regardless of
 > whether they match the pattern.
 > 
 > at least that's what I have observed.

Except now(?) with named states/flows/whatever, isn't it the case that 
check-state [flowname] only affects packets with same state/flowname? So 
you can clearly separate, say, packets on different interfaces, packets 
coming or going on any interface, and such?

If I'm understanding that right - quite possibly not! - then only those 
packets will match, and others with other names (including 'default') 
won't match states with that name.  I'm not sure I'm expressing this at 
all well, because I'm only just starting to get any sort of grip, but 
I'm liking the idea and wondering if it's sufficient for starters.

To me, orthogonality implies the least number of commands/instructions 
that will accomplish the desired functionality.  First, let's find out 
what can and cannot be accomplished with named states/flows .. I'm yet 
to understand what record-state-without-action can accomplish apart from 
that .. it could work only for the first packet I suppose, since once 
state is established, further packets will match and follow state, no?

Again, I find concrete examples - like the use of valtype skipto,fib 
mentioned above - really helpful, essential really, for bears of such 
little brain as I ..

cheers, Ian



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