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Date:      Tue, 21 May 1996 00:47:39 -0500 (CDT)
From:      Tony Kimball <alk@Think.COM>
To:        bmah@cs.berkeley.edu
Cc:        terry@lambert.org, questions@freebsd.org
Subject:   Re: ip masquerading
Message-ID:  <199605210547.AAA20060@compound.Think.COM>
In-Reply-To: <199605210513.WAA24403@conviction.CS.Berkeley.EDU> (bmah@cs.berkeley.edu)

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   From: bmah@cs.berkeley.edu (Bruce A. Mah)
   Date: Mon, 20 May 1996 22:13:03 -0700

   Tony Kimball writes:
   > Hey, I'm not the one who wants to recover state.  I'm just trying
   > to scam out how it could be done.  You've got a good 15.97 bits to
   > work with...

   It's also kind of hard to cram 32 bits of IP address and X bits of 
   port/application/whatever (where X is small) into 16 bits of port 
   number, without needing some other kind of shared state.

But of course you don't need 32 bits of IP.  If you allocated 7 bits
to a client IP table index, 5 to client port and 3 to stream protocol,
that would probably cover the needs of 99.9% of the "customers".  If
there were any.  Frankly I think the issue is a red herring tossed out
by the con masquerade team.  Doing automatic state recovery would be
throwing good money after bad.  The socks*socks plumbing scheme of
terry, which seems the best candidate to date, wouldn't do this anyhow
without substantial modification.

   > "real" proxies are still rewriting packets.  They're just
   > spending a lot more to do it.  That's okay, though.

   "Real" proxies transform data in the application layer, not by 
   rewriting packets at the network layer.

Like I said, just spending a lot more to do it.  It's just a black
box.  Packets go in, packets go out.  They've been rewritten.

   > The point is to make it work, not to make it work efficiently.

   To quote Terry:  You have *got* to be kidding!

If you wanted efficiency, you'd run linux masquerade.  There's no way
an application layer proxy is going to shake a stick at masquerade
integrated in the stack.  Without looking, I bet the linux masquerade
is zero-copy.  Fortunately we're not talking about OC-12 speeds here,
as a rule.  Some very large proportion of the users will never see the
difference, so they won't care, and FBSD will provide adquate
masquerade for their purposes.







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