Re: [Tsvwg] WGLC for Port Randomization starts now (April 1st)

Joe Touch <touch@ISI.EDU> Thu, 28 May 2009 15:10 UTC

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Date: Thu, 28 May 2009 08:11:42 -0700
From: Joe Touch <touch@ISI.EDU>
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To: Randy Stewart <randall@lakerest.net>
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Cc: "James Polk (jmpolk)" <jmpolk@cisco.com>, "Anantha Ramaiah (ananth)" <ananth@cisco.com>, tsvwg <tsvwg@ietf.org>, mallman@icir.org, Fernando Gont <fernando@gont.com.ar>
Subject: Re: [Tsvwg] WGLC for Port Randomization starts now (April 1st)
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Randy Stewart wrote:
> Joe:
> 
> In-line..
> 
>...
>> Basically for BSD we take a v-tag used in a connection.. call it 'X', and
>> we place just the tag 'X' into a "timed-wait" cache for 2MSL. There is no
>> restriction on the socket here.. just the tag 'X' will not be used again
>> with this socket.

...
>> So basically the socket/port and peer socket/port is re-used right away
>> with
>> the restriction being that the vtag 'X' cannot be used.
> 
>> Hope that clears up the issue  :-)

Yes, but it also underscores my concern. What you did was basically:

	- increase the space available to a single service from
	a single IP address
		going from TCP's 16 bits (max) of source port to
		48 bits of source port + vtag

	- *decrease* the space available for different
	services from different IP addresses
		going from TCP's 32 bits of address +
		16 bits of source port + 16 bits of
		dest port (64 bits) down to only 32

Joe
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