[e2e] ISN regeneration when Stateless SYN cookies are used

gangadharan annapurna nallu17 at hotmail.com
Thu Oct 18 10:55:06 PDT 2001


However,

The problem is lets say U send a SYN which falls within the receive
window and the connection is RST.  Now if we do implement a stateless SYN 
cookie then what exactly must be done to avoid that RST, without
keeping any state.

If we can regenerate the same ISN again, then there is no problem.
OR if we make sure that the next ISN that is generated does not fall within 
the receive window we are OK.

How do we solve even one of these issues ?

REMEMBER No State is to be stored.  Becoz if we store a state, we can 
regenerate the ISN.

Naren



>From: "John R. LoVerso" <john at loverso.southborough.ma.us>
>To: Michael B Greenwald <mbgreen at dsl.cis.upenn.edu>
>CC: mahesh at erg.abdn.ac.uk, gangadharan annapurna <nallu17 at hotmail.com>,   
>end2end-interest at postel.org
>Subject: Re: [e2e] ISN regeneration when Stateless SYN cookies are used
>Date: Thu, 18 Oct 2001 12:15:16 -0400
>
> > No, I meant a SYN with a sequence number that's within the valid window
> > (which is what the original question was asking).  It's not a duplicate.
>
>You are exactly correct.  See the bottom of page 71 of RFC793.
>http://www.ietf.org/rfc/rfc0793.txt
>
>John


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