[e2e] Can we revive T/TCP ?

Joe Touch touch at ISI.EDU
Fri Mar 24 17:37:46 PST 2006

Bob Braden wrote:
> At 07:31 PM 12/26/2005 +0100, Michael Welzl wrote:
>> Hi everybody,
>> Here's something that I've had on my mind for quite a while now:
>> I'm wondering why T/TCP ( RFC 1644 ) failed. I mean, nobody seems
>> to use it. I believe someone explained this to me once (perhaps even
>> on this list? but I couldn't find this in the archives...), saying that
>> there
>> were security concerns with it, but I don't remember any other details.
> As the designer of T/TCP, I think I can answer this.  There are three
> reasons, I believe.
> (1) There are very few situations in which single-packet exchanges
>     are possible, so T/TCP is very seldom a significant performance
>     improvement.  But it does have significant complexity.
> (2) Since the server is asked to do a perhaps signficant computation
>     before the 3WHS has completed, it is an open invitation to
>     DoS attacks.  (This would be OK if you could assume that all
>    T/TCP clients were authenticated using IPsec,)

Not just computation - also storage (of the data in the SYN).

But I had thought the major issue was more with the sequence number - as
discussed (among others) in Hannum as posted to the TCP-IMPL WG in 1996:


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