[e2e] Can we revive T/TCP ?
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
>> 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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