Why has this not been done?

[Niall Sheridan]

dave walker wrote:
> So when drinking some beer with friends we sometimes come up with crazy
> ideas that should be done, however we normally figure out why it is a
> bad idea.  However, I have had an idea stuck in my mind for about 2-3
> months and can not figure out why it has not yet been done.  I know
> there is randomness in the initial sequence number for TCP packets.  But
> what about making the rest of the packets random sequence.  (read my
> post before saying you can't have random sequence numbers)

There's a good reason to have consecutive numbers. It's called the "I
can tell which packets I have received and which packets I have not" reason.
> 
> I know there is a lot of talk going about with network security and all,
> and I am not sure if it is relevant to this idea that I have.  I know
> most talks of security are with phishing and what have you.  I thought
> of a hack for TCP that would deter man-in-the-middle / hijacking
> attacks.  I wrote a small thing on it here:
> http://blogbp.com/archives/2005/07/security_throug.php

And how exactly do you tell the far end what equation to use without it
being subject to a MitM attack?
> 
> The only problem we see with it, is the potential for it taking time to
> come up with (int)1 to (int)1 equations.  So if there is a better reason
> on why this has never been done I would love to know.  I am not the best
> at TCP Protocol programming, and don't really understand what happens at
> that level.
> Thanks,

It has never been done because it has the unfortunate side effect of
killing TCP in the face.

~ Niall