Re: [tcpm] More TCP option space in a SYN: draft-briscoe-tcpm-syn-op-sis-02

[Bob Briscoe <[e-mail]>]

Alex,

At 16:13 25/09/2014, Zimmermann, Alexander wrote:
>Bob,
>
>Am 25.09.2014 um 05:56 schrieb Bob Briscoe <[e-mail]>:
>
> > At 23:25 24/09/2014, Joe Touch wrote:
> >> Hi, Bob (et al.),
> >>
> >> Also, I don't particularly think that putting the options at the end of
> >> the segment serves any useful purpose other than to make this option
> >> handle the option space in a different way than the default DO 
> header field.
> >
> > That's the architectural point.
> > There's also a tactical point. It should get through every middle box.
>
>but do we have not exactly the same problem w/ TCPinc. With TCPinc we have
>the problem too that a middle box doesn't see any understandable after the
>legacy TCP header (e.g. no HTTP header after TCP port 80). So, why it's
>acceptable for TCPinc but not for extending SYN option space? BTW any
>tcpdump user will love to have the options in front of a segment and not
>at the end ;-)

tcpinc is about encrypting payload. I'm interested in extending 
opportunistic encryption to TCP options, which is why I want to 
separate options into 'middlebox' and 'destination' (note: zero 
middlebox options would be valid).

Right now I'm working on a tcpcrypt-like approach, to see if I can 
get the cipher negotiation done in zero RTT (at least on a connection 
resume), so I can use it to encrypt TCP options after the payload (as 
well encrypting any payload, of course).

This will then /enforce/ the middlebox-v-destination categorisation of options.

I left any discussion of this out of syn-op-sis-02, because I'd 
rather not talk about possibilities until I know whether they are 
possible. (I guess that means I need to apologise for talking about 
possibilities on the list, but I couldn't help it, given your posting 
was so close to what I am thinking :|


Bob


>Alex




________________________________________________________________
Bob Briscoe,                                                  BT