Subject: [tcpm] Dual SYN and binding to an explicit port

From: Bob Briscoe <[email-masked]>
Date: Mon, 10 Nov 2014 21:24:08 +0000

Alex,

I punted this question to the list, so here's the answer...

See S.4.3. Interaction with the Pre-Existing TCP API
<https://tools.ietf.org/html/draft-briscoe-tcpm-inner-space-01#section-4.3>

Here's the relevant text:
"     Binding to an explicit port:  If an application specifies that it
       wants the TCP client to use a specific port, the Inner Space
       capability MUST be disabled, because the dual handshake has to try
       two ports.  Use of a specific port might be necessary, for example
       in a port-testing application or if the application wants to
       explicitly control all the handshaking logic of the Inner Space
       protocol itself.
"

I realise I need this text is actually too strong. The app doesn't 
need to disable Inner Space. It only needs to disable the dual 
handshake, so that it becomes a serial handshake. I.e. it tries an 
upgraded SYN, and only if the SYN/ACK comes back showing the server 
is legacy does it send a RST. Then it uses the same client port for a 
legacy SYN.

I'll change the text.

Bob

________________________________________________________________
Bob Briscoe,                                                  BT