Re: Moving Forward with Regularizing Port Numbers

Text item: 

The discussion so far is all based on the assumption that the protocols 
that want to be enhanced with TLS/SSL all have current port assignments 
below 1024.

We are working on securing H.323 (A/V Conferencing) with TLS/SSL, and 
will need port assignments for the SSL-enhanced protocol(s), but I 
expect them to be Registered Ports above 1024.

BTW (as per my previous posting on the subject), the same port can be 
used for secure & non-secure versions of a protocol as long as:

  a) there is a negotiation/discovery mechansim outside the protocol to  
     determine the use of security, or
  b) the implementation can deterministically differentiate any          
     application message from the ClientHandshake message.

Method b) is fraught with difficulty, including the fact that the 
application will be at the mercy of how the Operating System implements 
TLS/SSL, since there would have to be collusion between the two when the 
application detects the ClientHello (or the TLS/SSL layer does not 
detects ClientHello - depending on who sees the message first).

An Operating System may not be willing to trust the implied assertion by 
an application that its protocol can be differentiated....who knows 
where a false assertion would take it....


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Subject: Moving Forward with Regularizing Port Numbers
From: Christopher Allen <>
Date: Thu, 6 Feb 1997 03:36:53 -0800
Organization: Consensus Development Corporation <>
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