From: Adam Shostack <adam@lighthouse.homeport.org>
Date: Wed, 13 Mar 1996 04:13:53 +0800
To: gary@kampai.euronet.nl (Gary Howland)
Subject: Re: FCC & Internet phones
In-Reply-To: <199603121049.FAA20806@bb.hks.net>
Message-ID: <199603121432.JAA06480@homeport.org>
MIME-Version: 1.0
Content-Type: text


Gary Howland wrote:

| Adam Shostack wrote:
| > Loren James Rittle wrote:
| > | >Most
| > | >presumably use a mix of a UDP data connection and tcp for control
| > | >functions.
| > |
| > | OK, everything after the IP header is encrypted.  I don't even know
| > | which protocol is in use.
| >
| >         Are you willing to play Mallet?  Drop IP packets, and look for
| > duplicates.  Those are TCP.  (IPSEC might handle this, but I bet there
| > will be broken implementations that save time by resending.)
| 
| Are you saying UDP protocols don't retransmit un-acked packets?
| If not, then you can't be sure the duplicates are TCP.

Err, yes.  Thats the point of UDP; its unreliable and has no
acknowweldgement.

"The User Datagram Protocol uses the underlying Internet Protocol to
transport a message from one machine to another, and provides the same
unreliable, connectionless datagram delivery semantics as IP."
(Comer, 11.3)

Adam


-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume