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Wireshark-users: Re: [Wireshark-users] Same SEQ number but different ACKs

From: Sake Blok <sake@xxxxxxxxxx>
Date: Mon, 14 Apr 2008 00:29:28 +0200
On Sun, Apr 13, 2008 at 05:28:01PM -0400, Sheahan, John wrote:
> 
> My question is, after doing some research on Encryption Alert (21), it
> seems to imply some kind of fatal error yet you say that the ssl
> connection gets closed cleanly?

"Encrypted Alert" means that a ssl alert has been sent while the
session is already being encrypted. One of the alerts is the 
"Close Notify" message, which tells the other side that it wants 
to tear down the SSL session. This is called a clean ssl shutdown
opposed to just closing the TCP session without properly tearing
down the SSL session (which is called an unclean ssl shutdown).

Since the Encrypted Alerts appear just before the TCP/FIN's I just
assume that they are in fact of the type "Close Notify". 

Cheers,
    Sake