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Re: [inbox] Re: [ Capture Skype trafic ]
From: "Exibar" <exibar () thelair com>
Date: Sun, 29 Oct 2006 21:21:45 -0500

I'm sorry, but that document outlines HOW Bluecoat can and does block Skype.
A packet or protocol anaylizer Proxy will block anything that is NOT
conforming HTTP to travel along on port 80.  Skype does not conform to HTTP
standards (for one it's encrypted) and BlueCoat will stop it.
  Yup, you can't be a moron and have every other port under the sun open on
your network too....



"STEP 4: INSTALL SSL CONTROLS ON THE BLUE COAT SG
The Blue Coat SG appliances managing application service ports for HTTP
(80), RTSP (554), MMS
(1755), etc. will drop client connections if the packets sent do not conform
to the appropriate
protocol. When Skype uses port 80, the protocol used is still Skype’s
proprietary protocol and does
not conform to HTTP and so will be blocked. The Skype application finally
attempts to use port
443, if the SSL controls are installed (part of SGOS v4.2) these packets
will also be dropped as
there is no SSL certificate exchanged between Skype nodes. Therefore, any
attempt to establish a
Super-node connection through these service ports will be unsuccessful, as
the connection is nonconforming to standards."



-----Original Message-----
From: Tyop? [mailto:tyoptyop () gmail com]
Sent: Friday, October 27, 2006 2:19 PM
To: Exibar; full-disclosure () lists grok org uk
Subject: [inbox] Re: [Full-disclosure] [ Capture Skype trafic ]


On 10/27/06, Exibar <exibar () thelair com> wrote:
From: "Tyop?" <tyoptyop () gmail com>
All is in the mail's subject.
I need to match this crazy-encrypted-random trafic,
to destroy it (I think I'm not alone to need informations on this
product).
I've found some work on the BlackHats slides,
but skype updates..
use a packet analyzer proxy....  bluecoat comes to mind as one
that works
quite well...

http://www.bluecoat.com/downloads/whitepapers/BCS_controlling_skype_wp.pdf
Bluecoat doesn't match the packets, sorry.

quote:
It is also recommended that enterprises block downloads of URLs ending
with "skype.exe". This will prevent new Skype software from being
downloaded to enterprise machines.

This is very funny. ^-^

--
Tyop?
"Please excuse my english."




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