full-disclosure - Re: [inbox] Re: [ Capture Skype trafic ]

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Date: Sun, 29 Oct 2006 21:21:45 -0500
From: "Exibar" <exibar@...lair.com>
To: "Tyop?" <tyoptyop@...il.com>,
	<full-disclosure@...ts.grok.org.uk>
Subject: Re: [inbox] Re:  [ Capture Skype trafic ]

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 Skypes
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@...il.com]
> Sent: Friday, October 27, 2006 2:19 PM
> To: Exibar; full-disclosure@...ts.grok.org.uk
> Subject: [inbox] Re: [Full-disclosure] [ Capture Skype trafic ]
>
>
> On 10/27/06, Exibar <exibar@...lair.com> wrote:
> > From: "Tyop?" <tyoptyop@...il.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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