[Dshield] Question on Skype

John B. Holmblad jholmblad at aol.com
Sat Feb 18 23:41:44 GMT 2006


Richard/Kenton,

here is a not-too-old analysis of how the Skype protocol/service 
operates based on some Ethereal based sleuthing  by the researchers who 
published this paper:

    
http://www1.cs.columbia.edu/~library/TR-repository/reports/reports-2004/cucs-039-04.pdf


I have found that if all you require is outbound call origination then 
you can still use the Skype service with a firewall that blocks all 
inbound TCP/UDP. Furthermore, if you purchase the Skypeout prepaid 
service, then you can make calls to the traditional telephone networks 
and not have to be concerned about becoming a supernode. It also works 
just fine over WIFI and I have tested it on a PDA with an 802.11 
interface. Netgear will soon have a skype VOWIFI handset.  Here is the 
url to a www page at the Netgear www site on the product:

   
    http://tools.netgear.com/skype/
   

Best Regards,

 

John Holmblad

 

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Kenton Smith wrote:
> OK, teminology aside, I new I had read something
> recently that had an excellent summary of the
> implications of using Skype, including security. P2P
> is an issue he lists in there.
> "Like KaZaA, Skype is based on peer-to-peer
> technology: instead transmitting all voice calls
> through a central server, as Vonage does, Skype
> clients seek out and find other Skype clients, then
> build from these connections a network that can be
> used to search for other users and send them
> messages."
> and
> "Third, because Skype is mostly a peer-to-peer system,
> the overall security can be affected by third parties
> that are in the network (but that  are unknown to
> those in a particular phone conversation)."
> Entire paper is here:
> http://www.tacticaltech.org/files/Skype_Security.pdf
>
> It addresses a number of issues surrounding Skype
> security.
>
> Kenton
>
> --- Valdis.Kletnieks at vt.edu wrote:
>
>   
>> On Fri, 17 Feb 2006 12:02:59 EST, Kenton Smith said:
>>     
>>> My concern with Skype is that it is a P2P
>>>       
>> technology.
>>     
>>> As far as I know that means that your machine
>>>       
>> could be
>>     
>>> being used as a node in the network even if you
>>>       
>> aren't
>>     
>>> using it.
>>>       
>> P2P simply means 'Peer To Peer' - meaning that the
>> machines that
>> want to talk do so directly, rather than the more
>> usual 'client server'
>> model (where if 2 arbitrary machines wanted to
>> communicate, they'd do
>> so by sending to a central server, which would then
>> forward to the other
>> machine).
>>
>>     
>
>
>
>     
>
>     
>         
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