[LINK] CNN, Octoshape and Obama

Kim Holburn kim at holburn.net
Mon Feb 9 19:53:26 AEDT 2009


On 2009/Feb/09, at 2:47 AM, Richard Chirgwin wrote:

> Karl Auer wrote:
>> On Mon, 2009-02-09 at 08:50 +1100, Roger Clarke wrote:
>>
>>>      But even that is sufficient to enable informed consent.
>>>      e.g.
>>>      "the app will use some of your disk-space and bandwidth to  
>>> deliver
>>>      parts of the video and audio stream to other end users of the
>>>      Software"
>>>
>>
>> I don't know for sure, but it seems to me that the only way Skype can
>> work is to use (abuse?) the good offices of people with non-NAT
>> connections. Yet I know I was never informed (or at least not in a  
>> way
>> that I noticed) about that possibility - although since my client is
>> NATted maybe there was no need.
>>
>> Regards, K.
>>
> I think, from reading various analyses of the Skype protocol, that  
> it's
> designed to work around NAT. It has, I think, a proprietary
> equivalent to STUN, so that it can traverse the firewall.

Yeah it can get around firewalls in ways other VOIP protocols can't.   
But it can't open conversations to boxes behind firewalls, although I  
suppose it could ask them to initiate those conversations.  So far it  
hasn't done that AFAIK.

But any open box (ie without a firewall, that will accept incoming  
connections) with sufficient resources ie bandwidth, cpu, etc will  
become a supernode routing other skype traffic.

Skype depends on this.

Oh and the Chinese have developed their own skype clients which can,  
probably, decrypt skype traffic and possibly, with suitably placed  
supernodes, send interesting conversations to China.


> Eg:
> <http://www1.cs.columbia.edu/~library/TR-repository/reports/reports-2004/cucs-039-04.pdf 
> >
>
> Cheers,
> RC
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-- 
Kim Holburn
IT Network & Security Consultant
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