Nate Duehr wrote:

> On May 31, 2007, at 5:21 AM, Russell McMahon wrote:
> 
>> Skype is an aggressive secret sharer of your resources. [...]
>
> [...] They did seem to switch over to a model where they provide some
> very high bandwidth servers for this purpose instead of using random
> Skype nodes "near" you on the Internet when they got bigger, but I think
> the functionality is still there as a fall-back.  I haven't monitored
> Skype traffic for a while now to see what it's been up to lately. 

I have, and I see it having typically between 5 and 10 connections open,
with traffic spices about every 20 seconds that average in the range of
hundred bits/sec.


>> [...] but as it makes every effort to avoid or fool the normal
>> monitoring systems, any claims as to what it does or doesn't do should
>> be judged with care and after taking note of the tools and credentials
>> of the claimants.
> 
> It's not THAT hard to spot it... you do have to have knowledge of how  
> your firewall/network is configured and know where and how to look.

Depends on what you want. Every normal software firewall will spot it; it
doesn't do things that much different from any other network application in
this respect. And if you shut down other traffic and just observe the
overall traffic through your router, you can see that this is it. No
special tools necessary, not even much knowledge about the network
configuration; just plain vanilla tools. (Without that knowledge they
obviously won't give you the certainty that you did find everything, but
chances are you did.)


>> You have the ability to make a supernode voluntarily and may or may not
>> have the ability and right to not do so.
> 
> Yep.

Are there any reports of supernodes behind a NAT router? So far, most of
the information out there that says that supernodes need Skype on a
routeable IP address -- which excludes machines that are behind a NAT
router. Which then would mean that it is relatively easy to make sure
you're not going to be a supernode: get behind a NAT router. Besides, there
are reports that people could stop Skype becoming a supernode (even when on
a routable address) by simply blocking incoming connections to it on the
selected port. 


>> If you don't want to use Skype on a given occasion you may elect not to
>> run it, but this is no guarantee that it will not want to use you (or
>> your system) and choose to run you (or your system). If it does do so
>> don't expect it to tell you and don't expect to be able to easily
>> determine that it is doing so.
> 
> On Windows perhaps.  Pretty easy to find it doing things on any other
> (sane) operating system where the sysadmin can easily see resource
> utilization.  Windows mistakenly allows applications to "hide" what
> they're doing a little more, but it's still easy to spot Skype behaving
> badly on Windows with the right tools, of course.

I don't know what other people do, but Skype doesn't hide at all on my
(Windows) system. When it is running, it's visible in the system tray, in
the Windows Task Manager, in any (usable) software firewall, in any sort of
minimum capability process or network monitor. And when you exit the
application (as opposed to just close the main window, which leaves the app
running with a tray icon showing this -- the same as so many other tray
applications do), it /is/ gone. (Other than e.g. the Windows networking,
which I personally consider a much bigger security risk when connected
directly to the internet than Skype.)

Gerhard

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