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Skype's Network Ditches P2P Tech for Linux Boxes

By - Source: Ars Technica | B 15 comments

The new Skype network has fewer Linux-based supernotes that now use grsecurity to fend of hacking attacks. Updated with clarification from Mark Gillett, CVP of Skype Product Engineering & Operations.

Microsoft has reportedly done away with the peer-to-peer client machines that have powered Skype's VoIP network over the last nine years. Instead, Skype now uses thousands of Linux-based servers that have been "hardened" for the most common types of hack attacks.

Skype's network overhaul was discovered just weeks ago, but the switch out is believed to have taken place several months back. Ultimately this new network is expected to prevent outages from happening again, giving Microsoft better control over Skype's system as a whole.

"The number of supernodes has dropped from 48k+ to 10k+, and all the supernodes are now hosted by Microsoft/Skype," reports Immunity Security's Kostya Kortchinsky on his personal blog. "Promotion of random eligible nodes to supernodes has stopped (through the setting of the global Boolean 33h). Ironically, those remaining supernodes run on grsec'ed Linux boxes (I hope Spender gets a sizeable donation from Microsoft). They can host a considerable amount of clients, ~100,000."

This explanation essentially means the Skype network has been reduced from over 48,000 supernodes down to over 10,000, and now there's no way that an individual user can become a supernode. The remaining supernodes are also running a version of Linux using grsecurity, the latter of which is a collection of patches and configurations designed to make servers more resistant to attacks.

Even more, these Microsoft-hosted machines are capable of accommodating significantly more users than before. Previously supernodes on the old system could handle around 800 users simultaneously, but now they can each play host to around 4,100 users with a theoretical limit of 100,000 simultaneous users. That said, the number of supernodes in the Skype network has decreased while the user capacity has increased.

"It's pretty good for security reasons because then you don't rely on random people running random stuff on their machine," Kortchinsky told Ars Technica. "You just have something that's centralized and secure."

Skype has seen nothing but growth since its debut back in 2003. However its steepest spikes have occurred within the last two years. From October 2010 to March 2011, Skype saw an additional 6 million concurrent members, but then saw seven months of flatlined growth. Then in January 2012, Skype saw an insane 104-day 9 million spike, averaging 95.5K additional signed-in users daily. Skype now plays host to over 41 million users during peak hours.

The news surrounding Skype's new network arrives after Microsoft said it was investigating reports that a modified client will allow users to see the IP address of anyone on Skype whether they're friends or strangers. "This is an ongoing, industry-wide issue faced by all peer-to-peer software companies," a Skype representative said. "We are committed to the safety and security of our customers and we are takings measures to help protect them."

Microsoft scooped up Skype back in October 2011 for a meaty $8.5 billion. Since then, Skype has arrived on Windows Phone and Sony's PlayStation Vita. There are also signs that Microsoft plans to introduce Skype as a Web app for browsers later this year, and that the popular VoIP service is finally headed to the Xbox 360 console.

UPDATE: Mark Gillett, CVP of Skype Product Engineering & Operations, sent over a little clarification about the network update, saying that it has not changed the underlying nature of Skype’s peer-to-peer architecture.

"As part of our ongoing commitment to continually improve the Skype user experience, we developed supernodes which can be located on dedicated servers within secure datacenters," he told Tom's in an email on Wednesday. "This has not changed the underlying nature of Skype’s peer-to-peer (P2P) architecture, in which supernodes simply allow users to find one another (calls do not pass through supernodes).  We believe this approach has immediate performance, scalability and availability benefits for the hundreds of millions of users that make up the Skype community."

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Top Comments
  • 18 Hide
    RazorBurn , May 2, 2012 12:47 PM
    Microsoft will use Linux Servers?? Does anyone see the irony in this??
  • 18 Hide
    scythe944 , May 2, 2012 1:31 PM
    RazorBurnMicrosoft will use Linux Servers?? Does anyone see the irony in this??


    ... they couldn't afford all of that pesky licensing! oh... wait.
Other Comments
  • 3 Hide
    drwho1 , May 2, 2012 12:40 PM
    "Skype now uses thousands of Linux-based servers that have been "hardened" for the most common types of hack attacks."

    On other news, attackers have move into newer less common attacks,
  • 18 Hide
    RazorBurn , May 2, 2012 12:47 PM
    Microsoft will use Linux Servers?? Does anyone see the irony in this??
  • 18 Hide
    scythe944 , May 2, 2012 1:31 PM
    RazorBurnMicrosoft will use Linux Servers?? Does anyone see the irony in this??


    ... they couldn't afford all of that pesky licensing! oh... wait.
  • 3 Hide
    matt_b , May 2, 2012 1:49 PM
    RazorBurnMicrosoft will use Linux Servers?? Does anyone see the irony in this??

    I was thinking the exact same thing through the read. Irony is part of it, but more importantly, should I now have less faith in their Windows Server OS?
  • 4 Hide
    yumri , May 2, 2012 2:10 PM
    um matt_b you probably should if the company doesn't use its own OS to do sever side operations there is a flaw in it that they were not able to fix and thus you probably shouldn't use it as due to that flaw what ever it might be
  • 7 Hide
    killerb255 , May 2, 2012 3:02 PM
    ...guess Microsoft doesn't eat their own dog food...
  • 5 Hide
    Benihana , May 2, 2012 5:46 PM
    Hmm... Linux or Windows, which to use... As a man with a brain, Linux definitely is appropriate. As a die-hard Microsoft fan, I'll just use what they use.

    Linux it is!
  • 5 Hide
    _TuxUser_ , May 2, 2012 6:13 PM
    RazorBurnMicrosoft will use Linux Servers?? Does anyone see the irony in this??


    Microsoft been employing Linux and BSD admins for a long time and one of the largest Linux staff employer and even have their own Linux development department, not always just making things to happen but also copy GPL licensed software and then sell it with a Microsoft EULA.
  • 2 Hide
    mayne92 , May 2, 2012 6:27 PM
    RazorBurnMicrosoft will use Linux Servers?? Does anyone see the irony in this??

    Well said!
  • 0 Hide
    mightymaxio , May 2, 2012 7:28 PM
    Linux servers have a purpose the same as microsoft servers do, its important to play on both sides of the fence since that way they can market products to both.
  • -3 Hide
    sandmanwn , May 2, 2012 9:30 PM
    Who cares what its running on...
    Can I finally get skype on something other than a verizon phone without hacking my provider code???????
    I can't install it on half the devices I have. Need to increase the installation base.

    Its a great tool that is still very limited.
  • 0 Hide
    alidan , May 2, 2012 10:42 PM
    id guess that the linux thing is compatibility reasons right now, reducing the servers and increasing the amount they can handle could be a stopgap between a full transition...

    keep in mind, skype is a service that if it blacked out or failed for a lenghy period of time (a full server os switch) could kill the product, even if it came back better than before.
  • 0 Hide
    Benihana , May 2, 2012 11:31 PM
    sandmanwnWho cares what its running on...Can I finally get skype on something other than a verizon phone without hacking my provider code???????I can't install it on half the devices I have. Need to increase the installation base.Its a great tool that is still very limited.

    Haha, very true. And most people care probably because it's akin to Apple using Windows NT servers for it's iTunes user authentication servers, or Microsoft using MacOS X servers for it's Xbox network backbone. If your product really is as badass as you hype it to be, then why do you need some CrApple or MS_BS to run it on? The real badass companies make their own products and use it. Like Google using GWS for it's web serving needs. :) 
  • 0 Hide
    maddy143ded , May 3, 2012 3:14 AM
    Theyuse Linux because it is more ideally built for that specific task, and instead of building up a brand new OS from ground up they took a shortcut and customized Linux kernel for themselves...
  • 1 Hide
    TheKurrgan , May 3, 2012 4:24 AM
    The guy in charge of Skype was only allowed to use the 2012 version of Windows server, no other..
    In that light, I dont see where he had a choice..