How to anonymize Skype on Linux / Use anonymous skype through tor

Monday, 16th August 2010

I’ve recently worked on anonymizing as many of my applications as I could in that spirit.
I looked for a practical way to anonymize my Skype. Skype communication is so essential this days,
it’s very likely that a huge part of skype communication is being monitored by skype corp, it’s not impossiblethat some malicious installed trojan in skype would report about which IP address you’re using to connectto Skype.
Therefore proxifying skype could be a step further to at least prevent for following your skype traffic route.
Of course passing Skype traffic via tor is not a guarantee for anonimity since it’s probably very easy for Skypeowner company to keep record of Skype users, where do they people originate from, full log of people comminicationvia skype based on their user login.
As skype is a closed software and we have no access neither to the protocol specs neither to program source code, it’s almostimpossible to know if communication via skype is secure in sense of privacy.

It appeared that proxifying skype is a piece of cake and comes just to a proper instalating of Tor + polipo caching proxy and further installing proxychains

Proxychains is a rather interesting software, it’s able to carry any application TCP and DNS traffic through a proxy server (http and socks).
Therefore proxychains is able to run any program through proxy server and hence hide your real IP.

Interesting fact is that proxychains is the Unix equivalent for Window’s Freecap“Program based on universal DLL injection in alien process (works on all Windows from Win95 to Longhorn), which hooks Winsock API, redirecting connect requests to the SOCKS server.

So if you intend to proxify your Skype application on a Windows host you will have to use Wincap.

Back to the main topic of “what is the way to proxify” skype on Linux, so here is how I did it:

1. Install proxychains (available on a Debian host directly as a deb package)

debian:~# apt-get install proxychains

2. Install skype from source on Debian Testing/Unstable (Lenny / Squeeze / Sid). I personally use skype_static-2.0.0.72.tar.bz2

debian:~# cd /root

debian:/root# wget https://www.pc-freak.net/files/skype_static-2.0.0.72.tar.bz2
debian:/root# tar -jxvf skype_static-2.0.0.72.tar.bz2
debian:/root# mkdir /opt/Skype/
debian:/root# mv skype_static-2.0.0.72 /opt/Skype/

Also place a skype startup script to instruct skype that it will have to use the pulseaudio for a sound server.

Crete the /usr/local/bin/skype file.
It should contain the following

#!/bin/sh
export SDL_AUDIODRIVER=pulse;
/usr/bin/proxychains /usr/bin/linux32 /opt/Skype/skype_static-2.0.0.72/skype
#/usr/bin/torify /usr/bin/linux32 /opt/Skype/skype_static-2.0.0.72/skype

Now simply startup skype by either typing /usr/local/bin/skype from a terminal or either create a shortcut towards skypeor edit the existing shortcut added in either GNOME or KDE menus and set it to use /usr/local/bin/skype as a skype starter.

Even better proxychains can be used to proxify via a tsocks proxy any other application on your BSD or Linux.

I’ve also noticed that tor deb is also equipped with a program called torifytorify – wrapper for tsocks and tor

I’m not quite sure if torify is also able to torify skype along with the other applications for which it can be used to torify traffic, so if any of the readers of this article can give some feedback if they have tried that would be really nice 🙂

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8 Responses to “How to anonymize Skype on Linux / Use anonymous skype through tor”

  1. nursing degree says:
    Firefox 3.5.6 Firefox 3.5.6 Windows 7 Windows 7
    Mozilla/5.0 (Windows; U; Windows NT 6.1; it; rv:1.9.1.6) Gecko/20091201 Firefox/3.5.6

    Well I definitely enjoyed studying it. This tip provided by you is very practical for correct planning.
    I’m still learning from you, while I’m trying to reach my goals. I absolutely enjoy reading all that is written on your blog.Keep the posts coming. I enjoyed it!

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  2. gnulinuxarea says:
    Firefox 5.0 Firefox 5.0 Windows 7 Windows 7
    Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0

    hi there,

    isn’t just enough to install tor and proxychains and then start skype with a simple:

    proxychains skype

    ?

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    • admin says:
      Epiphany 2.30.6 Epiphany 2.30.6 Debian GNU/Linux x64 Debian GNU/Linux x64
      Mozilla/5.0 (X11; U; Linux x86_64; en-us) AppleWebKit/531.2+ (KHTML, like Gecko) Version/5.0 Safari/531.2+ Debian/squeeze (2.30.6-1) Epiphany/2.30.6

      It depends on the default configurations for proxychains (should be different for different versions and distros). Also it’s not just enough to install proxychains and proxychains skype at least not enough if you want your skype connections to go out with constantly rotating IPs and this give you some skype anonymity. Using proxychains with skype directly without tor will transfer all skype traffic only via a single IP address. This is not that secure as having the traffic being rotated via a constantly rotating IP address (offered by the Tor network).
      Hope this answers the question.

      Best!
      Georgi

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  3. gnulinuxarea says:
    Firefox 5.0 Firefox 5.0 Windows 7 Windows 7
    Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0

    thank you for the clear explanation

    if I follow your how-to I get errors, If I just proxychains skype without changing configurations it connects but I cannot communicate with contacts

    I am busy with other stuff right now but when I get the time I might come back to you with errors I get

    of course if you don’t mind 🙂

    thing is you seem to know a lot about, and also there are no many info on the web on how anonymizing skype (at least I cannot find them)

    cheers

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  4. Mckinley Kalfa says:
    Firefox 3.5.3 Firefox 3.5.3 Windows XP Windows XP
    Mozilla/5.0 (Windows; U; Windows NT 5.1; pl; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3

    Awesome post, saw you on bing and glad I clicked. Keep up the good work!

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  5. tom says:
    Unknown Unknown Unknown Unknown
    Chitika ContentHit 1.0

    Once I originally commented I clicked the -Notify me when new feedback are added- checkbox and now every time a comment is added I get 4 emails with the identical comment. Is there any way you’ll be able to take away me from that service? Thanks!

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    • admin says:
      Firefox 3.6.3 Firefox 3.6.3 Windows 7 Windows 7
      Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3

      Hi Tom,

      I’m sorry for this strange behaviour i will see for the problem and resolve it asap.

      thx.

      best,
      Georgi

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  6. ahaha says:
    Firefox 17.0 Firefox 17.0 Windows 7 Windows 7
    Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20100101 Firefox/17.0

    nor proxychain neither torsocks/torify can proxy/tunnel udp packets so skype can be deanonimized without a firewall rule that blocks udp output.

    Skype protocol is indeed closed source so none can say that the real IP is not included in the delivered UDP/TCP packets , like bittorrent for example.

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