How to drop or block Skype connections with your gateway firewall

Written by Gionatan Danti on . Posted in Howto

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Conclusions

Well, conclusions are going to be short this time ;)

The explained approach to block and drop authentication requests is a viable one to block Skype connections, specially if you are short of UTM appliance.

However, I want to do two important recommendations:

  1. remember that Skype hosts can change, so if you feel that someone is using Skype despite your policies, use a packet sniffer to check hosts list; 
  2. it is possible that some other, legitimate, non-Skype hosts went included into my list. So be aware of false positive and, if some services stop working after you added these policies, carefully watch your firewall's log to immediately find these legitimate hosts. 

I hope that this article will be useful. If you want, you can contact me using the comment system or by writing at This email address is being protected from spambots. You need JavaScript enabled to view it.

Have a nice day!

Comments   

 
#1 Akiv 2013-07-23 14:24
This was very helpful. I had to add some more ip ranges tracked through firewall. So far seems good.
 
 
#2 Gionatan Danti 2013-07-23 14:41
I'm glad to know that my suggestion worked for you :)

If you want, you can suggest us (via this comment system) the additional tracked IP ranges.

Thanks.
 
 
#3 Daniel 2013-10-14 21:42
This article here summarizes and quickly explains (what this article explains in detail)

Scroll to the bottom of the first page for instructions on how to do this!

http://forums.anandtech.com/showpost.php?p=35604779&postcount=11
 
 
#4 Yvonne 2015-05-22 15:27
Appreciate presenting this to everyone.
 
 
#5 Randy 2016-05-04 23:57
How do I block mobile devices from using Skype? This method only works for laptops and desktops. My iPhone and iPad with the Skype App works with this in effect.
 

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