Block file transfer via skype

Application Control contains two Application Sensors for Skype: one appears to cover the actual peer-to-peer stuff and the other one is listed as " Skype.Communication" . You could try creating an app sensor that blocks one and another app sensor that allows the other. Whether this will work the way you want it I do not know.

Skype is very evasive. I allow Skype in my environment, but disallow all other IM and P2P. The logs frequently show Skype traffic that is being blocked because it' s being classified as other applications that I have blocked. But Skype always works anyway. If Skype can' t find it' s normal ways out, it will use port 443 SSL only to get out. I don' t use deep-packet SSL inspection in my environment; using that may improve your chances at successfully controlling Skype.

There' s no more granular control in Skype. As the protocol is encrypted and there' s no proxy for it. Maybe in the future when Microsoft opens up the protocol.

Tcp traffic in skype after 3.x are NOT able to decrypted if sniffer in the middle. and they also prevent attack of man in the middle, so detect file transfer by decrypt is not working.

A little late to this, but I have the answer for blocking File Transfers in Skype. Unfortunately it' s a registry key that needs to be added, and not a FortiGate setting. https://support.skype.com/resources/sites/SKYPE/content/live/DOCUMENTS/0/DO5/en_US/skype-it-administrators-guide.pdf Here' s the administrator' s guide, it works with the most recent 6.1 release as well (Appendix 1 has the configurable policies). So in example, to block file transfers, you will need to add this registry key: HKEY_CURRENT_USER\Software\Policies\Skype\Phone, DisableFileTransfer, REG_DWORD = 1 You will likely have to add the Skype\Phone hive, so it' s best to do this via GPO or a .reg file. ...And I can' t find any mention on doing a similar function on Macs, sorry.