Preventing Users from using any desk or Team viewer

Hello,

Thank you for contacting Sophos Community!

You may use the application filter to block such applications:

https://docs.sophos.com/nsg/sophos-firewall/19.5/Help/en-us/webhelp/onlinehelp/AdministratorHelp/Applications/HowToArticles/BlockApplicationsUsingApplicationFilter/index.html#add-rules-to-the-policy

 How to allow (or block) AnyDesk when using TLS Scanning 

Thank you so much for your answer, I did follow the guide but I have few questions that are not clear.

So when I go to the application filter section I created the new filter and set it to block these apps.

then in the default action is allow?

Also when I created a firewall rule and saved it weirdly the other security feature settings were removed and my network got blocked however this is not my question, my question is when I create the rule I should add the source and destination would that mean it is also filtering my network traffic and deny everything if I put any to any and block? I am worried to do this step now. What is wrong with my rule?

I would always recommend to look into an Endpoint solution for such question first. The Endpoint has more tools to prevent such applications from starting. 

Tools like teamviewer and anydesk have methods to avoid proxies and firewalls as their goal is to always get running in every deployment. They failback to https and other methods. 

Hi,

you will also need to disable the default web exception for Teamviewer.

Ian