I would like to know how to stop telegram from updating Message before authentication in the situation below;

Question

Hi I would like to know how to stop telegram from updating Message before authentication in the situation below; 
 I have a firewall device model XG135 frameware 16.01.2 
 For connecting our users in order to use internet they are redirected to a captive portal with usernames and passwords that needs authentication as well But users can use there telegram account on there cell phones without any problem, and in this way we have unidentified internet usage on our firewall reports 
 I would like to know how to stop telegram from being used by the users before authenticating the username and password 
 Thanks for the help

sachingurung · Answer

Hi Mohsen, 
 First, how are the mobile users authenticated I believe the captive portal login are done on laptops and desktops but, do you follow the same login for mobile users too? 
 Next, take a packet capture on a particular source IP of a mobile phone and use telegram. Check which FW-ID does the traffic flow through. Send a picture of the inside of this rule. 
 If telegram application is available in the application control list add it in the policy and keep the action as block. 
 Thanks

sachingurung · Answer

Hi Mohsen, 
 Show me a picture of inside configuration in the FW rule ID 1 and make sure micro app scanning is marked in the application filter policy. Refer the post here . 
 Thanks

lferrara · Answer

Hi All, 
 I tried today to block Telegram on my mobile at home, forcing user to authenticate. 
 
 A top rule where LAN to WAN (only my Mobile) is allowed to use HTTP and HTTPS (scan http & https traffic) and where Application filter (allow all but blocking only Telegram) is applied 
 Match know users and show captive portal to unknow users is checked 
 Captive portal is configured to display is configured to display link under Authentication > Services 
 
 With this settings, Telegram is blocked before the authetication and after. 
 Make sure to enable Micro-App scanning and HTTPS decrypt and scan. 
 Regards