tele
Blocking application access to the Internet.
firejail --net=none app_name
Blocking access to folders except one.
firejail --noprofile --whitelist=/path/to/folder app_name
Video
Firejail Sandbox - Firejail HowTo: Disable Network Access
The default launch of the application in the sandbox
From root account
Turn on - creating symbolic links.
firecfg
Turn off - removing symbolic links
firecfg --clean