I could not find an explanation on how it works. How could you possibly know when I am opening your PDF file ? I presume opening your PDF file will trigger some

I could not find an explanation on how it works. How could you possibly know when I am opening your PDF file ? I presume opening your PDF file will trigger some kind of http / socket request to a site that you control. so how would you control companies'firewall ? and/or any other settings that could prevent my pdf reader to go online