Retrieve Internet real Time

Hi everyone, I have a great big problem. I have to do a counter, but I need to know if the time is the real time, or maybe someone changed the time.

so I thinked about retrieves time from internet, but i can't understand how to do this. I simply need the time in a format that can I understand and use for make some subtractions.

there is a way to do this? i'm going out of mind by 3 days.

hope someone can help me! thanks!