How to check that a python script is not sending information to the outside?

Question

Python

I ordered the program, launched it, it performs the stated actions.
How to make sure that it does not leak any data outside?
Well, how can she forbid it without being convinced?

Answer 1

You can, run it as a special user (new), you can block it with iptables.
iptables -I OUTPUT -m owner --uid-owner user -j DROP

Answer 2

if the script is small, then you can try to figure it out, find all the commands or functions, such as

• urllib.request.urlopen(url_0).read().decode("utf-8")
  after these commands, append the url output to a file in the form of logs, or it is easier to output to the console - print (url)