Where are the "free" proxies on the network?

Question

Computer networks

It became interesting where free proxies come from on the Internet, why they are kept open, and most importantly, why? What is the benefit to the hoster (the one who launched it). How are they found for free proxy lists?

Answer 1

There are various options for monetizing such services from replacing advertising with your own to hijacking accounts for certain services. And of course, there is human stupidity in the form of incorrectly configured software (3proxy, nginx, apache, squid, etc.) or network devices.
How are they found? Well, they do nmap, then they check these ports with a script whether it is a proxy or not. In the logs of any public web server, requests to Google or Yandex always flicker several times a day. This is just an example of such proxy scanners.

Answer 2

Well, you need to somehow track the lovers of anonymity. Maybe you decided to go to a forbidden site there, dragging the major through the computer? Here is the benefit.