What's the source of public proxies?

I was wondering, what's the source of public proxies? Are they coming from botnets? Or maybe leaked private proxies?
How would I create my own list without scraping the web for proxy lists (are there any alternatives to port-scanning which I guess is illegal)?

ive port scanned on my isp 6 yrs
no issues... you only need the ip blocks
to scan and your done

Private proxies must be used with username and password, so it's not leaked private proxies.
I think there are some opened servers around the web, and most public proxies are involuntary.
All public proxies comes from scan at the beginning. I can be wrong...

Beny

There are people which might benefit from running open proxies. Nobody is going to do something "for free". There are people who submits their proxies to public lists because there are still people which use them for surfing and since they are stuffed with ads most of the time, they are probably earning some money with it. Or it is possible to just steal peoples credentials etc.

But yes, I was also wondering, if there are still people who actively scan for proxies. I tried once on my VPS, but then I had to stop since few admins of servers which I scanned complained to my VPS provider and they wanted me to stop doing that.

If there are someone who could recommend any good "blackhat" VPS provider which is ok with proxy scanning, I would be glad to order with his affiliate link.

Same questions... Where do public proxies come from? Are they cracked computers?

And is port scanning legal?

in my corner of the world the problem with proxy scanning is that ISP's know when you are doing so and you can end up with you internet speed trimmed down or sometimes down.
I do scan a lot from my own machine, but try online checkers.
proxypirate.uv.ro
checker.freeproxy.ru/checker/

Gathering proxies tho is a matter of smart google-ing.

You will need port scanners with a very good internet speed & you will also need ip ranges to scan them through.