How to check the amount of tcp from a proxy?

Question

linux

I buy different proxies, from different companies, and all these proxies with restrictions on tcp connections, the maximum is 512, please tell me how to check this number?
Maybe there is some kind of script or maybe a site / service, where it would be possible to load a proxy and display information about the number of tcp

Answer 1

You can try to ask directly about which ones are open - if they don’t say, then use the script to create connections until failure
upd: rewrote the answer

Answer 2

Judging by the question, you do not really understand what is at stake. therefore you don't need it. Is it worth it to bother and check what is not needed?

Answer 3

any program for ddos ​​attacks
and better Buy hosting and set your own proxy