How to organize a fast forward of thousands of proxies (socks5, https) to other proxies on local ports (preferably with authorization)?

Question

linux

Good day, dear ones!
There is a task to make forward to external proxies (to which we have access only via IP vps. Some of them are with authorization, others are without.
Which tool is best suited for simple traffic redirection?
We wanted to use SQUID, but the standard config does not fit, everything rests on ports. It is necessary to configure and assemble the package.
But this is not the point, but in general that it seems too voluminous to us.
Maybe there is something simple and sharpened for our purposes?
Well, of course, at least basic authorization was supported for connecting to ports on the VPS, that will forward without using third-party solutions
.

Answer 1

In 3proxy, the configuration is something like this:

log
auth strong
fakeresolve
users user1:CL:pass1 user2:CL:pass2 user3:CL:pass3

allow * 
parent 1000 socks5+ socksip1 socksport2
socks -p10001
flush

allow * 
parent 1000 socks5+ socksip2 socksport2
socks -p10002
flush

allow * 
parent 1000 socks5+ socksip3 socksport3
socks -p10003

forwards 10001 to socksip1:portip1, 10002 to socksip2:portip2, 10003 to socksip3:portip3, requires login/password authorization on all ports.
If the parent proxies are http, then you need to use http instead of socks5+, if the proxies themselves need http, then you need to use proxy instead of socks.
But if you run into ports, then this cannot be solved at the proxy level, you need to tune the system, there are recommendations here.