How proxychains-ng works?

Question

After reading proxychains-ng's source code, I still can't figure out how it actually work. (I am a absolute newbie to computer network.)

Does proxychains-ng redirect all network access into another network tunnel? (e.g. open a TCP connection and let the application use this connection)

The real question is that if I want to implement a proxychains-ng like application, where to start?

Thanks

Answer 1

use DYLD_INSERT_LIBRARIES and DYLD_FORCE_FLAT_NAMESPACE to use network APIs provided by proxychains other than the standard network APIs.

see main.c for the DYLD_INSERT_LIBRARIES and DYLD_FORCE_FLAT_NAMESPACE.

see libproxychains.c for the network API wrappers implementation.