How to do or how does listen localhost work?

Question

C++ / C#

Here in some programs you can specify such a listen that it will only listen to its own machine. Is there such a function? Or is it not necessary to bind to the address 0.0.0.0? Or, after connecting, compare the client address and if it differs from 127.0.0.1, then reset the connection. I think that probably it is necessary to do bind on 127.0.0.1, but is it so?

Answer 1

I think that probably it is necessary to do bind on 127.0.0.1, but is it so?

Yes. INADDR_LOOPBACK -- there is a special macro for this address.

Answer 2

The local interface, aka localhost, has the address 127.0.0.1