How does a website know your ip address? [closed]

Question

When I visited the website http://myipaddress.com/what-is-my-ip-address/

I checked the request header information. No where does it include my ip address. So how is the web server able to determine my ip address? I know that any web server has access to this information. But if its not there in the HTTP request, how do they get it?

Answer 1

You're connecting to the server and sending it an HTTP request. The server replies with a page. To do that, it has to know where to send the reply to. That information is automatically available from the socket connection (i.e. from a lower level than HTTP), so it doesn't have to be repeated in the request headers.

Edit: If you want to know more about how the web server does this, see the accept function. When a connection comes in, the web server calls accept, which automatically provides it with the address of the other side.