title: Alternative to $_SERVER['REMOTE_ADDR'] in php
body: <p>Is there any alternative to the $_SERVER['REMOTE_ADDR']. Which returns the ip address of the computer accessing a site.
  I'm trying to search about same external ip assigned by router, and got into this:
  <a href="https://stackoverflow.com/questions/1982222/how-do-two-computers-connect-to-same-external-address-through-nat">How do two computers connect to same external address through NAT?</a>
  And found out that the same external ip is assigned if the computers are connected to the same modem. 
  I'm creating a simple login program in php which uses $_SERVER['REMOTE_ADDR'] to determine if a user is already logged in somewhere else in the same network. And this won't actually work if those computers are connected to the same modem through the router.</p>