Hjælp til forklaring. php.

PHP kode 

 <?php
 function getip() {
 if (isSet($_SERVER)) {
 if (isSet($_SERVER["HTTP_X_FORWARDED_FOR"])) {
 $realip = $_SERVER["HTTP_X_FORWARDED_FOR"];
 } elseif (isSet($_SERVER["HTTP_CLIENT_IP"])) {
 $realip = $_SERVER["HTTP_CLIENT_IP"];
 } else {
 $realip = $_SERVER["REMOTE_ADDR"];
 }
 } else {
 if ( getenv( 'HTTP_X_FORWARDED_FOR' ) ) {
 $realip = getenv( 'HTTP_X_FORWARDED_FOR' );
 } elseif ( getenv( 'HTTP_CLIENT_IP' ) ) {
 $realip = getenv( 'HTTP_CLIENT_IP' );
 } else {
 $realip = getenv( 'REMOTE_ADDR' );
 }
 }
 return $realip;
 }
 
 //print out the ip and browser information
 
 print getip();
 print $_SERVER['HTTP_USER_AGENT'];
 ?>