Six Methods to Retrieve the Client IP Address in PHP

This article introduces six practical PHP approaches for retrieving a client's IP address, each using different server or environment variables to handle direct requests, proxy headers, and CDN information.

Method 1:

function getip() {
  static $ip = '';
  $ip = $_SERVER['REMOTE_ADDR'];
  if (isset($_SERVER['HTTP_CDN_SRC_IP'])) {
    $ip = $_SERVER['HTTP_CDN_SRC_IP'];
  } elseif (isset($_SERVER['HTTP_CLIENT_IP']) && preg_match('/^([0-9]{1,3}\.){3}[0-9]{1,3}$/', $_SERVER['HTTP_CLIENT_IP'])) {
    $ip = $_SERVER['HTTP_CLIENT_IP'];
  } elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && preg_match_all('#\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}#s', $_SERVER['HTTP_X_FORWARDED_FOR'], $matches)) {
    foreach ($matches[0] as $xip) {
      if (!preg_match('#^(10|172\.16|192\.168)\.#', $xip)) {
        $ip = $xip;
        break;
      }
    }
  }
  return $ip;
}

Method 2:

<?php
error_reporting(E_ERROR | E_WARNING | E_PARSE);
if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]) {
  $ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"];
} elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"]) {
  $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"];
} elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"]) {
  $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"];
} elseif (getenv("HTTP_X_FORWARDED_FOR")) {
  $ip = getenv("HTTP_X_FORWARDED_FOR");
} elseif (getenv("HTTP_CLIENT_IP")) {
  $ip = getenv("HTTP_CLIENT_IP");
} elseif (getenv("REMOTE_ADDR")) {
  $ip = getenv("REMOTE_ADDR");
} else {
  $ip = "Unknown";
}
echo $ip;
?>

Method 3:

<?php
$iipp = $_SERVER["REMOTE_ADDR"];
echo $iipp;
?>

Method 4:

<?php
$user_IP = ($_SERVER["HTTP_VIA"]) ? $_SERVER["HTTP_X_FORWARDED_FOR"] : $_SERVER["REMOTE_ADDR"];
$user_IP = ($user_IP) ? $user_IP : $_SERVER["REMOTE_ADDR"];
echo $user_IP;
?>

Method 5:

<?php
function get_real_ip() {
  $ip = false;
  if (!empty($_SERVER["HTTP_CLIENT_IP"])) {
    $ip = $_SERVER["HTTP_CLIENT_IP"];
  }
  if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $ips = explode(", ", $_SERVER['HTTP_X_FORWARDED_FOR']);
    if ($ip) {
      array_unshift($ips, $ip);
      $ip = false;
    }
    for ($i = 0; $i < count($ips); $i++) {
      if (!eregi("^(10|172\.16|192\.168)\.", $ips[$i])) {
        $ip = $ips[$i];
        break;
      }
    }
  }
  return ($ip ? $ip : $_SERVER['REMOTE_ADDR']);
}
echo get_real_ip();
?&gt;

Method 6:

<?php
if (getenv('HTTP_CLIENT_IP')) {
  $onlineip = getenv('HTTP_CLIENT_IP');
} elseif (getenv('HTTP_X_FORWARDED_FOR')) {
  $onlineip = getenv('HTTP_X_FORWARDED_FOR');
} elseif (getenv('REMOTE_ADDR')) {
  $onlineip = getenv('REMOTE_ADDR');
} else {
  $onlineip = $HTTP_SERVER_VARS['REMOTE_ADDR'];
}
echo $onlineip;
?>

Each snippet can be used depending on the server environment and the presence of proxy or CDN headers, providing developers with flexible options to accurately determine the originating IP address of a request.