How to Get the Client IP Address in PHP

Frequently, it is necessary to gather clients’ IP addresses for tracking activity or security purposes.

Using the $_SERVER Variable

The <kbd class="highlighted">$_SERVER</kbd> variable provides a simple and efficient way to retrieve a user's IP address. It is an array that contains server and environment-related information in PHP.

Let’s begin with the simplest approach: accessing <kbd class="highlighted">$_SERVER['REMOTE_ADDR']</kbd>. It returns the IP address of the connecting user:

Retrieve Client IP via REMOTE_ADDR

<?php

echo 'User IP - ' . $_SERVER['REMOTE_ADDR'];

?>

However, $_SERVER['REMOTE_ADDR'] may return an incorrect address if the user is behind a proxy or load balancer. To handle this, you can check additional headers and validate the result:

Handle Proxies and Load Balancers

<?php

function getUserIpAddr()
{
  if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    // IP passed through proxy (may contain multiple IPs)
    $ip = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR'])[0];
  } elseif (!empty($_SERVER['HTTP_CLIENT_IP'])) {
    // IP from shared internet
    $ip = $_SERVER['HTTP_CLIENT_IP'];
  } else {
    $ip = $_SERVER['REMOTE_ADDR'];
  }
  return filter_var($ip, FILTER_VALIDATE_IP) ? $ip : 'Unknown';
}

echo 'User Real IP - ' . getUserIpAddr();

?>

Note: HTTP_X_FORWARDED_FOR and HTTP_CLIENT_IP headers can be spoofed. In production, always validate these against a trusted proxy list or use a dedicated library.

Getting IP Addresses of the Website

You can also resolve the IP address of any domain using the <kbd class="highlighted">gethostbyname()</kbd> function:

Resolve Domain to IP Address

<?php

 $ip_address = gethostbyname("www.google.com");
 echo "IP Address of Google is - " . $ip_address;
 echo "<br>";
 $ip_address = gethostbyname("www.javatpoint.com");
 echo "IP Address of javaTpoint is - " . $ip_address;

?>

Note: This function resolves DNS records, so the returned IP may differ from the actual server IP if the site uses a CDN or load balancer. Additionally, gethostbyname() is deprecated as of PHP 8.2; consider using dns_get_record() for modern compatibility.