sl_get_ip

ip.php

function sl_get_ip() {
  if ( isset( $_SERVER['HTTP_CLIENT_IP'] ) && ! empty( $_SERVER['HTTP_CLIENT_IP'] ) ) {
    $ip = $_SERVER['HTTP_CLIENT_IP'];
  } elseif ( isset( $_SERVER['HTTP_X_FORWARDED_FOR'] ) && ! empty( $_SERVER['HTTP_X_FORWARDED_FOR'] ) ) {
    $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
  } else {
    $ip = ( isset( $_SERVER['REMOTE_ADDR'] ) ) ? $_SERVER['REMOTE_ADDR'] : '0.0.0.0';
  }
	$ip = filter_var( $ip, FILTER_VALIDATE_IP );
  $ip = ( $ip === false ) ? '0.0.0.0' : $ip;
  
  return $ip;
}

echo sl_get_ip();