How to get client IP address in PHP

Are you using $_SERVER[‘REMOTE_ADDR’] to find the the client’s IP address in PHP? Well dude, you might be amazed to know that it may not return the true IP address of the client at all time. If your client is connected to the Internet through Proxy Server then $_SERVER[‘REMOTE_ADDR’] in PHP just returns the the IP address of the proxy server not of the client’s machine. So here is a simple function in PHP to find the real IP address of the client’s machine. There are extra Server variable which might be available to determine the exact IP address of the client’s machine in PHP, they are HTTP_CLIENT_IP and HTTP_X_FORWARDED_FOR.

Function to find real IP address in PHP

function getRealIpAddr()
{
    if (!empty($_SERVER['HTTP_CLIENT_IP']))   //check ip from share internet
    {
      $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))   //to check ip is pass from proxy
    {
      $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
      $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

In this PHP function, first attempt is to get the direct IP address of client’s machine, if not available then try for forwarded for IP address using HTTP_X_FORWARDED_FOR. And if this is also not available, then finally get the IP address using REMOTE_ADDR.

Commenfs from StackOverflow

Whatever you do, make sure not to trust data sent from the client. $_SERVER['REMOTE_ADDR']contains the real IP address of the connecting party. That is the most reliable value you can find.

However, they can be behind a proxy server in which case the proxy may have set the $_SERVER['HTTP_X_FORWARDED_FOR'], but this value is easily spoofed. For example, it can be set by someone without a proxy, or the IP can be an internal IP from the LAN behind the proxy.

This means that if you are going to save the $_SERVER['HTTP_X_FORWARDED_FOR'], make sure youalso save the $_SERVER['REMOTE_ADDR'] value. E.g. by saving both values in different fields in your database.

If you are going to save the IP to a database as a string, make sure you have space for at least 45 characters. IPv6 is here to stay and those addresses are larger than the older IPv4 addresses.

(Note that IPv6 usually uses 39 characters at most but there is also a special IPv6 notation for IPv4 addresses which in its full form can be up to 45 characters. So if you know what you are doing you can use 39 characters, but if you just want to set and forget it, use 45).

Another way to get IP from Zend

My favourite solution is the way Zend Framework 2 uses. It also considers the $_SERVER propertiesHTTP_X_FORWARDED_FOR, HTTP_CLIENT_IP, REMOTE_ADDR but it declares a class for it to set some trusted proxies and it returns one IP address not an array. I think this is the solution that comes closest to it:

class RemoteAddress
{
    /**
     * Whether to use proxy addresses or not.
     *
     * As default this setting is disabled - IP address is mostly needed to increase
     * security. HTTP_* are not reliable since can easily be spoofed. It can be enabled
     * just for more flexibility, but if user uses proxy to connect to trusted services
     * it's his/her own risk, only reliable field for IP address is $_SERVER['REMOTE_ADDR'].
     *
     * @var bool
     */
    protected $useProxy = false;

    /**
     * List of trusted proxy IP addresses
     *
     * @var array
     */
    protected $trustedProxies = array();

    /**
     * HTTP header to introspect for proxies
     *
     * @var string
     */
    protected $proxyHeader = 'HTTP_X_FORWARDED_FOR';

    // [...]

    /**
     * Returns client IP address.
     *
     * @return string IP address.
     */
    public function getIpAddress()
    {
        $ip = $this->getIpAddressFromProxy();
        if ($ip) {
            return $ip;
        }

        // direct IP address
        if (isset($_SERVER['REMOTE_ADDR'])) {
            return $_SERVER['REMOTE_ADDR'];
        }

        return '';
    }

    /**
     * Attempt to get the IP address for a proxied client
     *
     * @see http://tools.ietf.org/html/draft-ietf-appsawg-http-forwarded-10#section-5.2
     * @return false|string
     */
    protected function getIpAddressFromProxy()
    {
        if (!$this->useProxy
            || (isset($_SERVER['REMOTE_ADDR']) && !in_array($_SERVER['REMOTE_ADDR'], $this->trustedProxies))
        ) {
            return false;
        }

        $header = $this->proxyHeader;
        if (!isset($_SERVER[$header]) || empty($_SERVER[$header])) {
            return false;
        }

        // Extract IPs
        $ips = explode(',', $_SERVER[$header]);
        // trim, so we can compare against trusted proxies properly
        $ips = array_map('trim', $ips);
        // remove trusted proxy IPs
        $ips = array_diff($ips, $this->trustedProxies);

        // Any left?
        if (empty($ips)) {
            return false;
        }

        // Since we've removed any known, trusted proxy servers, the right-most
        // address represents the first IP we do not know about -- i.e., we do
        // not know if it is a proxy server, or a client. As such, we treat it
        // as the originating IP.
        // @see http://en.wikipedia.org/wiki/X-Forwarded-For
        $ip = array_pop($ips);
        return $ip;
    }

    // [...]
}

Advanced method to retrieve the client IP in PHP with validattion

This is the most advanced method I have found, already tried some others in the past. Valid to ensure to get the IP address of visitor (but please note that any hacker could falsify ip address easily).

function get_ip_address() {
    // check for shared internet/ISP IP
    if (!empty($_SERVER['HTTP_CLIENT_IP']) && validate_ip($_SERVER['HTTP_CLIENT_IP'])) {
        return $_SERVER['HTTP_CLIENT_IP'];
    }

    // check for IPs passing through proxies
    if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        // check if multiple ips exist in var
        if (strpos($_SERVER['HTTP_X_FORWARDED_FOR'], ',') !== false) {
            $iplist = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
            foreach ($iplist as $ip) {
                if (validate_ip($ip))
                    return $ip;
            }
        } else {
            if (validate_ip($_SERVER['HTTP_X_FORWARDED_FOR']))
                return $_SERVER['HTTP_X_FORWARDED_FOR'];
        }
    }
    if (!empty($_SERVER['HTTP_X_FORWARDED']) && validate_ip($_SERVER['HTTP_X_FORWARDED']))
        return $_SERVER['HTTP_X_FORWARDED'];
    if (!empty($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']) && validate_ip($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']))
        return $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'];
    if (!empty($_SERVER['HTTP_FORWARDED_FOR']) && validate_ip($_SERVER['HTTP_FORWARDED_FOR']))
        return $_SERVER['HTTP_FORWARDED_FOR'];
    if (!empty($_SERVER['HTTP_FORWARDED']) && validate_ip($_SERVER['HTTP_FORWARDED']))
        return $_SERVER['HTTP_FORWARDED'];

    // return unreliable ip since all else failed
    return $_SERVER['REMOTE_ADDR'];
}

/**
 * Ensures an ip address is both a valid IP and does not fall within
 * a private network range.
 */
function validate_ip($ip) {
    if (strtolower($ip) === 'unknown')
        return false;

    // generate ipv4 network address
    $ip = ip2long($ip);

    // if the ip is set and not equivalent to 255.255.255.255
    if ($ip !== false && $ip !== -1) {
        // make sure to get unsigned long representation of ip
        // due to discrepancies between 32 and 64 bit OSes and
        // signed numbers (ints default to signed in PHP)
        $ip = sprintf('%u', $ip);
        // do private network range checking
        if ($ip >= 0 && $ip <= 50331647) return false;
        if ($ip >= 167772160 && $ip <= 184549375) return false;
        if ($ip >= 2130706432 && $ip <= 2147483647) return false;
        if ($ip >= 2851995648 && $ip <= 2852061183) return false;
        if ($ip >= 2886729728 && $ip <= 2887778303) return false;
        if ($ip >= 3221225984 && $ip <= 3221226239) return false;
        if ($ip >= 3232235520 && $ip <= 3232301055) return false;
        if ($ip >= 4294967040) return false;
    }
    return true;
}

Simple way to determine client IP in PHP

Here is a cleaner code sample of a good way to get the ip of the user.

$ip = $_SERVER['REMOTE_ADDR']?:($_SERVER['HTTP_X_FORWARDED_FOR']?:$_SERVER['HTTP_CLIENT_IP']);