PHP: HowTo Read an IP Address of Remote Computer / Browser

Posted on in Categories , , last updated August 25, 2013

How do I read an IP address of remove system or browser using PHP server side programming language? How can I get client IP address and store it to the variable called $ip using php+apache?

PHP has in built facility to detect remote browser, IP address, and other properties. These values are assigned to special variable. In this case, it is assigned to a variable called REMOTE_ADDR. You can use any one of the following statement to obtained or read IP address.

PHP syntax to find out an IP address

The syntax is:

$ip = $_SERVER['REMOTE_ADDR'];

OR

$ip= $REMOTE_ADDR;

OR

$ip = $_SERVER['REMOTE_ADDR'];

OR

$ip = getenv('HTTP_CLIENT_IP');

PHP syntax to find out remote host name

The syntax is:

$ip = $_SERVER['REMOTE_ADDR'];
$hostname = gethostbyaddr($ip);

OR

$hostname = gethostbyaddr($_SERVER['REMOTE_ADDR']);

Example

Create a file called client-ip.php and store or upload at your Web-server DocumentRoot (e.g. /var/www/html/client-ip.php):

<?php
// client-ip.php : Demo script by nixCraft <www.cyberciti.biz>
// get an IP address
$ip = $_SERVER['REMOTE_ADDR'];
// display it back
echo "<h2>Client IP Demo</h2>";
echo "Your IP address : " . $ip;
echo "<br>Your hostname : ". gethostbyaddr($ip) ;
?>

Save and close the file. Open a web-browser and type your url:
http://your-sercer-name-here/client-ip.php
OR
http://127.0.0.1/client-ip.php
Sample outputs:

Fig.01 client-ip.php output
Fig.01 client-ip.php output

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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29 comment

  2. echo “ Your hostname : ” . GetHostByName($ip);

    You can get the host name from IP.gethostbyname

    gethostbyname – Get the IP address corresponding to a given Internet host name

    Try the gethostbyaddr for this task.

    Reply Report comment

  6. I don’t understand something. 5 of my friends using different HOSTS in different CITIES used a script that logged each user’s IP address and time in a database and all their IP was exactly the same as mine. I used $_SERVER[‘REMOTE_ADDR’]

    Reply Report comment

    1. Hey ben, all of your IP’s are the same since all of you are using the same ISP or the same main ISP:

      user1->ISP1->main_isp->internet
      you->ISP3->main_isp->internet

      So the website actually detects your main_isp IP address since none of you have a dedicated IP address on the internet.

      Reply Report comment

  7. They are all behind the same proxy-server. In that case $_SERVER[‘REMOTE_ADDR’] provides you with the ip-address of the proxy-server.

    This function will determine the real ip-adress:

    function ipCheck() {
		if (getenv('HTTP_CLIENT_IP')) {
			$ip = getenv('HTTP_CLIENT_IP');
		}
		elseif (getenv('HTTP_X_FORWARDED_FOR')) {
			$ip = getenv('HTTP_X_FORWARDED_FOR');
		}
		elseif (getenv('HTTP_X_FORWARDED')) {
			$ip = getenv('HTTP_X_FORWARDED');
		}
		elseif (getenv('HTTP_FORWARDED_FOR')) {
			$ip = getenv('HTTP_FORWARDED_FOR');
		}
		elseif (getenv('HTTP_FORWARDED')) {
			$ip = getenv('HTTP_FORWARDED');
		}
		else {
			$ip = $_SERVER['REMOTE_ADDR'];
		}
		return $ip;
	}
    Reply Report comment

    1. it do not work if client computer is using ISA Server.

      but code is working fine if client is connected with DSL , or modem direct internet connection.

      can any one provide how do I resolved issue on intranet application/ Client is using ISA

      Reply Report comment

  10. supose am chatting with my friend using gtalk how would i get his ip address. [what command do i got to use in DOS]. what i got his ip what command [DOS} do i use to get his host name.
    One more thing to what command to view that a specified computer is online or not.

    Reply Report comment

  12. Why do you have 2 x same conditions in this script ?

    elseif (getenv(‘HTTP_X_FORWARDED_FOR’)) {
    $ip = getenv(‘HTTP_X_FORWARDED_FOR’); x 2
    }
    and

    elseif (getenv(‘HTTP_FORWARDED’)) {
    $ip = getenv(‘HTTP_FORWARDED’); x 2
    }

    Reply Report comment

  15. Simple working excellent

    <?php
$ip = $_SERVER['REMOTE_ADDR'];
$hostaddress = gethostbyaddr($ip);
$browser = $_SERVER['HTTP_USER_AGENT'];
$referred = $_SERVER['HTTP_REFERER']; // a quirky spelling mistake that stuck in php

print "Display IP address:";
print "$ip";
print "More detailed host address:";
print "$hostaddress";
print "Display browser info:";
print "$browser";
print "Where you came from (if you clicked on a link to get here:";
if ($referred == "") {
print "Page was directly requested";
}
else {
print "$referred";
}
?>
    Reply Report comment

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