Get IP Address in PHP

To learn ‘Get IP Address in PHP’, first, we will study the IP Address. An IP address or an Internet Protocol address is an address that is a numerical address or label that every system or device connected to a network has. The IP address is assigned to every such device. These devices use internet protocol for any type of communication.

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IP Version

Below points Explain IP version:

• An IP version is defined according to the bit of the internet protocol label. For example, IPv4, which is an earlier version defines a 32-bit number internet protocol address. With the growth of the internet, IPv6 came into being which defines a 128-bit number IP label. IPv6 is being used since 1995 till today. Internet Protocol address is written in the human-understandable language. An example of IPv4 is as follows, 170.17.260.2 and an example for IPv6 is 2001:db8:2:1434:1:587:5:2.
• The space acquired by internet protocol addresses is globally managed. A registry called Internet Assigned Numbers Authority along with the other five regional registries makes the space management for internet protocol addresses possible. The IANA is responsible for allocating and managing spaces of internet protocol addresses to all the end-users and other internet providers in their designated areas or territories. Similarly, all the devices connected to an internet service provider network is assigned a unique internet protocol address.
• There are static internet protocol addresses that do not change often, they are provided to the servers. The internet service providers provide a specific and unique internet protocol address to a machine that is using a modem. That IP address is unique for a session and might change for the next session.

Identifying and Returning IP Address in PHP

For security reasons, the sites collect the IP addresses of the visitors of their sites. There is an easy way to get this address in PHP. There is a specific array in PHP that helps and returns the IP address of your machine. An array is known as ‘$_SERVER’. It contains information about the paths, headers and script locations. The web server creates the information required for $_SERVER array. Sometimes this the server does not create or provide all the information required by the array, they might omit some of it. Thus there is another array that can be used in such cases. It is written as, ‘SERVER_ADDR’. This array returns the IP address of the server under which script is running.

Methods Use to Get IP Address in PHP

Below is the example used to get an IP address in php:

Examples #1

The simplest way is to use $_SERVER with ‘REMOTE_ADDR’, it will return the user’s IP address who is currently viewing the page.

• Example using [‘REMOTE_ADDR’] to identify the server’s IP address in PHP.

Code:

<?php
echo 'User IP - '.$_SERVER['REMOTE_ADDR'];
?>

Output:

Example #2

Another method, called ‘SERVER_ADDR’, which is also used to retrieve the IP address of the server. 

• Example using [‘SERVER_ADDR’] to identify the server’s IP address in PHP.

Code:

<?php
// PHP program to retrieve server’s Internet Protocol address
// Creating a variable to store the server address
$ip_server = $_SERVER['SERVER_ADDR'];
// Displaying the retrieved address
echo "Server IP Address is: $ip_server";
?>

Output:

Explanation to the above program: The above example array [$_SERVER] is helpful is the machine is not attached via proxy. If the machine is connected to the internet through or via the proxy server, $_SERVER[‘REMOTE_ADDR’] in PHP does not return the correct IP address. It just returns the IP address of the proxy server and of the user’s or client’s machine. In this situation, another method is used to retrieve the correct address.

Example #3

The following example is used to return the correct and real IP address even if the machine is hiding behind a proxy server. It uses an extra pair of SERVER variables that are available to get the exact IP address of the client’s system or machine. They are known as HTTP_CLIENT_IP and HTTP_X_FORWARDED_FOR.

• Example using [‘HTTP_CLIENT_IP’] and [‘HTTP_X_FORWARDED_FOR’] to identify the server’s IP address in PHP.

Code:

<?php
function RetrieveUserIP()
{
if(!empty($_SERVER['HTTP_CLIENT_IP']))
{
$address=$_SERVER['HTTP_CLIENT_IP'];
}
elseif(!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
{
$address=$_SERVER['HTTP_X_FORWARDED_FOR'];
}
else
{
$address=$_SERVER['REMOTE_ADDR'];
}
return $address;
}
echo 'User IP Address is'.RetrieveUserIP();
?>

Output:

If one is to understand the flow of actions of the above code, one can refer to the following flow chart for the same.

Explanation to the above program: The above example to retrieve the IP address uses two variables, [‘HTTP_CLIENT_IP’] and [‘HTTP_X_FORWARDED_FOR’]. In the program, we make our first attempt to directly get it off the machine using HTTP_CLIENT_IP. If that is not available, we try for ‘forwarded for’ IP using HTTP_X_FORWARDD_FOR. When both conditions fall null, we try getting the IP address using the REMOTE_ADDR variable.

Points to be Remember

Below the points should be remembered to Getting an IP address in php:

1. That when we ran the above code, the returned IP address is displayed as::1. This is known as a loopback address which actually is represented as 127 times zeroes followed by a 1 that is (0000…. 127 times….1). If we are to write it down, it will be written as:

2. But in IPv6, we can represent this big label in a short form. So if there are all zeroes in a single block, it can be replaced with a single zero. So when followed the above rule, it becomes: 0:0:0:0:0:0:0:0001;

3. Again, the zeroes can be eliminated and we are left with:: 0001

4. Which again gets reduced to ‘:: 1’, thus the output.

Explanation to the above code: If they are made to run, they might not give any output or might return a run time error since private domains do not provide their internet protocol addresses. Whilst if the above codes are executed on a local server or a local host, like we have used a WAMP server, it will provide an output according to the IP version, that is, if it is an IPv4, the Internet protocol address will be displayed as ‘127:0:0:1’ while if it is an IPv6, the internet protocol address will be displayed as above, that it, ‘:: 1’

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