PHP inet_pton Function

last modified April 4, 2025

The PHP inet_pton function converts human-readable IP addresses to packed binary strings. It's essential for network programming and storage.

Basic Definition

inet_pton converts IPv4 and IPv6 addresses from text to binary. It stands for "internet presentation to network" format conversion.

Syntax: inet_pton(string $ip): string|false. Returns binary string on success, false on invalid input. Works with both IP versions.

Convert IPv4 Address

This example demonstrates converting a standard IPv4 address to binary.

ipv4_conversion.php

<?php

declare(strict_types=1);

$ip = "192.168.1.1";
$binary = inet_pton($ip);

if ($binary !== false) {
    echo "Binary representation: " . bin2hex($binary);
} else {
    echo "Invalid IP address";
}

The function converts "192.168.1.1" to a 4-byte binary string. We use bin2hex to display the binary in readable hexadecimal format.

Convert IPv6 Address

This shows how to convert an IPv6 address to its binary representation.

ipv6_conversion.php

<?php

declare(strict_types=1);

$ip = "2001:0db8:85a3:0000:0000:8a2e:0370:7334";
$binary = inet_pton($ip);

if ($binary !== false) {
    echo "Binary representation: " . bin2hex($binary);
} else {
    echo "Invalid IP address";
}

IPv6 addresses convert to 16-byte binary strings. The example shows a valid IPv6 address in compressed format being converted.

Validate IP Address

This example uses inet_pton to validate both IPv4 and IPv6.

ip_validation.php

<?php

declare(strict_types=1);

function isValidIP($ip) {
    return inet_pton($ip) !== false;
}

$testIPs = ["192.168.1.1", "256.0.0.1", "2001:db8::1", "invalid"];

foreach ($testIPs as $ip) {
    $valid = isValidIP($ip) ? "valid" : "invalid";
    echo "$ip is $valid\n";
}

The function checks if inet_pton returns non-false. This validates both IP versions without needing separate checks.

Compare IP Addresses

This demonstrates comparing IP addresses after converting to binary.

ip_comparison.php

<?php

declare(strict_types=1);

$ip1 = "192.168.001.001";
$ip2 = "192.168.1.1";

$bin1 = inet_pton($ip1);
$bin2 = inet_pton($ip2);

if ($bin1 && $bin2) {
    echo $bin1 === $bin2 ? "Same IP" : "Different IPs";
} else {
    echo "Invalid IP(s) provided";
}

Binary comparison handles different textual representations of the same IP. Leading zeros and formatting differences don't affect the comparison.

Store IP in Database

This example shows storing IP addresses efficiently in binary format.

ip_storage.php

<?php

declare(strict_types=1);

$ip = "203.0.113.45";
$binaryIP = inet_pton($ip);

if ($binaryIP !== false) {
    // Store in database as BINARY(16) for both IPv4 and IPv6
    $pdo = new PDO("mysql:host=localhost;dbname=test", "user", "pass");
    $stmt = $pdo->prepare("INSERT INTO logs (ip) VALUES (?)");
    $stmt->execute([$binaryIP]);
    echo "IP stored successfully";
}

Storing IPs in binary format saves space and allows for efficient comparison. The same column can store both IPv4 and IPv6 addresses.

Best Practices

Validation: Always check for false return value
Storage: Use binary columns for IP storage in databases
Comparison: Compare binary representations for accuracy
Display: Use inet_ntop to convert back for display

Source

PHP inet_pton Documentation

This tutorial covered the PHP inet_pton function with practical examples for IP address conversion, validation, and storage.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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