IPv6 Global Unicast Address (2000::/3) Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching ipv6 global unicast address (2000::/3), ported and verified for PHP. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// IPv6 Global Unicast Address (2000::/3)
// ReDoS-safe | RegexVault — Web & Network > IPv6

define('IPV6_GLOBAL_UNICAST_ADDRESS_20003_PATTERN', '/^[23][0-9a-fA-F]{3}(?::[0-9a-fA-F]{1,4}){7}$/');

function validate_ipv6_global_unicast_address_20003(string $input): bool {
    return (bool) preg_match(IPV6_GLOBAL_UNICAST_ADDRESS_20003_PATTERN, $input);
}

// Example
var_dump(validate_ipv6_global_unicast_address_20003("2001:0db8:85a3:0000:0000:8a2e:0370:7334")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > IPv6 category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Global unicast addresses are publicly routable. The 2000::/3 block is the current IANA global unicast allocation (covers 2000:: to 3fff::). Only matches fully expanded form — use net-ipv6-02 for compressed forms.