IPv6 in URL Bracket Notation Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching ipv6 in url bracket notation, 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 in URL Bracket Notation
// ReDoS-safe | RegexVault — Web & Network > IPv6

define('IPV6_IN_URL_BRACKET_NOTATION_PATTERN', '/^\[(?:[0-9a-fA-F]{0,4}:){2,7}[0-9a-fA-F]{0,4}\]$/');

function validate_ipv6_in_url_bracket_notation(string $input): bool {
    return (bool) preg_match(IPV6_IN_URL_BRACKET_NOTATION_PATTERN, $input);
}

// Example
var_dump(validate_ipv6_in_url_bracket_notation("[2001:db8::1]")); // 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

IPv6 addresses in URLs must be in square brackets per RFC 2732. This pattern uses a simplified compressed IPv6 match — it accepts the major forms but may allow some technically invalid compressed sequences. For strict validation, pair with full IPv6 validation (net-ipv6-02) after stripping the brackets.