IPv4 Private Address Ranges Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ipv4 private address ranges, ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// IPv4 Private Address Ranges
// ReDoS-safe | RegexVault — Web & Network > IPv4

package validation

import "regexp"

var ipv4PrivateAddressRangesRe = regexp.MustCompile(`^(?:10\.(?:(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.){2}(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])|172\.(?:1[6-9]|2[0-9]|3[01])\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])|192\.168\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))$`)

func ValidateIpv4PrivateAddressRanges(s string) bool {
    return ipv4PrivateAddressRangesRe.MatchString(s)
}

// Example
// fmt.Println(ValidateIpv4PrivateAddressRanges("10.0.0.1")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > IPv4 category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. 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

172.x range uses 1[6-9]|2[0-9]|3[01] to cover exactly 16–31. Three distinct top-level alternations for each private block — no shared suffix, which prevents backtracking.