Well-Known Port (1–1023) Regex for Go

What this pattern does

This page provides a well-structured, multi-part regular expression for matching well-known port (1–1023), 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

// Well-Known Port (1–1023)
// ReDoS-safe | RegexVault — Web & Network > Port

package validation

import "regexp"

var wellknownPort11023Re = regexp.MustCompile(`^(?:102[0-3]|10[01][0-9]|[1-9][0-9]{0,2})$`)

func ValidateWellknownPort11023(s string) bool {
    return wellknownPort11023Re.MatchString(s)
}

// Example
// fmt.Println(ValidateWellknownPort11023("1")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > Port 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

Common well-known ports: 21 (FTP), 22 (SSH), 25 (SMTP), 53 (DNS), 80 (HTTP), 443 (HTTPS). Full list maintained by IANA.