Valid TCP/UDP Port (1–65535) Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching valid tcp/udp port (1–65535), 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

// Valid TCP/UDP Port (1–65535)
// ReDoS-safe | RegexVault — Web & Network > Port

package validation

import "regexp"

var validTcpudpPort165535Re = regexp.MustCompile(`^(?:6553[0-5]|655[0-2][0-9]|65[0-4][0-9]{2}|6[0-4][0-9]{3}|[1-5][0-9]{4}|[1-9][0-9]{0,3})$`)

func ValidateValidTcpudpPort165535(s string) bool {
    return validTcpudpPort165535Re.MatchString(s)
}

// Example
// fmt.Println(ValidateValidTcpudpPort165535("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

Port 0 is excluded — it is a wildcard/reserved port, not a valid destination. The alternation order ensures strict 1–65535 matching without ambiguity.