Port scanner in Go

portscan.go

package main

import (
	"fmt"
	"net"
	"sync"
	"time"
)

func dial_port(host string, port int, wg *sync.WaitGroup) {
	// Dial the port with a one second deadline
	addr := fmt.Sprintf("%s:%d", host, port)

	conn, err := net.DialTimeout("tcp", addr, time.Second)
	if err != nil {
		fmt.Printf("%-5d FAIL\t%s\n", port, err)
	} else {
		fmt.Printf("%-5d OK\n", port)
		conn.Close()
	}

	// Notify the waitgroup that we are done.
	wg.Done()
}

func main() {
	host := "scanme.nmap.org"
	ports := []int{22, 80, 8080, 443}

	// Use a waitgroup to synchronize the coroutines
	var wg sync.WaitGroup

	// Dial all the ports
	fmt.Printf("%s\n", host)
	for i := 0; i < len(ports); i++ {
		wg.Add(1)
		go dial_port(host, ports[i], &wg)
	}

	// Wait for all coroutines to finish
	wg.Wait()
}