Simple network port scanning method implemented in Go language

This article illustrates a simple network port scanning method implemented by Go. Share with you for your reference. The specific implementation method is as follows:

package main

import (

 "net"

 "fmt"

 "os"

 "runtime"

 "time"

 "strconv"

)
func loop(startport, endport int, inport chan int) {

  for i := startport; i <= endport; i++{

   inport <- i

  }

}
func scanner(inport, outport, out chan int, ip net.IP, endport int){

 for{

  in := <- inport

  //fmt.Println(in)

  tcpaddr := &net.TCPAddr{ip,in}

  conn, err := net.DialTCP("tcp", nil, tcpaddr)

  if err != nil {

   outport <- 0

  }else{

   outport <- in 

  }

  conn.Close()

  if in == endport{

   out <- in

  }

 }

}
func main() {

 starttime := time.Now().Unix()

 runtime.GOMAXPROCS(4)

 inport := make(chan int)

 outport := make(chan int)

 out := make(chan int)

 collect := []int{}

 if len(os.Args) != 4 {

  fmt.Println("Usage: scanner.exe IP startport endport")

  fmt.Println("Endport must be larger than startport")

  os.Exit(0)

 }

 ip := net.ParseIP(os.Args[1])

 if(os.Args[3] < os.Args[2]) {

  fmt.Println("Usage: scanner IP startport endport")

  fmt.Println("Endport must be larger than startport")

  os.Exit(0)

 }

 startport, _:= strconv.Atoi(os.Args[2])

 endport, _ := strconv.Atoi(os.Args[3])

 go loop(startport, endport, inport)

 for{

  select {

   case <-out:

    fmt.Println(collect)

    endtime := time.Now().Unix()

    fmt.Println("The scan process has spent ",endtime-starttime,"second")

    os.Exit(0)

   default:

    go scanner(inport, outport, out, ip, endport)

    port := <- outport

    

    if port != 0{

     collect = append(collect, port)

    }

  }  

 }

}

I hope this article has been helpful to your programming of Go language.