实战-端口扫描器

package main
import (
    "flag"
    "fmt"
    "github.com/gookit/color"
    "net"
    "os"
    "regexp"
    "strconv"
    "strings"
    "sync"
)
var (
    port           int    //端口
    portRange      string //端口范围
    parallelCounts int    //并行数
)
func init() {
    flag.IntVar(&port, "p", 80, "port")
    flag.StringVar(&portRange, "r", "", "range ports. eg. 1-65535")
    flag.IntVar(&parallelCounts, "n", 50, "parallel counts")
    //给默认用法输出，加点自定义的提示
    flag.Usage = func() {
        fmt.Println("Usege:portscan [options] <ip> \noptions:")
        flag.PrintDefaults()
    }
    flag.Parse()
}
func scanPort(ip net.IP, port int, wg *sync.WaitGroup, parallelChan *chan int) {
    defer wg.Done()
    tcpAddr := net.TCPAddr{
        IP:   ip,
        Port: port,
    }
    conn, err := net.DialTCP("tcp", nil, &tcpAddr)
    if err == nil {
        color.Green.Println("port " + strconv.Itoa(port) + " is opening")
        _ = conn.Close()
    }
    <-*parallelChan //通道不需要接收
}
func main() {
    args := flag.Args() //获取命令行参数
    if len(args) != 1 { //如果一个参数未输入
        flag.Usage() //打印用法
        os.Exit(1)   //退出
    }
    //解析IP格式是否为点分十进制，获取命令行第一个参数，注意这里是不包含flag绑定的那几个参数
    ip := net.ParseIP(flag.Arg(0))
    if ip == nil {
        fmt.Println("ip address is not a valid format，please check for this.")
        os.Exit(4)
    } else {
        wg := sync.WaitGroup{} // 用于协程任务控制
        if portRange == "" { //没指定端口范围的话，则扫描指定段端口
            wg.Add(1)
            parallelChan := make(chan int)
            go func() {
                parallelChan <- 1
            }()
            go scanPort(ip, port, &wg, &parallelChan)
            wg.Wait()
        } else { //如果-r参数传入了
            //从头匹配数字-数字的格式
            matched, _ := regexp.Match(`^\d+-\d+$`, []byte(portRange))
            if !matched {
                fmt.Println("the ports range is not a valid format,please check for this.")
                os.Exit(2)
            }
            ports := strings.Split(portRange, "-") //-符号分割
            startPort, err1 := strconv.Atoi(ports[0]) //字符串转int
            endPort, err2 := strconv.Atoi(ports[1])
            if err1 != nil || err2 != nil || startPort < 1 || endPort < 2 || endPort <= startPort || parallelCounts < 1 {
                flag.Usage()
                os.Exit(3)
            }
            wg.Add(endPort - startPort + 1)
            parallelChan := make(chan int, parallelCounts) // 用于控制协程数
            for i := startPort; i <= endPort; i++ {
                parallelChan <- 1
                go scanPort(ip, i, &wg, &parallelChan)
            }
            wg.Wait()
        }
    }
}

优化

输出加上时间戳，加入端口超范围判断。

package main
import (
    "flag"
    "fmt"
    "net"
    "os"
    "regexp"
    "strconv"
    "strings"
    "sync"
    "time"
    "github.com/gookit/color"
)
var (
    port           int    //端口
    portRange      string //端口范围
    parallelCounts int    //并行数
)
func init() {
    flag.IntVar(&port, "p", 80, "port")
    flag.StringVar(&portRange, "r", "", "range ports. eg. 1-65535")
    flag.IntVar(&parallelCounts, "n", 50, "parallel counts")
    //给默认用法输出，加点自定义的提示
    flag.Usage = func() {
        fmt.Println("Usege:portscan [options] <ip> \noptions:")
        flag.PrintDefaults()
    }
    flag.Parse()
}
func scanPort(ip net.IP, port int, wg *sync.WaitGroup, parallelChan *chan int) {
    defer wg.Done()
    tcpAddr := net.TCPAddr{
        IP:   ip,
        Port: port,
    }
    conn, err := net.DialTCP("tcp", nil, &tcpAddr)
    if err == nil {
        timeStr := time.Now().Format("2006-01-02 15:04:05") //获取时间戳，这是固定写法
        color.Cyan.Printf("[%s]", timeStr)
        color.Green.Println(" port " + strconv.Itoa(port) + " is opening")
        _ = conn.Close()
    }
    <-*parallelChan //通道不需要接收
}
func main() {
    args := flag.Args() //获取命令行参数
    if len(args) != 1 { //如果一个参数未输入
        flag.Usage() //打印用法
        os.Exit(1)   //退出
    }
    //解析IP格式是否为点分十进制，获取命令行第一个参数，注意这里是不包含flag绑定的那几个参数
    ip := net.ParseIP(flag.Arg(0))
    if ip == nil {
        color.Red.Println("ip address is not a valid format, please check for this.")
        os.Exit(4)
    } else {
        wg := sync.WaitGroup{} // 用于协程任务控制
        if portRange == "" { //没指定端口范围的话，则扫描-p参数，启用一个协程
            if port > 65535 {
                color.Red.Println("The port is too big, please check for this.")
                os.Exit(6)
            }
            wg.Add(1)
            parallelChan := make(chan int)
            go func() {
                parallelChan <- 1
            }()
            go scanPort(ip, port, &wg, &parallelChan)
            wg.Wait()
        } else { //如果-r参数传入了
            //从头匹配数字-数字的格式
            matched, _ := regexp.Match(`^\d+-\d+$`, []byte(portRange))
            if !matched {
                color.Red.Println("the ports range is not a valid format,please check for this.")
                os.Exit(2)
            }
            ports := strings.Split(portRange, "-") //-符号分割
            startPort, err1 := strconv.Atoi(ports[0]) //字符串转int
            endPort, err2 := strconv.Atoi(ports[1])
            if startPort > 65535 || endPort > 65535 {
                color.Red.Println("The port is too big, please check for this.")
                os.Exit(3)
            }
            if err1 != nil || err2 != nil || startPort < 1 || endPort < 2 || endPort <= startPort || parallelCounts < 1 {
                flag.Usage()
                os.Exit(5)
            }
            wg.Add(endPort - startPort + 1)
            parallelChan := make(chan int, parallelCounts) // 用于控制协程数
            for i := startPort; i <= endPort; i++ {
                parallelChan <- 1
                go scanPort(ip, i, &wg, &parallelChan)
            }
            wg.Wait()
        }
    }
}