Go黑帽子|TCP扫描器和代理

TCP扫描器

在worker函数中通过net.Dial测试端口连通，并把worker放到go routine中运行，port作为管道在主程序和携程中传递扫描信息

package main

import (
	"fmt"
	"net"
	"sort"
)

func worker(ports chan int, results chan int) {
	for p := range ports {
		address := fmt.Sprintf("127.0.0.1: %d", p)
		conn, err := net.Dial("tcp", address)
		if err != nil {
			results <- 0
			continue
		}
		conn.Close()
		results <- p
	}
}

func main() {
	ports := make(chan int, 100)
	results := make(chan int)
	var openports []int

	for i := 0; i < cap(ports); i++ {
		go worker(ports, results)
	}

	go func() {
		for i := 1; i <= 1024; i++ {
			ports <- i
		}
	}()

	for i := 0; i < 1024; i++ {
		port := <-results
		if port != 0 {
			openports = append(openports, port)
		}
	}

	close(ports)
	close(results)
	sort.Ints(openports)
	for _, port := range openports {
		fmt.Printf("%d open\n", port)
	}
}

TCP代理

建立监听接收来自客户端的消息，通过net.Dial连接目标服务器，并将客户端的消息通过io.Copy复制到目标服务器

package main

import (
	"fmt"
	"io"
	"log"
	"net"
)

func handle(src net.Conn) {
	dst, err := net.Dial("tcp", "192.168.1.52: 8089")
	if err != nil {
		log.Fatal("Unable to connect")
	}
	defer dst.Close()

	go func() {
		if _, err := io.Copy(dst, src); err != nil {
			log.Fatal(err)
		}
	}()

	if _, err := io.Copy(src, dst); err != nil {
		log.Fatal(err)
	}
}

func main() {
	fmt.Println("Waiting for connect")
	listener, err := net.Listen("tcp", ":8080")
	if err != nil {
		log.Fatal(err)
	}

	for {
		conn, err := listener.Accept()
		if err != nil {
			log.Fatal("Unable to accept connection")
		}
		fmt.Println("Accept connection")
		go handle(conn)
	}
}