GoLand编写 TCP 端口扫描器的详细过程

Go 语言编写 TCP 扫描器

TCP

• TCP，也就是传输控制协议（Transmission Control Protocol）。

TCP握手

• 建立 TCP连接（或者叫打开端口），需要3次握手

客户端 -> 端口打开 ->服务器

• syn （请求建立新连接）
• syn-ack （同意创建新连接）
• ack （表示响应）

• 服务端端口关闭 Closed Port
  • client -syn-> Server
  • Server -rst-> Client
• 如果存在防火墙 Filtered Port
  • Client —syn (Timeout)— Firewall Server

非并发的 TCP 扫描器

创建目录并在该目录创建main.go 文件

~/Code/go via 🐹 v1.20.3 via 🅒 base
➜ mcd tcp-scanner
Code/go/tcp-scanner via 🐹 v1.20.3 via 🅒 base
➜ go mod init
go: cannot determine module path for source directory /Users/qiaopengjun/Code/go/tcp-scanner (outside GOPATH, module path must be specified)
Example usage:
	'go mod init example.com/m' to initialize a v0 or v1 module
	'go mod init example.com/m/v2' to initialize a v2 module
Run 'go help mod init' for more information.
Code/go/tcp-scanner via 🐹 v1.20.3 via 🅒 base
➜ go mod init tcp-scanner
go: creating new go.mod: module tcp-scanner
Code/go/tcp-scanner via 🐹 v1.20.3 via 🅒 base
➜ c
Code/go/tcp-scanner via 🐹 v1.20.3 via 🅒 base
➜

main.go 文件

package main
import (
	"fmt"
	"net"
)
func main() {
	for i := 21; i < 120; i++ {
		address := fmt.Sprintf("20.194.168.28:%d", i)
		conn, err := net.Dial("tcp", address)
		if err != nil {
			fmt.Printf("%s failed 关闭了\n", address)
			continue
		}
		conn.Close()
		fmt.Printf("%s connected 打开了！！！\n", address)
	}
}

并发的 TCP 扫描器

package main
import (
	"fmt"
	"net"
	"sync"
	"time"
)
func main() {
	start := time.Now()
	var wg sync.WaitGroup
	for i := 21; i < 120; i++ {
		wg.Add(1)
		go func(j int) {
			defer wg.Done()
			address := fmt.Sprintf("20.194.168.28:%d", j)
			conn, err := net.Dial("tcp", address)
			if err != nil {
				fmt.Printf("%s 关闭了\n", address)
				return
			}
			conn.Close()
			fmt.Printf("%s 打开了！！！\n", address)
		}(i)
	}
	wg.Wait()
	elapsed := time.Since(start) / 1e9
	fmt.Printf("\n\n%d seconds", elapsed)
}
// func main() {
// 	for i := 21; i < 120; i++ {
// 		address := fmt.Sprintf("20.194.168.28:%d", i)
// 		conn, err := net.Dial("tcp", address)
// 		if err != nil {
// 			fmt.Printf("%s failed 关闭了\n", address)
// 			continue
// 		}
// 		conn.Close()
// 		fmt.Printf("%s connected 打开了！！！\n", address)
// 	}
// }

并发的 TCP 扫描器 - WORKER 池

package main
import (
	"fmt"
	"sync"
)
func worker(ports chan int, wg *sync.WaitGroup) {
	for p := range ports {
		fmt.Println("p", p)
		wg.Done()
	}
}
func main() {
	ports := make(chan int, 100)
	var wg sync.WaitGroup
	for i := 0; i < cap(ports); i++ {
		go worker(ports, &wg)
	}
	for i := 1; i < 1024; i++ {
		wg.Add(1)
		ports <- i
	}
	wg.Wait()
	close(ports)
}
// func main() {
// 	start := time.Now()
// 	var wg sync.WaitGroup
// 	for i := 21; i < 120; i++ {
// 		wg.Add(1)
// 		go func(j int) {
// 			defer wg.Done()
// 			address := fmt.Sprintf("20.194.168.28:%d", j)
// 			conn, err := net.Dial("tcp", address)
// 			if err != nil {
// 				fmt.Printf("%s 关闭了\n", address)
// 				return
// 			}
// 			conn.Close()
// 			fmt.Printf("%s 打开了！！！\n", address)
// 		}(i)
// 	}
// 	wg.Wait()
// 	elapsed := time.Since(start) / 1e9
// 	fmt.Printf("\n\n%d seconds", elapsed)
// }
// func main() {
// 	for i := 21; i < 120; i++ {
// 		address := fmt.Sprintf("20.194.168.28:%d", i)
// 		conn, err := net.Dial("tcp", address)
// 		if err != nil {
// 			fmt.Printf("%s failed 关闭了\n", address)
// 			continue
// 		}
// 		conn.Close()
// 		fmt.Printf("%s connected 打开了！！！\n", address)
// 	}
// }

优化之后

package main
import (
	"fmt"
	"net"
	"sort"
)
func worker(ports chan int, results chan int) {
	for p := range ports {
		address := fmt.Sprintf("20.194.168.28:%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
	var closeports []int
	for i := 0; i < cap(ports); i++ {
		go worker(ports, results)
	}
	go func() {
		for i := 1; i < 1024; i++ {
			ports <- i
		}
	}()
	for i := 1; i < 1024; i++ {
		port := <-results
		if port != 0 {
			openports = append(openports, port)
		} else {
			closeports = append(closeports, port)
		}
	}
	close(ports)
	close(results)
	sort.Ints(openports)
	sort.Ints(closeports)
	for _, port := range closeports {
		fmt.Printf("%d closed\n", port)
	}
	for _, port := range openports {
		fmt.Printf("%d opened\n", port)
	}
}
// func main() {
// 	start := time.Now()
// 	var wg sync.WaitGroup
// 	for i := 21; i < 120; i++ {
// 		wg.Add(1)
// 		go func(j int) {
// 			defer wg.Done()
// 			address := fmt.Sprintf("20.194.168.28:%d", j)
// 			conn, err := net.Dial("tcp", address)
// 			if err != nil {
// 				fmt.Printf("%s 关闭了\n", address)
// 				return
// 			}
// 			conn.Close()
// 			fmt.Printf("%s 打开了！！！\n", address)
// 		}(i)
// 	}
// 	wg.Wait()
// 	elapsed := time.Since(start) / 1e9
// 	fmt.Printf("\n\n%d seconds", elapsed)
// }
// func main() {
// 	for i := 21; i < 120; i++ {
// 		address := fmt.Sprintf("20.194.168.28:%d", i)
// 		conn, err := net.Dial("tcp", address)
// 		if err != nil {
// 			fmt.Printf("%s failed 关闭了\n", address)
// 			continue
// 		}
// 		conn.Close()
// 		fmt.Printf("%s connected 打开了！！！\n", address)
// 	}
// }