golang SSH客户端三件套 - 2端口映射 port forward

golang SSH客户端系列文章目录

1. 远程登录
2. 端口映射
3. 文件传输

SSH端口映射的例子，通过创建ssh隧道，将远程服务器上的5900端口映射到本地的5900端口

package main

import (
    "fmt"
    "golang.org/x/crypto/ssh"
    "io"
    "log"
    "net"
    "sync"
    "time"
)

const (
    //本地监听地址
    laddr = "localhost:5900"
    //远程服务地址
    raddr   = "localhost:5900"
    sshaddr = "192.168.1.8:22"
)

/**
基于ssh连接的端口转发
https://tools.ietf.org/html/rfc4254#page-16 TCP/IP Port Forwarding

通过ssh隧道将远程服务器(192.168.1.8)上的5900端口映射到本地5900端口
*/
func main() {

    sshConfig := &ssh.ClientConfig{
        User: "user",
        Auth: []ssh.AuthMethod{
            ssh.Password("123456"),
        },
        HostKeyCallback: ssh.InsecureIgnoreHostKey(),
        ClientVersion:   "",
        Timeout:         10 * time.Second,
    }

    //监听本地映射端口
    listener, err := net.Listen("tcp", laddr)
    if err != nil {
        log.Fatalln(err.Error())
    }
    defer listener.Close()
    for {
        conn, err := listener.Accept()
        if err != nil {
            log.Println(err)
            continue
        }
        //客户端连接
        go portForward(conn, sshConfig)
    }
}

/**
conn: 客户端到本地映射端口的连接
sshConfig: ssh配置
*/
func portForward(conn net.Conn, sshConfig *ssh.ClientConfig) {
    defer conn.Close()

    //建立与SSH服务器的连接
    sshClient, err := ssh.Dial("tcp", sshaddr, sshConfig)
    if err != nil {
        log.Fatalln(err.Error())
    }
    defer sshClient.Close()

    //建立ssh到后端服务的连接
    forwardConn, err := sshClient.Dial("tcp", raddr)
    if err != nil {
        log.Fatalln(err.Error())
    }

    log.Println("ssh端口映射隧道建立成功")

    defer forwardConn.Close()

    var wait2close = sync.WaitGroup{}
    wait2close.Add(1)

    go func() {
        n, err := io.Copy(forwardConn, conn)
        if err != nil {
            log.Fatalln(err.Error())
            wait2close.Done()
        }
        log.Printf("入流量共%s", formatFlowSize(n))
    }()

    go func() {
        n, err := io.Copy(conn, forwardConn)
        if err != nil {
            log.Fatalln(err.Error())
            wait2close.Done()
        }
        log.Printf("出流量共%s", formatFlowSize(n))
    }()

    wait2close.Wait()
    log.Println("ssh端口映射隧道关闭")
}

// 字节的单位转换 保留两位小数
func formatFlowSize(s int64) (size string) {
    if s < 1024 {
        return fmt.Sprintf("%.2fB", float64(s)/float64(1))
    } else if s < (1024 * 1024) {
        return fmt.Sprintf("%.2fKB", float64(s)/float64(1024))
    } else if s < (1024 * 1024 * 1024) {
        return fmt.Sprintf("%.2fMB", float64(s)/float64(1024*1024))
    } else if s < (1024 * 1024 * 1024 * 1024) {
        return fmt.Sprintf("%.2fGB", float64(s)/float64(1024*1024*1024))
    } else if s < (1024 * 1024 * 1024 * 1024 * 1024) {
        return fmt.Sprintf("%.2fTB", float64(s)/float64(1024*1024*1024*1024))
    } else { //if s < (1024 * 1024 * 1024 * 1024 * 1024 * 1024)
        return fmt.Sprintf("%.2fEB", float64(s)/float64(1024*1024*1024*1024*1024))
    }
}