goでsshでシェルに接続しport forwardする検証・サンプルコード

ssh_term_portforward.go

package main

import (
	"fmt"
	"io"
	"net"
	"os"
	"os/signal"
	"syscall"

	"golang.org/x/crypto/ssh"
	"golang.org/x/crypto/ssh/terminal"
)

var (
	host       = "targethost"
	port       = "22"
	user       = "user"
	pass       = "password"
	localPort  = "localhost:10022"
	remotePort = "localhost:22"
)

func forward(localConn net.Conn, config *ssh.ClientConfig) {
	// Setup sshClientConn (type *ssh.ClientConn)
	sshClientConn, err := ssh.Dial("tcp", host+":"+port, config)
	if err != nil {
		fmt.Println("ssh.Dial failed: %s", err)
	}

	// Setup sshConn (type net.Conn)
	sshConn, err := sshClientConn.Dial("tcp", remotePort)

	// Copy localConn.Reader to sshConn.Writer
	go func() {
		_, err = io.Copy(sshConn, localConn)
		if err != nil {
			fmt.Println("io.Copy failed: %v", err)
		}
	}()

	// Copy sshConn.Reader to localConn.Writer
	go func() {
		_, err = io.Copy(localConn, sshConn)
		if err != nil {
			fmt.Println("io.Copy failed: %v", err)
		}
	}()
}

func main() {
	// Create sshClientConfig
	sshConfig := &ssh.ClientConfig{
		User: user,
		Auth: []ssh.AuthMethod{
			ssh.Password(pass),
		},
		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
	}

	// Setup localListener (type net.Listener)
	localListener, err := net.Listen("tcp", localPort)
	if err != nil {
		fmt.Println("net.Listen failed: %v", err)
	} else {
		go func() {
			for {
				// Setup localConn (type net.Conn)
				localConn, err := localListener.Accept()
				if err != nil {
					fmt.Println("listen.Accept failed: %v", err)
				}
				go forward(localConn, sshConfig)
			}
		}()
	}

	// SSH connect.
	client, err := ssh.Dial("tcp", host+":"+port, sshConfig)

	// Create Session
	session, err := client.NewSession()
	defer session.Close()

	// キー入力を接続先が認識できる形式に変換する(ここがキモ)
	fd := int(os.Stdin.Fd())
	state, err := terminal.MakeRaw(fd)
	if err != nil {
		fmt.Println(err)
	}
	defer terminal.Restore(fd, state)

	// ターミナルサイズの取得
	w, h, err := terminal.GetSize(fd)
	if err != nil {
		fmt.Println(err)
	}

	modes := ssh.TerminalModes{
		ssh.ECHO:          1,
		ssh.TTY_OP_ISPEED: 14400,
		ssh.TTY_OP_OSPEED: 14400,
	}

	err = session.RequestPty("xterm", h, w, modes)
	if err != nil {
		fmt.Println(err)
	}

	session.Stdout = os.Stdout
	session.Stderr = os.Stderr
	session.Stdin = os.Stdin

	err = session.Shell()
	if err != nil {
		fmt.Println(err)
	}

	// ターミナルサイズの変更検知・処理
	signal_chan := make(chan os.Signal, 1)
	signal.Notify(signal_chan, syscall.SIGWINCH)
	go func() {
		for {
			s := <-signal_chan
			switch s {
			case syscall.SIGWINCH:
				fd := int(os.Stdout.Fd())
				w, h, _ = terminal.GetSize(fd)
				session.WindowChange(h, w)
			}
		}
	}()

	err = session.Wait()
	if err != nil {
		fmt.Println(err)
	}
}