go的ssh tunnel

该链接为讲解

https://elliotchance.medium.com/how-to-create-an-ssh-tunnel-in-go-b63722d682aa

package main
import (
    "fmt"
    "golang.org/x/crypto/ssh"
    "io"
    "io/ioutil"
    "log"
    "net"
    "strconv"
    "strings"
)
type Endpoint struct {
    Host string
    Port int
    User string
}
func NewEndpoint(s string) *Endpoint {
    endpoint := &Endpoint{
        Host: s,
    }
    if parts := strings.Split(endpoint.Host, "@"); len(parts) > 1 {
        endpoint.User = parts[0]
        endpoint.Host = parts[1]
    }
    if parts := strings.Split(endpoint.Host, ":"); len(parts) > 1 {
        endpoint.Host = parts[0]
        endpoint.Port, _ = strconv.Atoi(parts[1])
    }
    return endpoint
}
func (endpoint *Endpoint) String() string {
    return fmt.Sprintf("%s:%d", endpoint.Host, endpoint.Port)
}
type SSHTunnel struct {
    Local  *Endpoint
    Server *Endpoint
    Remote *Endpoint
    Config *ssh.ClientConfig
    Log    *log.Logger
}
func (tunnel *SSHTunnel) logf(fmt string, args ...interface{}) {
    if tunnel.Log != nil {
        tunnel.Log.Printf(fmt, args...)
    }
}
func (tunnel *SSHTunnel) Start() error {
    listener, err := net.Listen("tcp", tunnel.Local.String())
    if err != nil {
        return err
    }
    defer listener.Close()
    tunnel.Local.Port = listener.Addr().(*net.TCPAddr).Port
    for {
        conn, err := listener.Accept()
        if err != nil {
            return err
        }
        tunnel.logf("accepted connection")
        go tunnel.forward(conn)
    }
}
func (tunnel *SSHTunnel) forward(localConn net.Conn) {
    serverConn, err := ssh.Dial("tcp", tunnel.Server.String(), tunnel.Config)
    if err != nil {
        tunnel.logf("server dial error: %s", err)
        return
    }
    tunnel.logf("connected to %s (1 of 2)\n", tunnel.Server.String())
    remoteConn, err := serverConn.Dial("tcp", tunnel.Remote.String())
    if err != nil {
        tunnel.logf("remote dial error: %s", err)
        return
    }
    tunnel.logf("connected to %s (2 of 2)\n", tunnel.Remote.String())
    copyConn := func(writer, reader net.Conn) {
        _, err := io.Copy(writer, reader)
        if err != nil {
            tunnel.logf("io.Copy error: %s", err)
        }
    }
    go copyConn(localConn, remoteConn)
    go copyConn(remoteConn, localConn)
}
func PrivateKeyFile(file string) ssh.AuthMethod {
    buffer, err := ioutil.ReadFile(file)
    if err != nil {
        return nil
    }
    key, err := ssh.ParsePrivateKey(buffer)
    if err != nil {
        return nil
    }
    return ssh.PublicKeys(key)
}
func NewSSHTunnel(tunnel string, auth ssh.AuthMethod, destination string) *SSHTunnel {
    // A random port will be chosen for us.
    localEndpoint := NewEndpoint("localhost:0")
    server := NewEndpoint(tunnel)
    if server.Port == 0 {
        server.Port = 22
    }
    sshTunnel := &SSHTunnel{
        Config: &ssh.ClientConfig{
            User: server.User,
            Auth: []ssh.AuthMethod{auth},
            HostKeyCallback: func(hostname string, remote net.Addr, key ssh.PublicKey) error {
                // Always accept key.
                return nil
            },
        },
        Local:  localEndpoint,
        Server: server,
        Remote: NewEndpoint(destination),
    }
    return sshTunnel
}

　　应用实例：

func main() {
   // Setup the tunnel, but do not yet start it yet.
   tunnel := NewSSHTunnel(
      // User and host of tunnel server, it will default to port 22
      // if not specified.
      "ec2-user@jumpbox.us-east-1.mydomain.com",
      // Pick ONE of the following authentication methods:
      PrivateKeyFile("path/to/private/key.pem"), // 1. private key
      ssh.Password("password"),                  // 2. password
      // The destination host and port of the actual server.
      "dqrsdfdssdfx.us-east-1.redshift.amazonaws.com:5439",
   )
   // You can provide a logger for debugging, or remove this line to
   // make it silent.
   tunnel.Log = log.New(os.Stdout, "", log.Ldate | log.Lmicroseconds)
   // Start the server in the background. You will need to wait a
   // small amount of time for it to bind to the localhost port
   // before you can start sending connections.
   go tunnel.Start()
   time.Sleep(100 * time.Millisecond)
   // NewSSHTunnel will bind to a random port so that you can have
   // multiple SSH tunnels available. The port is available through:
   //   tunnel.Local.Port
   
   // You can use any normal Go code to connect to the destination
   // server through localhost. You may need to use 127.0.0.1 for
   // some libraries.
   //
   // Here is an example of connecting to a PostgreSQL server:
   conn := fmt.Sprintf("host=127.0.0.1 port=%d username=foo", tunnel.Local.Port)
   db, err := sql.Open("postgres", conn)
   // ...
}

　　更方便的包：

https://github.com/elliotchance/sshtunnel