Init

Forward.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"golang.org/x/crypto/ssh"
+	"log"
+	"net"
+)
+
+func forward(localConn net.Conn, config *ssh.ClientConfig) {
+
+	sshClientConn, err := ssh.Dial("tcp", serverAddrString, config)
+	if err != nil {
+		log.Printf("ssh.Dial failed: %s\n", err)
+		return
+	}
+
+	if sshConn, err := sshClientConn.Dial("tcp", remoteAddrString); err != nil {
+		log.Println(`Was not able to create the tunnel: ` + err.Error())
+	} else {
+		go transfer(localConn, sshConn)
+		go transfer(sshConn, localConn)
+	}
+}

KeyboardInteractiveChallenge.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"log"
+)
+
+func keyboardInteractiveChallenge(user, instruction string, questions []string, echos []bool) (answers []string, err error) {
+
+	log.Println(`User: ` + user)
+	log.Println(`Instruction: ` + instruction)
+	log.Println(`Questions:`)
+	for q := range questions {
+		log.Println(q)
+	}
+
+	countQuestions := len(questions)
+	answers = make([]string, countQuestions, countQuestions)
+
+	if countQuestions > 0 {
+		answers[0] = password
+	}
+
+	err = nil
+	return
+}

Main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"golang.org/x/crypto/ssh"
+	"log"
+	"net"
+)
+
+func main() {
+
+	readFlags()
+	config := &ssh.ClientConfig{
+		User: username,
+		Auth: []ssh.AuthMethod{
+			ssh.Password(password),
+			ssh.PasswordCallback(passwordCallback),
+			ssh.KeyboardInteractive(keyboardInteractiveChallenge),
+		},
+	}
+
+	localListener, err := net.Listen(`tcp`, localAddrString)
+	if err != nil {
+		log.Printf("net.Listen failed: %v\n", err)
+	} else {
+		log.Println(`Listen to local address.`)
+	}
+
+	for {
+		localConn, err := localListener.Accept()
+		if err != nil {
+			log.Printf("listen.Accept failed: %v\n", err)
+		} else {
+			log.Println(`Accepted a client.`)
+			go forward(localConn, config)
+		}
+	}
+}

PasswordCallback.go

@@ -0,0 +1,5 @@
+package main
+
+func passwordCallback() (string, error) {
+	return password, nil
+}

ReadFlags.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"flag"
+)
+
+func readFlags() {
+	flag.StringVar(&serverAddrString, `server`, `127.0.0.1:22`, `The (remote) SSH server, e.g. 'my.host.com', 'my.host.com:22', '127.0.0.1:22', 'localhost:22'.`)
+	flag.StringVar(&localAddrString, `local`, `127.0.0.1:50000`, `The local end-point of the tunnel, e.g. '127.0.0.1:50000', 'localhost:50000'.`)
+	flag.StringVar(&remoteAddrString, `remote`, `127.0.0.1:27017`, `The remote side end-point (e.g. on the machine with the SSH server), e.g. a MongoDB (port 27017) '127.0.0.1:27017', a web server '127.0.0.1:80'`)
+	flag.StringVar(&username, `user`, `username`, `The user's name for the SSD server.`)
+	flag.StringVar(&password, `pwd`, `password`, `The user's password for the SSD server.`)
+	flag.Parse()
+}

Transfer.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"io"
+	"log"
+)
+
+func transfer(fromReader io.Reader, toWriter io.Writer) {
+
+	if _, err := io.Copy(toWriter, fromReader); err != nil {
+		log.Printf("io.Copy failed: %v\n", err)
+	} else {
+		log.Println(`Transfer closed.`)
+	}
+}

Variables.go

@@ -0,0 +1,9 @@
+package main
+
+var (
+	username         = "name"
+	password         = "pwd"
+	serverAddrString = "server:22"
+	localAddrString  = "localhost:53001"
+	remoteAddrString = "localhost:27017"
+)