Version 1.2.0

Main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/SommerEngineering/SSHTunnel/Tunnel"
 	"golang.org/x/crypto/ssh"
 	"runtime"
 )
@@ -9,7 +10,7 @@ import (
 func main() {
 
 	// Show the current version:
-	fmt.Println(`SSHTunnel v1.1.0`)
+	fmt.Println(`SSHTunnel v1.2.0`)
 
 	// Allow Go to use all CPUs:
 	runtime.GOMAXPROCS(runtime.NumCPU())
@@ -29,18 +30,19 @@ func main() {
 	}
 
 	// Create the SSH configuration:
+	Tunnel.SetPassword4Callback(password)
 	config := &ssh.ClientConfig{
 		User: username,
 		Auth: []ssh.AuthMethod{
 			ssh.Password(password),
-			ssh.PasswordCallback(passwordCallback),
+			ssh.PasswordCallback(Tunnel.PasswordCallback),
-			ssh.KeyboardInteractive(keyboardInteractiveChallenge),
+			ssh.KeyboardInteractive(Tunnel.KeyboardInteractiveChallenge),
 		},
 	}
 
 	// Create the local end-point:
-	localListener := createLocalEndPoint()
+	localListener := Tunnel.CreateLocalEndPoint(localAddrString)
 
 	// Accept client connections (will block forever):
-	acceptClients(localListener, config)
+	Tunnel.AcceptClients(localListener, config, serverAddrString, remoteAddrString)
 }

PasswordCallback.go

@@ -1,6 +0,0 @@
-package main
-
-// Just a callback function for the password request.
-func passwordCallback() (string, error) {
-	return password, nil
-}

Tunnel/AcceptClients.go

@@ -1,28 +1,28 @@
-package main
+package Tunnel
-
+
-import (
+import (
-	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh"
-	"log"
+	"log"
-	"net"
+	"net"
-)
+)
-
+
-func acceptClients(connection net.Listener, config *ssh.ClientConfig) {
+func AcceptClients(connection net.Listener, config *ssh.ClientConfig, serverAddrString, remoteAddrString string) {
-
+
-	// Endless loop
+	// Endless loop
-	for {
+	for {
-
+
-		// Accept (another) client connection:
+		// Accept (another) client connection:
-		if localConn, err := connection.Accept(); err != nil {
+		if localConn, err := connection.Accept(); err != nil {
-
+
-			// Fail
+			// Fail
-			log.Printf("Accepting a client failed: %s\n", err.Error())
+			log.Printf("Accepting a client failed: %s\n", err.Error())
-		} else {
+		} else {
-
+
-			// Success
+			// Success
-			log.Println(`Client accepted.`)
+			log.Println(`Client accepted.`)
-
+
-			// Start the forwarding:
+			// Start the forwarding:
-			go forward(localConn, config)
+			go forward(localConn, config, serverAddrString, remoteAddrString)
-		}
+		}
-	}
+	}
-}
+}

Tunnel/Constants.go

@@ -1,7 +1,7 @@
-package main
+package Tunnel
-
+
-const (
+const (
-	maxRetriesLocal  = 16 // How many retries are allowed to create the local end-point?
+	maxRetriesLocal  = 16 // How many retries are allowed to create the local end-point?
-	maxRetriesRemote = 16 // How many retries are allowed to create the remote end-point?
+	maxRetriesRemote = 16 // How many retries are allowed to create the remote end-point?
-	maxRetriesServer = 16 // How many retries are allowed to create the SSH server's connection?
+	maxRetriesServer = 16 // How many retries are allowed to create the SSH server's connection?
-)
+)

Tunnel/CreateLocalEndPoint.go

@@ -1,35 +1,35 @@
-package main
+package Tunnel
-
+
-import (
+import (
-	"log"
+	"log"
-	"net"
+	"net"
-	"time"
+	"time"
-)
+)
-
+
-func createLocalEndPoint() (localListener net.Listener) {
+func CreateLocalEndPoint(localAddrString string) (localListener net.Listener) {
-
+
-	// Loop for the necessary retries
+	// Loop for the necessary retries
-	for {
+	for {
-
+
-		// Try to create the local end-point
+		// Try to create the local end-point
-		if localListenerObj, err := net.Listen(`tcp`, localAddrString); err != nil {
+		if localListenerObj, err := net.Listen(`tcp`, localAddrString); err != nil {
-
+
-			// It was not able to create the end-point:
+			// It was not able to create the end-point:
-			currentRetriesLocal++
+			currentRetriesLocal++
-			log.Printf("Was not able to create the local end-point %s: %s\n", localAddrString, err.Error())
+			log.Printf("Was not able to create the local end-point %s: %s\n", localAddrString, err.Error())
-
+
-			// Is another retry possible?
+			// Is another retry possible?
-			if currentRetriesLocal < maxRetriesLocal {
+			if currentRetriesLocal < maxRetriesLocal {
-				log.Println(`Retry...`)
+				log.Println(`Retry...`)
-				time.Sleep(1 * time.Second)
+				time.Sleep(1 * time.Second)
-			} else {
+			} else {
-				log.Fatalln(`No more retries for the local end-point: ` + localAddrString) // => Exit
+				log.Fatalln(`No more retries for the local end-point: ` + localAddrString) // => Exit
-			}
+			}
-		} else {
+		} else {
-			// Success!
+			// Success!
-			log.Println(`Listen to local address ` + localAddrString)
+			log.Println(`Listen to local address ` + localAddrString)
-			localListener = localListenerObj
+			localListener = localListenerObj
-			return
+			return
-		}
+		}
-	}
+	}
-}
+}

Tunnel/Forward.go

@@ -1,97 +1,97 @@
-package main
+package Tunnel
-
+
-import (
+import (
-	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh"
-	"log"
+	"log"
-	"net"
+	"net"
-	"time"
+	"time"
-)
+)
-
+
-func forward(localConn net.Conn, config *ssh.ClientConfig) {
+func forward(localConn net.Conn, config *ssh.ClientConfig, serverAddrString, remoteAddrString string) {
-
+
-	defer localConn.Close()
+	defer localConn.Close()
-	currentRetriesServer := 0
+	currentRetriesServer := 0
-	currentRetriesRemote := 0
+	currentRetriesRemote := 0
-	var sshClientConnection *ssh.Client = nil
+	var sshClientConnection *ssh.Client = nil
-
+
-	// Loop for retries:
+	// Loop for retries:
-	for {
+	for {
-
+
-		// Try to connect to the SSH server:
+		// Try to connect to the SSH server:
-		if sshClientConn, err := ssh.Dial(`tcp`, serverAddrString, config); err != nil {
+		if sshClientConn, err := ssh.Dial(`tcp`, serverAddrString, config); err != nil {
-
+
-			// Failed:
+			// Failed:
-			currentRetriesServer++
+			currentRetriesServer++
-			log.Printf("Was not able to connect with the SSH server %s: %s\n", serverAddrString, err.Error())
+			log.Printf("Was not able to connect with the SSH server %s: %s\n", serverAddrString, err.Error())
-
+
-			// Is a retry alowed?
+			// Is a retry alowed?
-			if currentRetriesServer < maxRetriesServer {
+			if currentRetriesServer < maxRetriesServer {
-				log.Println(`Retry...`)
+				log.Println(`Retry...`)
-				time.Sleep(1 * time.Second)
+				time.Sleep(1 * time.Second)
-			} else {
+			} else {
-
+
-				// After the return, this thread is closed down. The client can try it again...
+				// After the return, this thread is closed down. The client can try it again...
-				log.Println(`No more retries for connecting the SSH server.`)
+				log.Println(`No more retries for connecting the SSH server.`)
-				return
+				return
-			}
+			}
-
+
-		} else {
+		} else {
-
+
-			// Success:
+			// Success:
-			log.Println(`Connected to the SSH server ` + serverAddrString)
+			log.Println(`Connected to the SSH server ` + serverAddrString)
-			sshClientConnection = sshClientConn
+			sshClientConnection = sshClientConn
-			defer sshClientConnection.Close()
+			defer sshClientConnection.Close()
-			break
+			break
-		}
+		}
-	}
+	}
-
+
-	// Loop for retries:
+	// Loop for retries:
-	for {
+	for {
-
+
-		// Try to create the remote end-point:
+		// Try to create the remote end-point:
-		if sshConn, err := sshClientConnection.Dial(`tcp`, remoteAddrString); err != nil {
+		if sshConn, err := sshClientConnection.Dial(`tcp`, remoteAddrString); err != nil {
-
+
-			// Failed:
+			// Failed:
-			currentRetriesRemote++
+			currentRetriesRemote++
-			log.Printf("Was not able to create the remote end-point %s: %s\n", remoteAddrString, err.Error())
+			log.Printf("Was not able to create the remote end-point %s: %s\n", remoteAddrString, err.Error())
-
+
-			// Is another retry allowed?
+			// Is another retry allowed?
-			if currentRetriesRemote < maxRetriesRemote {
+			if currentRetriesRemote < maxRetriesRemote {
-				log.Println(`Retry...`)
+				log.Println(`Retry...`)
-				time.Sleep(1 * time.Second)
+				time.Sleep(1 * time.Second)
-			} else {
+			} else {
-
+
-				// After the return, this thread is closed down. The client can try it again...
+				// After the return, this thread is closed down. The client can try it again...
-				log.Println(`No more retries for connecting the remote end-point.`)
+				log.Println(`No more retries for connecting the remote end-point.`)
-				return
+				return
-			}
+			}
-		} else {
+		} else {
-
+
-			// Fine, the connections are up and ready :-)
+			// Fine, the connections are up and ready :-)
-			log.Printf("The remote end-point %s is connected.\n", remoteAddrString)
+			log.Printf("The remote end-point %s is connected.\n", remoteAddrString)
-			defer sshConn.Close()
+			defer sshConn.Close()
-
+
-			// To be able to close down both transfer threads, we create a channel:
+			// To be able to close down both transfer threads, we create a channel:
-			quit := make(chan bool)
+			quit := make(chan bool)
-
+
-			// Create the transfers to/from both sides (two new threads are created for this):
+			// Create the transfers to/from both sides (two new threads are created for this):
-			go transfer(localConn, sshConn, `Local => Remote`, quit)
+			go transfer(localConn, sshConn, `Local => Remote`, quit)
-			go transfer(sshConn, localConn, `Remote => Local`, quit)
+			go transfer(sshConn, localConn, `Remote => Local`, quit)
-
+
-			// Wait and look if any of the two transfer theads are down:
+			// Wait and look if any of the two transfer theads are down:
-			isRunning := true
+			isRunning := true
-			for isRunning {
+			for isRunning {
-				select {
+				select {
-				case <-quit:
+				case <-quit:
-					log.Println(`At least one transfer was stopped.`)
+					log.Println(`At least one transfer was stopped.`)
-					isRunning = false
+					isRunning = false
-					break
+					break
-				}
+				}
-			}
+			}
-
+
-			// Now, close all the channels and therefore, force the other / second thread to go down:
+			// Now, close all the channels and therefore, force the other / second thread to go down:
-			log.Println(`Close now all connections.`)
+			log.Println(`Close now all connections.`)
-			return
+			return
-		}
+		}
-	}
+	}
-}
+}

Tunnel/KeyboardInteractiveChallenge.go

@@ -1,35 +1,35 @@
-package main
+package Tunnel
-
+
-import (
+import (
-	"log"
+	"log"
-)
+)
-
+
-// Another auth. method.
+// Another auth. method.
-func keyboardInteractiveChallenge(user, instruction string, questions []string, echos []bool) (answers []string, err error) {
+func KeyboardInteractiveChallenge(user, instruction string, questions []string, echos []bool) (answers []string, err error) {
-
+
-	// Log all the provided data:
+	// Log all the provided data:
-	log.Println(`User: ` + user)
+	log.Println(`User: ` + user)
-	log.Println(`Instruction: ` + instruction)
+	log.Println(`Instruction: ` + instruction)
-	log.Println(`Questions:`)
+	log.Println(`Questions:`)
-	for q := range questions {
+	for q := range questions {
-		log.Println(q)
+		log.Println(q)
-	}
+	}
-
+
-	// How many questions are asked?
+	// How many questions are asked?
-	countQuestions := len(questions)
+	countQuestions := len(questions)
-
+
-	if countQuestions == 1 {
+	if countQuestions == 1 {
-
+
-		// We expect that in this case (only one question is asked), that the server want to know the password ;-)
+		// We expect that in this case (only one question is asked), that the server want to know the password ;-)
-		answers = make([]string, countQuestions, countQuestions)
+		answers = make([]string, countQuestions, countQuestions)
-		answers[0] = password
+		answers[0] = callbackPassword
-
+
-	} else if countQuestions > 1 {
+	} else if countQuestions > 1 {
-
+
-		// After logging, this call will exit the whole program:
+		// After logging, this call will exit the whole program:
-		log.Fatalln(`The SSH server is asking multiple questions! This program cannot handle this case.`)
+		log.Fatalln(`The SSH server is asking multiple questions! This program cannot handle this case.`)
-	}
+	}
-
+
-	err = nil
+	err = nil
-	return
+	return
-}
+}

Tunnel/PasswordCallback.go

@@ -0,0 +1,10 @@
+package Tunnel
+
+// Just a callback function for the password request.
+func PasswordCallback() (string, error) {
+	return callbackPassword, nil
+}
+
+func SetPassword4Callback(password string) {
+	callbackPassword = password
+}

Tunnel/Transfer.go

@@ -1,27 +1,27 @@
-package main
+package Tunnel
-
+
-import (
+import (
-	"io"
+	"io"
-	"log"
+	"log"
-)
+)
-
+
-// The transfer function.
+// The transfer function.
-func transfer(fromReader io.Reader, toWriter io.Writer, name string, quit chan bool) {
+func transfer(fromReader io.Reader, toWriter io.Writer, name string, quit chan bool) {
-
+
-	log.Printf("%s transfer started.", name)
+	log.Printf("%s transfer started.", name)
-
+
-	// This call blocks until the client or service will close the connection.
+	// This call blocks until the client or service will close the connection.
-	// Therefore, this call maybe takes hours or even longer. Concern, may this
+	// Therefore, this call maybe takes hours or even longer. Concern, may this
-	// program will be used to connect multiple servers to make e.g. a database
+	// program will be used to connect multiple servers to make e.g. a database
-	// available...
+	// available...
-	if _, err := io.Copy(toWriter, fromReader); err != nil {
+	if _, err := io.Copy(toWriter, fromReader); err != nil {
-
+
-		// In this case, we do not fail the whole program: Regarding how the client
+		// In this case, we do not fail the whole program: Regarding how the client
-		// or the service was e.g. shut down, the error may only means 'client has been closed'.
+		// or the service was e.g. shut down, the error may only means 'client has been closed'.
-		log.Printf("%s transfer failed: %s\n", name, err.Error())
+		log.Printf("%s transfer failed: %s\n", name, err.Error())
-	} else {
+	} else {
-		log.Printf("%s transfer closed.\n", name)
+		log.Printf("%s transfer closed.\n", name)
-	}
+	}
-
+
-	quit <- true
+	quit <- true
-}
+}

Tunnel/Variables.go

@@ -0,0 +1,6 @@
+package Tunnel
+
+var (
+	currentRetriesLocal = 0 // Check how many retries are occur for creating the local end-point
+	callbackPassword    = ``
+)

Variables.go

@@ -1,10 +1,9 @@
 package main
 
 var (
-	username            = `` // The SSH user's name
+	username         = `` // The SSH user's name
-	password            = `` // The user's password
+	password         = `` // The user's password
-	serverAddrString    = `` // The SSH server address
+	serverAddrString = `` // The SSH server address
-	localAddrString     = `` // The local end-point
+	localAddrString  = `` // The local end-point
-	remoteAddrString    = `` // The remote end-point (on the SSH server's side)
+	remoteAddrString = `` // The remote end-point (on the SSH server's side)
-	currentRetriesLocal = 0  // Check how many retries are occur for creating the local end-point
 )