sshforward

README

SSH Port Forwarding Package

A Go package that provides SSH port forwarding functionality with support for both local-to-remote and remote-to-local port forwarding.

Features

• Local to remote port forwarding
• Remote to local port forwarding
• Event notification system
• Automatic retry on connection failure
• Concurrent connection handling
• State management

Installation

go get github.com/yourusername/sshforward

Usage

Basic Setup

import (
    "github.com/yourusername/sshforward"
    "golang.org/x/crypto/ssh"
)

// Create a new forward instance
forward := sshforward.CreateForward()

// Configure SSH client
sshConfig := &ssh.ClientConfig{
    User: "username",
    Auth: []ssh.AuthMethod{
        ssh.Password("password"),
        // or use ssh.PublicKeys(...)
    },
    HostKeyCallback: ssh.InsecureIgnoreHostKey(),
}

// Configure the tunnel
forward.ConfigTunnel(sshConfig, "example.com", "22")

Starting Port Forwarding

Local to Remote Port Forwarding

// Forward local port 8080 to remote port 80
forward.Service(sshforward.FORWARD_TYPE_LOCAL_TO_REMOTE_LISTEN, "80", "8080")

// Wait for the forwarding to be ready
forward.Wait()

// Now the port forwarding is ready to use

Remote to Local Port Forwarding

// Forward remote port 80 to local port 8080
forward.Service(sshforward.FORWARD_TYPE_REMOTE_TO_LOCAL_LISTEN, "80", "8080")

// Wait for the forwarding to be ready
forward.Wait()

// Now the port forwarding is ready to use

Event Monitoring

// Get the event notification channel
eventChan := forward.EventNotifyChannel()

// Monitor events
go func() {
    for event := range eventChan {
        fmt.Printf("State: %s, Time: %s, Message: %s\n",
            event.State, event.T.Format(time.RFC3339), event.Msg)
    }
}()

States

The forwarding service can be in following states:

• NONE: Initial state
• CONFIGURED: SSH configuration completed
• STARTING: Service is starting
• SSH_CONNECTED: SSH connection established and ready for use
• STOPPED: Service stopped
• SKIP: Service skipped (e.g., port unavailable)
• ERROR: Error occurred
• RETRY: Service is retrying after failure

Complete Example

package main

import (
    "fmt"
    "time"
    "github.com/yourusername/sshforward"
    "golang.org/x/crypto/ssh"
)

func main() {
    // Create and configure forward
    forward := sshforward.CreateForward()
    
    sshConfig := &ssh.ClientConfig{
        User: "username",
        Auth: []ssh.AuthMethod{
            ssh.Password("password"),
        },
        HostKeyCallback: ssh.InsecureIgnoreHostKey(),
    }
    
    forward.ConfigTunnel(sshConfig, "example.com", "22")
    
    // Monitor events
    go func() {
        for event := range forward.EventNotifyChannel() {
            fmt.Printf("[%s] %s: %s\n", 
                event.T.Format(time.RFC3339),
                event.State,
                event.Msg)
        }
    }()
    
    // Start forwarding
    forward.Service(sshforward.FORWARD_TYPE_LOCAL_TO_REMOTE_LISTEN, "80", "8080")
    
    // Wait for forwarding to be ready
    forward.Wait()
    
    fmt.Println("Port forwarding is now ready to use!")
    
    // Keep the program running
    select {}
}

Error Handling

The service automatically retries on connection failures with a 10-second delay. Error messages are sent through the event notification channel.

Notes

• Ensure the target ports are available before starting the service
• The service runs in a separate goroutine
• The event channel has a buffer size of 10
• For remote to local forwarding, the local port availability is checked before starting
• Wait() blocks until the SSH forwarding is ready to use
• The service will continue running in the background after Wait() returns

Documentation

Index

• Constants
• type ForwardConfig_t
  • func CreateForward() *ForwardConfig_t
  • func (f *ForwardConfig_t) Close()
  • func (f *ForwardConfig_t) ConfigTunnel(sshConfig *ssh.ClientConfig, tunnelAddr string, tunnelPort string)
  • func (f *ForwardConfig_t) EventNotifyChannel() <-chan StateEvent_t
  • func (f *ForwardConfig_t) Service(t ForwardType_t, remotePort, localPort string)
  • func (f *ForwardConfig_t) Wait()
• type ForwardType_t
• type StateEvent_t

Constants

const (
	FORWARD_STATE_NONE forwardState_t = iota
	FORWARD_STATE_CONFIGURED
	FORWARD_STATE_STARTING
	FORWARD_STATE_SSH_CONNECTED
	FORWARD_STATE_STOPPED
	FORWARD_STATE_SKIP
	FORWARD_STATE_ERROR
	FORWARD_STATE_RETRY
)

Types

type ForwardConfig_t

type ForwardConfig_t struct {
	// contains filtered or unexported fields
}

func CreateForward

func CreateForward() *ForwardConfig_t

func (*ForwardConfig_t) Close

func (f *ForwardConfig_t) Close()

func (*ForwardConfig_t) ConfigTunnel

func (f *ForwardConfig_t) ConfigTunnel(sshConfig *ssh.ClientConfig, tunnelAddr string, tunnelPort string)

func (*ForwardConfig_t) EventNotifyChannel

func (f *ForwardConfig_t) EventNotifyChannel() <-chan StateEvent_t

func (*ForwardConfig_t) Service

func (f *ForwardConfig_t) Service(t ForwardType_t, remotePort, localPort string)

func (*ForwardConfig_t) Wait

func (f *ForwardConfig_t) Wait()

type ForwardType_t

type ForwardType_t int

const (
	FORWARD_TYPE_LOCAL_TO_REMOTE_LISTEN ForwardType_t = iota
	FORWARD_TYPE_REMOTE_TO_LOCAL_LISTEN
)

type StateEvent_t

type StateEvent_t struct {
	State string
	T     time.Time
	Msg   string
}