sshow

README

sshow is a Go library to facilitate p2p ssh connections to help diagnose problems on coworkers computers when everyone is distributed and behind restrictive VPNs. There are example commands that may be used directly in ./cmd although these will likely be to limited and you may want to reimplement them in your own projects.

This project uses and/or adapts various awesome projects:

• https://github.com/pion/webrtc
• https://github.com/pion/turn
• https://github.com/nobonobo/ssh-p2p
• https://github.com/gliderlabs/ssh

WARNING: the code is a proof of concept, error handling needs to be cleaned up.

The provided command line can be installed like:

go install github.com/coryb/sshow/cmd/sshow@latest

Enable inbound connections

The installed sshow tool can be useful for experimenting. The "target" system where to allow incoming connections would run:

sshow server

2022/10/30 22:26:53 Session Key: ba9c92a1-27c6-4e3b-8b6e-3ebad7a44240
2022/10/30 22:26:53 starting ssh server on port 63085...

The session key will need to be shared with the client for the ssh to negotiate to the server. The SSH server is started on the loopback network on a random available network port.

Connecting to target

To connect to the target system you would use:

sshow ssh -key ba9c92a1-27c6-4e3b-8b6e-3ebad7a44240

2022/10/30 22:52:41 Client connect done
$ 

The shell is now on the remote target system. When you exit the bash terminal (bash -l is run by default on connection) then the client disconnect.

Signal Broker

By default the sshow server and sshow ssh command use hosted projects (not affiliated with this project) for the STUN service and for the Signaling service. The hosts used by default are: stun.l.google.com:19302 for STUN and https://nobo-signaling.appspot.com for Signalling. The later is maintained by the author of https://github.com/nobonobo/ssh-p2p.

If you want to host your own STUN and Signaling service, you can use use this project. When you run:

sshow broker

It will start a STUN/TURN service on port 3478 on all available IP addresses. It will also start an HTTP service for Signaling on port 8080.

To use these services, you would run the sshow server on like:

sshow server --stun localhost:3478 --signal http://localhost:8080

And the client would run:

sshow ssh --stun localhost:3478 --signal http://localhost:8080 --key ba9c92a1-27c6-4e3b-8b6e-3ebad7a44240

This example is not terribly useful, as you can only connect to localhost from localhost. If the sshow broker command was run on a hosted server inside a corporate network, then your and your coworkers should be able to use it by using the hosted STUN and signal hosts.

Documentation

Index

• func BrokerRun(ctx context.Context, opts BrokerRunOptions) error
• func ClientRun(ctx context.Context, opts ClientRunOptions) error
• func Serve(ctx context.Context, key, addr string) error
• func ServerRun(ctx context.Context, opts ServerRunOptions) error
• func StartClient(ctx context.Context, key string, sock net.Conn) error
• func StartSSHD(ctx context.Context, sshCmd string, mirrorSession bool, portCh chan<- int) error
• func StartSignalServer(ctx context.Context, port int) error
• func StartTurnServer(ctx context.Context, port int, addresses []string) error
• func WithLogger(ctx context.Context, l Logger) context.Context
• type BrokerRunOptions
• type ClientRunOptions
• type ConnectInfo
• type DebugLogger
  • func (l DebugLogger) Debugf(format string, v ...any)
• type Logger
  • func Log(ctx context.Context) Logger
• type ServerRunOptions

Functions

func BrokerRun

func BrokerRun(ctx context.Context, opts BrokerRunOptions) error

func ClientRun

func ClientRun(ctx context.Context, opts ClientRunOptions) error

func Serve

func Serve(ctx context.Context, key, addr string) error

func ServerRun

func ServerRun(ctx context.Context, opts ServerRunOptions) error

func StartClient

func StartClient(ctx context.Context, key string, sock net.Conn) error

func StartSSHD

func StartSSHD(ctx context.Context, sshCmd string, mirrorSession bool, portCh chan<- int) error

func StartSignalServer

func StartSignalServer(ctx context.Context, port int) error

func StartTurnServer

func StartTurnServer(ctx context.Context, port int, addresses []string) error

func WithLogger

func WithLogger(ctx context.Context, l Logger) context.Context

Types

type BrokerRunOptions

type BrokerRunOptions struct {
	STUNPort      int
	STUNAddresses []string
	SignalPort    int
}

type ClientRunOptions

type ClientRunOptions struct {
	SessionKey string
	Stdin      io.Reader
	Stdout     io.Writer
	Stderr     io.Writer

	STUNServer   string
	SignalServer string
}

type ConnectInfo

type ConnectInfo struct {
	Source string `json:"source"`
	SDP    string `json:"sdp"`
}

ConnectInfo SDP by offer or answer

type DebugLogger

type DebugLogger struct {
	Logger
}

func (DebugLogger) Debugf

func (l DebugLogger) Debugf(format string, v ...any)

type Logger

type Logger interface {
	Printf(string, ...any)
	Errorf(string, ...any)
	Debugf(string, ...any)
}

func Log

func Log(ctx context.Context) Logger

type ServerRunOptions

type ServerRunOptions struct {
	LocalCommand  string
	MirrorCommand bool
	SessionKey    string

	STUNServer   string
	SignalServer string
}