Rospo

Rospo is a tool meant to create secure and reliable SSH tunnels. A single binary includes both client and server. It's meant to make SSH tunnels fun and understandable again

Table of Contents

1. Features
2. How to Install
3. Quick command line usage
4. Example Scenarios
   • Windows (WSL || PowerShell) reverse shell
   • Windows service to reverse tunnel Remote Desktop
   • Multiple complex tunnels

Features

• Easy to use (single binary client/server functionalities)
• Encrypted connections through ssh ( crypto/ssh package )
• Automatic connection monitoring to keep it always up
• Embedded sshd server
• Forward and reverse tunnels support
• JumpHosts support
• Command line options or human readable yaml config file
• Run as a Windows Service support
• Pty on Windows through conpty apis
• Sftp subsystem support server side
• File transfer support client side (get and put sftp subcommands)
• SOCKS5/SOCKS4 proxy server trough SSH
• DNS over SSH proxy

How to Install

Rospo actually full supports *nix oses and Windows 10+

macOS

Homebrew

Install rospo using Homebrew

brew install rospo

GNU/Linux

Binary Download

Platform	Architecture	URL
GNU/Linux	amd64	https://github.com/ferama/rospo/releases/latest/download/rospo-linux-amd64
	arm64	https://github.com/ferama/rospo/releases/latest/download/rospo-linux-arm64
	arm	https://github.com/ferama/rospo/releases/latest/download/rospo-linux-arm

Microsoft Windows

Binary Download

Platform	Architecture	URL
Microsoft Windows	amd64	https://github.com/ferama/rospo/releases/latest/download/rospo-windows-amd64.exe

Docker Container

You can use the docker ditribution where useful/needed

docker run ghcr.io/ferama/rospo --help

Quick command line usage

Rospo supports keys based auth and password auth. Keys based one is always the preferred, so it is better if identity, authorized_keys etc are always correctly setup.

Usage example:

Starts an embedded ssh server and reverse proxy the port (2222 by default) to remote_server

$ rospo revshell user@server:port

Forwards the local 5000 port to the remote 6000 on the remote_server

$ rospo tun forward -l :5000 -r :6000 user@server:port

Get more detailed help on each command runnig

$ rospo tun forward --help
$ rospo tun reverse --help
$ rospo sshd --help

For more complex use cases and more options, you can use a config file

$ rospo run config.yaml

Look at the config_template.yaml for all the available options.

Scenarios

Example scenario: Windows reverse shell

Why use an embedded sshd server you might ask me. Suppose you have a Windows WSL instance that you want to access remotely without complicated setups on firewalls and other hassles and annoyances. With rospo you can do it in ONE simple step:

$ rospo revshell remote_ssh_server

This command will run an embedded sshd server on your wsl instance and reverse proxy its port to the remote_ssh_server

The only assumption here is that you have access to remote_ssh_server. The command will open a socket (on port 2222 by default) into remote_ssh_server that you can use to log back to WSL using a standard ssh client with a command like:

$ ssh -p 2222 localhost

Or even better (why not!) with rospo you can reverse proxy a powershell. Using rospo for windows:

rospo.exe revshell remote_ssh_server

Example scenario: Windows service

Rospo support execution as a service on windows. This means that you can create a persistent tunnel that can be installed as a service and started automatically with the machine.

Let's do this with the Windows Remote Desktop service.

Create a rospo conf file like this:

sshclient:
  server: your-rospo-or-sshd-server-uri:2222
  identity: "c:\\absolute_path_to_your\\id_rsa"
  known_hosts: "C:\\absolute_path_to_your\\known_hosts"

tunnel:
  - remote: :3389
    local: :3389  # the windows remote desktop port
    forward: false

Launch a terminal (powershell) with Administrative rights. You can then perform the following actions:

# create the rospo service
sc.exe create rospo start= auto DisplayName= Rospo binpath= "C:\rospo.exe run C:\conf.yaml"

# start service
sc.exe start rospo

# query service status
sc.exe query rospo

# stop and delete the service
sc.exe stop rospo; sc.exe delete rospo

Example scenario: multiple complex tunnels

Rospo supports multiple tunnels on the same ssh connetion. To exploit the full power of rospo for more complex cases, you should/need to use a scenario config file. Let's define one. Create a file named config.yaml with the following contents

sshclient:
  server: myuser@remote_server_address
  identity: "~/.ssh/id_rsa"
  jump_hosts:
    - uri: anotheruser@jumphost_address
      identity: "~/.ssh/id_rsa"

tunnel:
  - remote: ":8000"
    local: ":8000"
    forward: yes
  - remote: ":9999"
    local: ":9999"
    forward: yes
  - remote: ":5000"
    local: ":5000"
    forward: no
    # use custom sshclient for this tunnel
    sshclient:
      server: myuser@another_server
      identity: "~/another_identity"

# starts a socks proxy ...
socksproxy:
  listen_address: :1080
  # ...using a dedicated client
  sshclient:
    server: localhost:9999

Launch rospo using the config file instead of the cli parameters:

$ rospo run config.yaml

What's happens here is that rospo will connect to remote_server_address through the jumphost_address server and will:

1. open a socket on the local machine listening on port 8000 that forwards all the traffic to the service listening on port 8000 on the remote_server_address machine
2. open a socket on the local machine listening on port 9999 that forwards all the traffic to the service listening on port 9999 on the remote_server_address machine
3. open a socket on the remote machine listening on port 5000 that forwards all the traffic from remote machine to a local service (on the local machine) listening on port 5000

But these are just an examples. Rospo can do a lot more.

Tunnels are fully secured using standard ssh mechanisms. Rospo will generate server identity file on first run and uses standard authorized_keys and user known_hosts files.

Rospo tunnel are monitored and kept up in the event of network issues.