https://github.com/gliderlabs/sshfront

Programmable SSH frontend
https://github.com/gliderlabs/sshfront

Last synced: 8 days ago
JSON representation

Programmable SSH frontend

• Host: GitHub
• URL: https://github.com/gliderlabs/sshfront
• Owner: gliderlabs
• License: mit
• Created: 2014-06-02T00:30:20.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2023-12-15T20:43:47.000Z (11 months ago)
• Last Synced: 2024-08-01T22:51:01.699Z (3 months ago)
• Language: Go
• Homepage:
• Size: 41 KB
• Stars: 301
• Watchers: 14
• Forks: 28
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-ssh - sshfront - Programmable *SSH* frontend. (Apps / Servers)
• awesome-ssh - sshfront - Programmable *SSH* frontend. (Apps / Servers)

README

        
# sshfront

[![CircleCI](https://img.shields.io/circleci/project/gliderlabs/sshfront/release.svg)](https://circleci.com/gh/gliderlabs/sshfront)

[![IRC Channel](https://img.shields.io/badge/irc-%23gliderlabs-blue.svg)](https://kiwiirc.com/client/irc.freenode.net/#gliderlabs)

A lightweight SSH server frontend where authentication and connections

are controlled with command handlers / shell scripts.

## Using sshfront

    Usage: ./sshfront [options] 

    

      -a="": authentication hook. empty=allow all

      -d=false: debug mode

      -e=false: pass environment to handler

      -h="0.0.0.0": ip to listen on

      -k="~/.ssh/id_rsa": private host key path

      -p="22": port to listen on

#### handler $command...

`$command...` command line arguments specified to run by the SSH client

The handler is a command that's used to handle all SSH connections.

Output, stderr, and the exit code is returned to the client.

If the client provides stdin, that's passed to the handler.

If the authentication hook was specified, any output is parsed as environment variables and added to the handler environment.

`$USER` is always the SSH user used to connect and `$SSH_ORIGINAL_COMMAND` is the command specified from the client if not interactive.

#### auth-hook $user $key

 * `$user` argument is the name of the user being used to attempt the connection

 * `$key` argument is the public key data being provided for authentication

The auth hook is a command used for authenticating incoming SSH connections.

If it returns with exit status 0, the connection will be allowed, otherwise it will be denied.

The output of auth hook must be empty, or key-value pairs in the form `KEY=value` separated by newlines, which will be added to the environment of connection handler.

The auth hook is optional, but if not specified then all connections are allowed.

It is a good idea to always specify an auth hook.

See example/authcheck auth hook that checks that the pub key is authorized. Usage:

    sshfront -a example/authcheck

## Examples

**Many of these bypass authentication and may allow remote execution, *do not* run this in production.**

Echo server:

    server$ sshfront $(which echo)

    client$ ssh $SERVER "hello world"

    hello world

Echo host's environment to clients:

    server$ sshfront -e $(env)

    client$ ssh $SERVER

    USER=root

    HOME=/root

    LANG=en_US.UTF-8

    ...

Bash server:

    server$ sshfront $(which bash)

    client$ ssh $SERVER

    bash-4.3$ echo "this is a bash instance running on the server"

    this is a bash instance running on the server

SSH forwarding:

    server$ sshfront example/sshforward

    client$ ssh alice@$SERVER

    Forward ssh [email protected]...

    Welcome to another.server

## Sponsors

This project was made possible thanks to [Deis](http://deis.io) and [DigitalOcean](http://digitalocean.com).

## License

MIT