Homepage: https://github.com/epeli/subssh
Author: Esa-Matti Suuronen
Subssh is a small framework for building custom shells that work under a single OpenSSH-account. It separates users from each other with SSH public keys. This means that you don't have to create real accounts for Subssh-users.
Framework also helps you to manage the public keys. It does that by managing keys in the authorizes_keys-file. The file are managed in a friendly way so that you can also keep your own keys the file. Subssh makes sure that they remain untouched.
Subssh comes with bundled key management application which allows users to add and remove their keys. You can configure from ~/.subssh/config which Subssh applications are activated.
Subssh is a great tool if you want to build for example a restricted ssh-account for just rsync or rdiff-backup usage. For a working example see Revision Cask. It's a revision control management tool for which Subssh was originally written for.
For simple Subssh application example see the exampleapp.py file in the distribution.