ASSH - Augmented SSH

Automated, Self-Propagating Shell Enhancements for Every SSH Session

ASSH extends your local shell environment to remote SSH sessions, applying your local scripts and shell configs without the need for remote modifications.

Key Features

• Local Environment Replication
  Bring your .bashrc, and other local shell configs and scripts into remote sessions automatically. Enjoy the familiarity of your local setup, no matter which server you connect to.

• Zero Remote Changes
  Keep remote servers clean and secure. ASSH doesn’t modify remote configurations or scripts, making it lightweight and unobtrusive.

• Zero or Easy Setup
  ASSH is designed for simplicity. Configuration files are straightforward, allowing you to set up quickly and with minimal effort.

• 100% bash
  Written entirely in Bash for maximum portability across different systems and terminals.

Usage

Simple Setup

For a simple setup you could run this in your terminal:

git clone https://github.com/h2io/assh.git ~/.assh.d

Add this to your .bashrc:

export LH="${LH:-$(eval echo ${HOME}/.assh.d)}"
. "$LH/.asshrc" || echo "[assh] file not found"

Development Setup

For development you could add this instead:

export LH="${LH:-$(eval echo ${HOME}/.assh.d)}"
. "$LH/.asshrc" || echo "[assh] file not found"

export XD=1                         # develop flag
export LU="${LU:-$(eval echo ~)}"
XF=$(ls -d $LU/.assh*/.asshrc 2>/dev/null | sort | tail -n 1)
[[ -f $XF ]] && . "$XF" || true

This will load the last alpabetically ordered ~/.assh*/.asshrc.
You probably don't need more than one but it's sometimes usefull.
The develop flag now only refreshes ASSH version on PROMPT_COMMAND, for now.

Automatic Transfer to Server
When you connect to a server, the contents of ~/.assh* are automatically
copied, including the ASSH script, allowing you to use ASSH directly from
that server to other servers.

Using ASSH

ASSH behaves just like SSH but with added convenience and functionality:

• Standard Connection
  Connect to a server as you would with SSH:
  assh user@host

• Cascading Connections
  Once connected, you can use ASSH from the server to connect to another server:
  assh user@host2

• Quick Access to Commands
  Any executable scripts in the bin subdirectory are automatically available.
  I use filenames prefixed by , for easy lookup with ,<tab><tab>

  ,help
,cheat

• Reverse Port Forwarding with Copying
  Using assh -R host sets up reverse port forwarding, enabling you to copy
  files directly from the connected servers. You only use -R when you first
  start assh and the ,copy command will be available from all hosts.

  ,get <path>

• ControlMaster by Default
  ASSH enables ControlMaster by default for faster multi-server connections.
  Use -M0 to disable or -MX to close the ControlMaster socket.
  This ensures speed and control without using lengthy CLI parameters.

• sudo support
  You can keep using your ASSH config even after you sudo su.
  Just use ,su and all the configurations and scripts are available to you.

• ssh config templates
  .config.tpl is a template that includes .ssh/config and then allows you
  to customize the values you might need expanding the environment variables.
  The expanded template is saved to .config and used by the assh command.

  The config will not propagate on servers where the user you connect as is equal to $XDEBUG as defined in your environment (precursor to multi-tenant).

• No login messages
  By default, you get no motd messages. This behavior is controlled by the
  .hushlogin and .hushassh files. Removing these files will show you the
  default login messages or a customized version.

  This is very useful in an enterprise setting where you have various servers
  that give you information you can't really use for anything.

  The customized version you get by deleting .hushassh allows you to better see
  the server's status and to also get a unified message that you can customize
  as you see fit.

• Endless Customizations

You can customize the .sshrc for generic usage, add custom functionality
for each server you log in to, or for groups of servers.

~/.assh.d is just the main directory... all ~/.assh* directories get
loaded in alphabetical order and combined on the server you assh into. This
way, you can have group settings while also allowing for customization by
overwriting with custom functionality. This structure helps you maintain
group settings while keeping the flexibility to personalize your own,
ensuring that group configurations are still respected, but individual
preferences take precedence.

100% Compatibility, 100% Code is Bash

All code is Bash, so it can execute without problems on any Linux server. Here
is the list of external dependencies: bash, cat, eval, echo, find,
wc, kill, mktemp, printf, command, trap, read, unset, awk,
shuf, openssl, ssh, tar, rsync, envsubst. These are core external tools
and utilities widely present on Linux servers.

The code is not easy to understand completely, even if it’s only ~50 lines of
Bash, but it's not that difficult to review and ensure it does what it says.

• Extensibility
  These usage examples are just simplified use cases but there's a lot more
  that can be done, especially in the enterprise realm:
  • logging input/output of all the assh sessions
  • yubikey plugged into your laptop can be used on the server
  • plugin system for complex functionality
  • encryption is baked in and easily extended to other uses
  • group/team features, pastebin sharing
  • server health and notifications
  • intrusion detection
  • safe static binary execution from a trusted location
  • ... all with on-the-fly automatic setup and no modifications on the servers

ASSH extends SSH’s functionality without altering the familiar workflow,
streamlining multi-server connections and file operations being especially
useful for workflows with jump hosts, bastion servers, and multiple users
using the same accounts on the servers.

You get your personal configuration and scripts automatically even if it's the
first time you logged into that server. All the configurations are temporary
and get removed automatically when the connection breaks or you log out.