cmc

ControlMaster Controller - Eases management of SSH ControlMaster connections

Overview

cmc makes SSH ControlMaster sessions easy. SSH ControlMaster sessions have the following benefits:

• When using a SSH Bastion, you will only be prompted for (two-factor) authentication once.
  • Hosts behind the SSH Bastion can be accessed "directly" by proxying through the SSH Bastion (see workflow_).
• Sessions to or through ControlMaster hosts do not need to create a new connection (SSH will be faster for most tasks)

Script Help

Usage:  cmc [ -c HOST | -x HOST ]
        cmc [ -l | -X ]
        cmc -h

ControlMaster Controller - Eases management of SSH ControlMaster connections

Options:
    -h      show this help message and exit
    -c HOST check HOST ControlMaster connection status (may be specified more
            than once)
    -d      print debug information
    -l      list all active ControlMaster connection sockets
    -x HOST exit ControlMaster session (may be specified more than once)
    -X      exit all ControlMaster connections with sockets

Notes:
    - Any unused sockets in ControlPath are removed with -l and -X

(output of cmc -h)

Install

1. Install Homebrew -- The missing package manager for macOS
2. Add the "tap":

   brew tap TimidRobot/tap

3. Install cmc:

   brew install cmc
   

Alternatively, since cmc is a bash script without esoteric dependencies, you can simply download it and ensure it is in your PATH.

If this utility is helpful for you, please star this project so that it can eventually be included in Homebrew proper. Thank you!

Documentation

ControlPersist

Prior to the addition of ControlPersist in OpenSSH 5.6, this utility was needed. However it still convenient to be able to quickly manage ControlMaster connections.

For more information on ControlPersist see ssh_config(5).

Workflow

See docs/workflow.

Annotated SSH Configuration

See docs/annotated_config.

Related

• any *nix Operating Systems (including Linux and macOS):
  • gacli: Mac CLI Google Authenticator client (ex. for use with SSH Bastions that utilize Google Authenticator or TOTP tokens)
  • solo-agent: Enable discrete SSH Agents to avoid leaking access across hosts
• macOS only
  • mac-ssh-confirm: Protect against SSH Agent Hijacking on macOS with the ability to confirm agent identities prior to each use

Requirements

• any *nix Operating System (including Linux and macOS) with:
  • core utilities (awk, find, grep, ps, and sed)
  • GNU Bourne-Again Shell 3.0 or later (bash)
  • OpenSSH 5.6 or later (ssh)
    • For OpenSSH versions between 4.0 and 5.6, try cmc 1.0.3

Development

Run ./testcmc TESTHOST prior to signing a new release.

Thank you:

• shellcheck - a static analysis tool for shell

License

• LICENSE (Expat/MIT License)