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SSH Controls

SSH Controls is a light-weight SSH public key distribution & management framework which:

  • uses a desired state model: SSH Controls pushes public keys from a key master server onto client host and applies them according to the central configuration.

  • uses SSH as transport mechanism: eat your own dog food. SSH Controls connects to client hosts through the secure path of SSH and using a public key that is under its own control.

  • shields public keys from owners/users on client systems: SSH Controls requires the standard sshd_config to be reconfigured with an alternate path for the AuthorizedKeysFile setting so that public keys are stored in common location which cannot be manipulated by the owners of the public keys. This allows for more administrative control and better security.

  • performs operations with least privileges: copy/distribute operations are performed with a low-privileged account. Only the actual key updates requires super-user privileges which need to be configured via SUDO.

  • supports a Master→Slave→Client model so that information can be propagated within more complex LAN set-ups.

  • uses a two-stage approach to activate public keys: copy (or distribute) and apply. Keys are first copied into a temporary location on each client hosts - the holding directory - and not applied automatically. Applying or activating keys on a client host is a separate operation which can be triggered either locally or remotely (from the SSH master)

  • can assign a single public key to multiple OS accounts: SSH Controls allows an user to log on under multiple accounts using the same key. Auditing of the connecting user and the target account is possible using fingerprinting.

  • allows the use of (nested) groups in the master configuration: users, keys and hosts can be grouped in the SSH master configuration files to allow a simplified configuration. Nesting of groups is allowed up to 5 levels deep.

  • allow the use of (nested) groups in the specification of the push targets. Either via the --targets command-line parameter or via the targets configuration file.

  • allows compromised public keys to be blacklisted: SSH Controls will deny the use of public keys that have been administrative blacklisted. Blacklisting happens on the SSH master and is applied to all client hosts.

  • can discover SSH host public keys to (re)create known_hosts file(s) for a large amount of hosts

  • supports md5 and sha512 fingerprint hashes (if the installed SSH version supports these hash types)

  • requires no client agent component and is stateless: SSH Controls performs operations by pushing keys or commands to client hosts. Update processes on the client hosts will only be started on-demand. If the SSH master is - for whatever reason - unavailable then active keys on a client host remain in place and logins are still possible.

  • is easy to configure and maintain (command-line based): the configuration is stored in a limited number of flat files and be easily updated. A very rudimentary syntax checking facility is also available to check the consistency of the most important (master) configuration files.


SSH Controls does NOT:

  • manage or distribute SSH private keys: SSH private keys should be controlled and managed (and safeguarded!) by the actual owners. Though one could consider SSH key pairs of generic accounts (such as application accounts) as an exception, SSH Controls currently does not support the management of private keys.


Download the software from following GitHub repository: https://github.com/patvdv/ssh_controls

Following topics provide more detail on the set-up and usage of SSH Controls:

  • Changelog:
    • The most interesting changes/fixes can be found in the Journal entries
    • Full changelog can be found on Github.




Backlinks: Projects Projects:SUDO Controls:Configuring a client host Projects:SUDO Controls:Requirements & components Projects:SUDO Controls:Setting up an SUDO master Journal:2018:Nov-03 - SSH+SUDO Controls updates Journal:2015:Oct-03 - SSH+SUDO Controls updates Journal:2015:Sep-27 - SSH+SUDO Controls updates Journal:2018:Aug-18 - HC+SSH Controls updates