SSH Sync Manager

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Code: Download ZIP

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README

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Sn0wlinks SSH User Manager

Author: David Collins-Cubitt
Date: August 2023

Sn0wlinks SSH User Manager is a simple shell-based tool for synchronising SSH client configuration and propagating authorised SSH public keys across multiple remote hosts.
It is designed to make adding or removing users easy in medium to large server clusters without manual per-host key management.

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Purpose

• Deploy a standard ~/.ssh/config to a user account
• Push a centrally managed authorized_keys file to multiple servers
• Eliminate repetitive SSH key maintenance across hosts
• Quickly revoke or grant access by updating one file

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How It Works

1. Copies a predefined SSH client config into the local user’s ~/.ssh/
2. Iterates over a list of hosts
3. Replaces the remote user’s authorized_keys file on each host
4. Disables host key prompts to allow unattended execution

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File Overview

File	Description
config	SSH client configuration copied to ~/.ssh/config
hosts.sh	Plain-text list of SSH targets (one per line)
publickeys.sh	Combined public keys file to deploy as authorized_keys
script.sh	The main execution script

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Script Logic

Update Local SSH Configuration

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Overwrites the local SSH client configuration with the managed version.

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Push Authorized Keys to Remote Hosts

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• Reads each host from hosts.sh
• Copies publickeys.sh to the remote host
• Replaces ~/.ssh/authorized_keys
• Suppresses host key verification prompts for automation

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Completion Confirmation

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Requirements

• OpenSSH client (ssh, scp)
• SSH access to all target hosts
• Existing user accounts on remote systems
• Write access to ~/.ssh/authorized_keys

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Security Notes ⚠️

• *This script overwrites authorized_keys*
  • Any existing unmanaged keys will be removed
• StrictHostKeyChecking=no reduces security
  • Use only on trusted networks
• Ensure correct file permissions on targets:

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Typical Use Cases

• Managing SSH access across compute clusters
• Lab or staging environments
• Small infrastructure without centralized IAM
• Rapid access revocation by deleting keys centrally

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Limitations

• No validation of remote permissions
• No rollback or backup
• No per-host conditional logic
• Not suitable for untrusted or public networks