An introduction to Docker for operating system-level virtualization with minimal overhead compared to hypervisors. Covers creating containers for application components like databases and web servers, security benefits of isolation, and discovering Dokku for PaaS-like deployment similar to Heroku.

A guide for managing multiple SSH private keys on a single system, useful for accessing different servers or working with Amazon EC2. Shows how to configure the .ssh/config file to specify different identity files, hostnames, users, and ports for each server, enabling easy SSH access by hostname alone.

A guide to protecting SSH servers on Linux from brute force attacks. Covers disabling root login, changing SSH ports, using iptables rate limiting rules to temporarily block aggressive IPs, and installing DenyHosts for permanent blocking with optional synchronization to a community blocklist.

A practical guide to encrypting and decrypting files using OpenSSL with AES-256-CBC encryption. Covers basic file encryption/decryption, piping data through OpenSSL for processing, and using the same algorithms for consistent encryption and decryption operations.

A quick tip for preventing SSH connections from dropping due to inactivity by editing the ssh_config file to send keep-alive packets every 30 seconds, ensuring stable connections on networks with aggressive timeout settings.

An introduction to SSH tunneling techniques for secure data transmission. Covers dynamic port forwarding for web browsing and IM clients, local port forwarding for RDP/VNC access, and reverse tunneling for accessing systems behind firewalls. Includes examples and automation scripts, plus instructions for PuTTY users on Windows.

A comprehensive guide to creating and using SSH keys for secure passwordless authentication. Covers key generation, understanding public-key cryptography, key distribution using authorized_keys, and using PuTTY on Windows to enable secure login and automate file transfers without passwords.