SSH Cheatsheet

Power user.

Overview

SSH fluency turns ad-hoc remote access into reproducible workflows. The patterns below are the small set every operator should have on muscle memory.

• Authenticated, encrypted shell. Public-key auth with end-to-end encryption. Passwords are not in the picture.
• Port forwarding. -L for local forward, -R for remote, -D for dynamic SOCKS. The three flags cover almost every tunnel use case.
• Config file. ~/.ssh/config captures per-host settings. The command line stays short and reproducible.
• Agent forwarding and multiplexing. -A forwards the agent for multi-hop access; ControlMaster reuses connections so repeat sessions skip the handshake.

The approach

Three habits separate a fluent SSH user from a tutorial-driven one: configuration lives in the config file, keys are modern, and multiplexing is on by default.

• Per-host config in ~/.ssh/config. Host, User, Port, IdentityFile. The command becomes ssh host, not a 60-character line.
• ssh-keygen -t ed25519. Modern algorithm, smaller keys, faster handshakes. RSA 2048 is legacy at this point.
• Local-forward and ProxyJump. ssh -L 5432:localhost:5432 host tunnels to internal services; ssh -J jumphost host chains through a bastion.
• ControlMaster auto. Connection multiplexing in the config. Repeat sessions skip the handshake; the operator notices the speed difference within a day.

Why this compounds

SSH fluency is high-leverage because the same patterns serve every remote-access task the operator runs. Each captured config saves seconds per use, compounded across thousands of sessions.

• Faster operations. Configured SSH removes friction from every remote task. The savings compound across the day.
• Stronger security. Key-based auth plus ProxyJump bastion patterns shrink the attack surface compared to direct password access.
• Reusable across the team. Sharing the config (with private bits redacted) gives every new engineer the same defaults.
• Year-one investment, year-two habit. The first config takes an afternoon. After a year, the patterns are reflexive.