SSH for Mere Mortals

SSH (Secure Shell) is the encrypted pipe between your computer and every server you'll ever touch. This guide teaches you to use it confidently: connecting, keys, the config file, jump hosts, tunnels, moving files, and fixing it when it breaks.

No CS degree required. Ideas first, then real commands against a real OpenSSH.

What this guide covers

What SSH is — the encrypted-pipe idea, and the three questions every connection answers
Your first connection — ssh user@host, host keys, and the first-run leap of faith
Passwords vs keys — why keys win, and the padlock mental model
Your first key — ssh-keygen, ssh-copy-id, and the permission rules
The SSH config file — nicknames, ports, and per-host settings, verified with ssh -G
Jump hosts — reaching private networks through one command (ProxyJump)
The SSH agent — type your passphrase once; plus the honest caveats on forwarding
Connection multiplexing — pay the handshake once
Tunneling — -L, -R, and -D, each with a concrete use case
Moving files — scp, sftp, and rsync over SSH
Server-side basics — the sane sshd_config, validated before restart (deeper hardening lives in the Cybersecurity guide)
Troubleshooting — symptom → fix, six ways

What it doesn't cover

SSH certificates (the enterprise way to manage keys), sshd advanced auth (Kerberos, 2FA modules), and running public-facing SSH at scale — the Cybersecurity guide covers the hardening side. This guide is about using SSH well.

How to use this guide

Every command was checked against the real OpenSSH 9.6p1 client before shipping — flags verified, config examples parsed with ssh -G, keys generated for real, and a loopback server used for the connection chapters. Check: blocks show verified output. Anything labeled illustrative says so.

Chapters

Written to the nine-point writing standard shared by every guide in this series.