For developers and system administrators, SSH remains the unshakeable backbone of remote server management. Yet many still manually type full ssh user@host -p port commands, unaware of the efficiency and security optimizations hiding in plain sight within their ~/.ssh/config file. Let's demystify these professional-grade SSH techniques.

The Config File: Your SSH Shortcut Engine

Your OpenSSH client configuration (~/.ssh/config) acts as a command-line shortcut generator. A well-structured config replaces verbose connection strings with simple aliases:

Host jupiter
    Hostname 192.168.1.10
    User chuck
    Port 21098
    ServerAliveInterval 60
    ServerAliveCountMax 3

Host mercury
    Hostname 192.168.1.30
    User chuck
    Port 22212

This configuration reduces ssh [email protected] -p 21098 (31 keystrokes) to ssh jupiter (11 keystrokes). The ServerAliveInterval and ServerAliveCountMax settings prevent stale connections—critical for unstable networks.

Protocol Clarification: SFTP ≠ FTPS

A common point of confusion clarified in the source material:
- SFTP: SSH File Transfer Protocol (part of OpenSSH), provides encrypted file transfers and filesystem operations (ls, mv, etc.)
- FTPS: FTP over SSL/TLS, a secured version of legacy FTP
- FTP: Legacy plaintext protocol (avoid)

SFTP inherits your SSH config settings, enabling sftp jupiter just like SSH connections.

Passwordless Authentication: Security Through Keys

Eliminate password prompts and strengthen security with SSH keys:

  1. Generate Keys: 

    ssh-keygen -t rsa -b 4096 -C "[email protected]"

    (Accept defaults, skip passphrase for automation)

  2. Deploy Public Key: 

    ssh-copy-id user@host

  3. Connect Instantly: 

    ssh jupiter  # No password required

Security Implications

While changing the default SSH port (22) deters automated attacks, key-based authentication provides far stronger protection. Remember:
- Passphrase tradeoff: Unencrypted keys enable automation but risk exposure
- Port obscurity ≠ security: Always combine with key auth and firewall rules

The Silent Efficiency Multiplier

These techniques compound time savings: simplified commands, eliminated passwords, and automated scripts. For professionals managing dozens of systems, mastering the SSH config transforms a routine task into an optimized workflow.

Source: chuck.is/ssh/