SSH Key Setup Guide for Git and Remote Access

This guide helps you generate and use an SSH key for secure authentication with GitHub and remote servers.

What is an SSH Key, and Why Use It?

SSH (Secure Shell) keys are a secure way to authenticate without using a password. Like GPG keys, SSH uses a key pair:

• Your private key stays on your computer.
• Your public key is shared with remote services (like GitHub or a server).

Why Use SSH Keys?

• Secure logins without typing passwords
• Authenticate Git operations (clone, push, pull) securely
• Access remote servers with one command

GitHub and many servers prefer SSH over HTTPS for better security and ease of use.

1. Generate a New SSH Key

ssh-keygen -t ed25519 -C "[email protected]"

• Use ed25519 (modern, faster, more secure than RSA)
• When prompted, save to the default path: ~/.ssh/id_ed25519
• Optionally set a passphrase for extra protection

2. Add SSH Key to Agent

Start the agent and add your key:

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

If using a custom filename, replace with your actual key path.

3. Add SSH Key to GitHub

1. Copy the public key:

   cat ~/.ssh/id_ed25519.pub
   

2. Go to GitHub → Settings → SSH and GPG Keys

3. Click "New SSH Key", give it a title, and paste your public key

4. Test GitHub SSH Connection

ssh -T [email protected]

If successful, you'll see a message like:

Hi your-username! You've successfully authenticated.

5. Connect to Remote Server

To SSH into a server:

ssh user@host

Replace user with your server username and host with IP or domain name.

6. Copy SSH Key to Server

Quickly add your public key to a remote server:

ssh-copy-id user@host

Adds your key to the server’s ~/.ssh/authorized_keys file

7. Use SSH Config File for Convenience

Set up shortcuts and default identities.

Edit: ~/.ssh/config

Host github.com
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519

Host my-server
  HostName example.com
  User ubuntu
  IdentityFile ~/.ssh/id_ed25519

Now you can connect with:

ssh github.com
ssh my-server

SSH Cheatsheet