Complete SSH Guide for Beginners: Generating, Naming and Mananing SSH Keys.

1. What is an SSH Key?

An SSH key is a pair of encrypted keys (public and private) used for secure remote login and authentication. Compared to passwords, SSH keys are more secure and easier to automate.

2. How to Generate an SSH Key?

Here’s how to generate the recommended key type ed25519, which works on most systems (Windows, macOS, Linux).

Open your terminal or command prompt and run:

ssh-keygen -t ed25519 -C "example@example.com" -f ~/.ssh/id_ed25519_example

Explanation:

-t ed25519: specifies the ed25519 key type
-C: adds a comment to help identify the key (e.g., email, name, or any text)
-f: sets the file name to avoid overwriting default keys

Follow the prompts and optionally set a passphrase. Two files will be created:

Private key: id_ed25519_example — keep this safe and never share
Public key: id_ed25519_example.pub — can be shared and added to servers or platforms like GitHub

3. How to View and Copy Your Public Key?

Your public key is in the .pub file. Use this command to display it:

cat ~/.ssh/id_ed25519_example.pub

Copy the entire output and paste it where your public key is needed, for example, in GitHub under SSH keys.

Note: There are also other ways to view the ssh keys

with scrolling less ~/.ssh/id_ed25519_example.pub
using text editor vim ~/.ssh/id_ed25519_example.pub or code ~/.ssh/id_ed25519_example.pub
or open the file manually
- Windows: C:\Users\<YourUsername>\.ssh\
- macOS/Linux: ~/.ssh/

4. Adding SSH Key to GitHub

Log in to your GitHub account.
Click your profile photo (top-right) → Settings.
In the left menu, select SSH and GPG keys.
Click the green New SSH key or Add SSH key button.
Enter a descriptive title (e.g., “Laptop key” or “Work PC”).
Paste your copied public key into the Key field.
Click Add SSH key to save.

Now you can interact with GitHub via SSH without typing your password.

5. How to Specify the SSH Key Filename?

When generating a key, you can use the -f option to set a custom filename, for example:

ssh-keygen -t ed25519 -C "example@example.com" -f ~/.ssh/id_ed25519_work

This creates id_ed25519_work and id_ed25519_work.pub, making it easier to manage multiple keys.

6. Managing Multiple SSH Keys and Accounts (e.g. GitHub & Servers)

If you have multiple GitHub accounts or different servers, manage them via the SSH config file ~/.ssh/config.

Suppose you have three keys:

~/.ssh/id_ed25519_personal — personal GitHub
~/.ssh/id_ed25519_work — work GitHub
~/.ssh/id_ed25519_server — remote server

Create or edit ~/.ssh/config and add:

# Personal GitHub account
Host github-personal
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_personal

# Work GitHub account
Host github-work
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_work

# Remote Server
Host my-server
  HostName your.server.com
  User yourusername
  IdentityFile ~/.ssh/id_ed25519_server

Usage examples:

For personal GitHub repo:
```
git@github-personal:username/repo.git
```
For work GitHub repo:
```
git@github-work:username/repo.git
```
SSH login to server:
```
ssh my-server
```

This lets you use different keys for different accounts and servers without confusion.

Summary

This guide covers all the essentials for working with SSH keys, including:

What SSH keys are and why they are better than passwords
How to generate secure ed25519 SSH keys with custom filenames
How to view and copy your public key for use on GitHub and servers
How to add your SSH public key to GitHub for passwordless access
How to manage multiple SSH keys and accounts using the SSH config file
Tips for naming keys and organizing multiple server connections

By following this guide, you will be able to confidently generate, name, and manage multiple SSH keys across different GitHub accounts and servers, improving your workflow security and convenience.

If you have any questions or want to share your experience, feel free to leave a comment below. Let’s learn together! ：）