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How to Generate SSH Keys (Linux)

SSH keys are a secure way of logging into your server without needing to use a password. This tutorial will guide you through the process of generating an SSH key using different types of encryption.

Step 1 - Open a terminal

Open your terminal. Most Linux distributions use Ctrl+Alt+T as a shortcut.

Step 2- Generate an SSH key

To generate an SSH key, use the ssh-keygen command. Here are the options you can use:

  • -t specifies the type of encryption. There is rsa, dsa, ecdsa, and ed25519.
  • -b specifies the number of bits in the key (only for certain key types).

I suggest using ed25519 (newer encryption) or rsa (older). Choose what you think will fit you.

ssh-keygen -t rsa -b 4096 -C "[email protected]"
ssh-keygen -t ed25519 -C "[email protected]"

Step 3 - Follow the prompts

After running one of the above commands, you will be prompted to specify the location to save the key.

Generating public/private ed25519 key pair.
Enter file in which to save the key (/home/your_username/.ssh/id_ed25519):

Press Enter to accept the default location, or specify a different path. Next, you will be prompted to enter a passphrase:

Enter passphrase (empty for no passphrase):
Enter same passphrase again:

A passphrase adds an extra layer of security. If you choose to set one, you will need to enter it whenever you use the key. Press Enter twice to skip setting a passphrase.

Step 4 - Verify Your keys

Your new SSH keys will be saved in the specified location. By default, the private key will be named id_ed25519 (or according to the encryption type you chose, e.g., id_rsa), and the public key will be named with a 

.pub
extension.

Example Session

Here's an example session generating an 

ed25519
key:

ssh-keygen -t ed25519 -C "[email protected]"
Generating public/private ed25519 key pair.
Enter file in which to save the key (/home/your_username/.ssh/id_ed25519):
Enter passphrase for "/home/your_username/.ssh/id_ed25519" (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/your_username/.ssh/id_ed25519
Your public key has been saved in /home/your_username/.ssh/id_ed25519.pub
The key fingerprint is:
SHA256:<REDACTED> [email protected]
The key's random art image is:
+--[ED25519 256]--+
|   E ..        o.|
|  . +.        oo.|
|   o  . .    . +=|
|     o . o    o=o|
|      + S o   . +|
|     . + @ = . . |
|      + O @ o . .|
|     . B * +   + |
|     o= o o ... .|
+----[SHA256]-----+

Conclusion

You have successfully generated an SSH key. You can now use this key to authenticate with servers that support SSH key-based authentication. Remember to keep your private key secure and never share it with anyone.

If you need help copying this SSH key to a server, I also have a small guide for that here: Generate SSH key (Linux).