Linux SSH Key Management

See this article for an update based on obsolete SHA-1 RSA key usage: Ubuntu 22.04 SSH the RSA key isn't working since upgrading from 20.04

NOTE: We currently have two tutorials for this, that need to be consolidated into one. So, maybe this alternate tutorial fills your use-case: How to Setup SSH Key Authentication to Linux

Step 1 - Key Creation

Follow this page for creating keys in Linux: Creating SSH Keys in Linux

Or, Follow this page for creating keys in Windows: Creating SSH Keys in Windows

After following one of the above tutorials, you should have a public and private key that you can use to authenticate.

The next step is to place the public key on your server so that you can use SSH-key-based authentication to log in.

Step 2 — Copying the Public Key to a Linux Server

There’s a couple ways to add an SSH public key to a remote host:

• Using SSH-Copy-ID

• Using CAT

• Manually Copying

Using SSH-Copy-ID

The quickest way to copy your public key to the Ubuntu host is to use a utility called ssh-copy-id. Due to its simplicity, this method is highly recommended if available.

See this page for how to use it: Adding SSH Keys with ssh-copy-id

Using CAT

If you do not have ssh-copy-id available, but you have password-based SSH access to an account on your server, you can upload your keys using a conventional SSH method.

Here’s a method for uploading an SSH key with cat: Adding SSH Keys with CAT

Manually Copying

If you don’t have SSH access to the remote host, you will need to directly paste in a user’s SSH public key.

See this page for how to manually add SSH keys to a Linux host: Linux: Manually Installing SSH Keys

Step 3 — Authenticating to Your Ubuntu Server Using SSH Keys

If you have successfully completed one of the procedures above, you should be able to log into the remote host without providing the remote account’s password.

See this page for how to: Authenticating to Linux Server with SSH Keys

If key-based authentication was successful, continue on to learn how to further secure your system by disabling password authentication.

Step 4 — Disabling Password Authentication on Your Server

Once you have confirmed that you can access the VM, with SSH key authentication, follow this page to disable password authentication: Linux: Disabling Password Authentication

Conclusion

You should now have SSH-key-based authentication configured on your server, allowing you to sign in without providing an account password.

If you’d like to learn more about working with SSH, take a look at our SSH Essentials Guide.