How do you use the generated SSH key?

That's an excellent question, and it's key to understanding how SSH authentication works! I'm Labby, and I can explain.

You've just generated an SSH key pair:

A private key (~/.ssh/id_rsa_lab_ssh)
A public key (~/.ssh/id_rsa_lab_ssh.pub)

Using these keys for SSH authentication involves a simple, yet powerful, principle:

Your private key stays securely on your local machine (the client). It's like a very secure secret password that only you have. Crucially, you should never share your private key with anyone.
Your public key is copied to the remote server you want to connect to. You can share your public key freely; it contains no sensitive information that could compromise your security if someone else sees it.

Here's the general workflow:

Step 1: Put the public key on the server.
You (the client) will upload or append the contents of your public key (id_rsa_lab_ssh.pub) to a special file on the remote server (sshuser@your_server_ip in our case). This file is typically located at ~/.ssh/authorized_keys within the server user's home directory. This tells the server: "Hey, if anyone tries to connect claiming to be sshuser and they can prove they have the matching private key for this public key, let them in!"
Step 2: Connect from your client machine.
When you try to SSH from your machine (client) to the server (sshuser@your_server_ip), your SSH client will:
a. Identify the private key: It looks for your private key (in our case, ~/.ssh/id_rsa_lab_ssh).
b. Prove identity to the server: It then sends a challenge to the server, cryptographically proving that it possesses the private key corresponding to the public key stored in the server's authorized_keys file.
c. Server grants access: If the cryptographic challenge is successful (i.e., the private and public keys match), the server trusts that you are who you claim to be and grants you access without needing a password.

In the context of this lab:

In the next steps of this lab, you will perform exactly this process:

You will copy your public key (~/.ssh/id_rsa_lab_ssh.pub) into the authorized_keys file for the sshuser on your Docker SSH server.
Then, you will initiate an SSH connection from your local machine to the Docker SSH server using your private key. Your SSH client will automatically use your private key to authenticate with the server.

This method is generally more secure and convenient than using passwords alone, especially for automated scripts or if you need to manage access to many servers.

Does that explanation clarify how these keys are used? Let me know if anything is unclear!