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Asked: 2024-09-23T17:46:30+05:30 In:

What is the process for including SSH keys in the authorized_keys file on an Ubuntu system?

I’ve been trying to set up SSH access on my Ubuntu server, and I’m running into a bit of a wall. I know that SSH keys are supposed to make the whole process more secure and convenient, but I’m stuck on how to actually include these keys in the `authorized_keys` file.

So, here’s the deal: I’ve generated an SSH key pair on my local machine using `ssh-keygen`, and I have the public key saved. I’m wondering how to get this public key onto my Ubuntu server so that it’s recognized when I try to connect. I’ve read some stuff about the `authorized_keys` file, but I’m not totally clear on the exact steps involved.

First of all, do I need to create the `~/.ssh` directory on the server if it doesn’t already exist? I think I remember reading something about that. And when I transfer my public key, do I just need to copy-paste it into that file, or is there a specific command I should use?

I’ve seen a few different methods mentioned, like using `ssh-copy-id` or manually copying and pasting the key. What’s the best practice here? Are there any pitfalls I should avoid while doing this? I can’t afford to mess up the access because this is for a project I’m working on, and I need to ensure everything is set up correctly.

Also, once I add the key to the `authorized_keys` file, do I need to change any file permissions? I remember hearing something about making sure the `.ssh` folder and the `authorized_keys` file have the right permissions to prevent any access issues.

Any help from people who have gone through this process would be super appreciated. I just want to make sure I’m doing it the right way before I lock myself out of my server! Thanks!

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    2 Answers






    1. Setting up SSH Access on Ubuntu Server

      Setting up SSH Access on Ubuntu Server

      It sounds like you’re on the right track! Here’s a simple way to add your SSH public key to your Ubuntu server so you can connect without password prompts.

      1. Create the `~/.ssh` Directory

      First, you’ll want to check if the `~/.ssh` directory exists on your server. If not, create it by connecting to your server (using your current method) and running:

      mkdir -p ~/.ssh

      2. Add Your Public Key to `authorized_keys`

      You can add your public key in a couple of ways:

      • Using `ssh-copy-id`: This is the easiest and safest way! Run the following command from your local machine:
        • ssh-copy-id username@your-server-ip

        Replace username and your-server-ip with your actual username and server IP address. This will automatically append your public key to the ~/.ssh/authorized_keys file on the server, creating the file if it doesn’t exist.

      • Manually Copying and Pasting: If you prefer to do it manually, you can copy your public key (usually found at ~/.ssh/id_rsa.pub on your local machine) and paste it into the ~/.ssh/authorized_keys file on the server:
        • cat ~/.ssh/id_rsa.pub | ssh username@your-server-ip 'cat >> ~/.ssh/authorized_keys'

      3. Check File Permissions

      After you’ve added your key, it’s important to set the correct permissions to avoid access issues:

      chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

      This ensures that only your user can access these files, which is crucial for security.

      Quick Tips

      • Make sure to double-check the file permissions after adding the keys.
      • Avoid using the root account directly for SSH; create a normal user with sudo privileges instead.
      • If you ever find yourself locked out, you can still access your server using other methods, usually through a console or recovery mode provided by your hosting service.

      With all that said, once you’ve added your key and set the permissions, you should be able to SSH into your server without needing a password. Good luck with your project!


    2. To set up SSH access on your Ubuntu server using your public key, you’ll first want to ensure that the `~/.ssh` directory exists for the user you wish to log in as. If it does not exist, you can create it by logging into your server and running the command mkdir -p ~/.ssh. This directory should be set with the correct permissions to enhance security: you can achieve this by executing chmod 700 ~/.ssh. Once the directory is created, you can either copy the public key into the `authorized_keys` file manually or use the ssh-copy-id command, which is the recommended method for convenience and security. To use ssh-copy-id, simply run ssh-copy-id username@server_address and it will handle the copying of the key for you, adding it to the `authorized_keys` file automatically.

      Once your public key is in the `~/.ssh/authorized_keys` file, it’s crucial to set the correct file permissions to avoid any access issues. The authorized_keys file should be set to 600 permissions by running chmod 600 ~/.ssh/authorized_keys. This allows only the user to read and write the file, ensuring that it’s secure. As a precaution, review your SSH configuration in /etc/ssh/sshd_config to make sure PubkeyAuthentication is set to yes, and restart the SSH service if necessary. Avoid mixing methods; stick to either ssh-copy-id or manually copying the key to reduce complexity and potential mistakes. Following these best practices should help you maintain a secure connection without locking yourself out of the server.

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