Canonical has access to the Microsoft signing PKCS#7 file (PCA 2010) (cdboot.pkcs) and its characteristics are being mimicked during key generation.Initial setup.
Introduction
Establishing an SSH (Secure Shell) connection is essential to log in and effectively manage a remote server. Encrypted keys are a set of access credentials used to establish a secure connection.
This guide will walk you how to generate SSH keys on Ubuntu 18.04. We will also cover setting up SSH key-based authentication to connect to a remote server without requiring a password.
- A server running Ubuntu 18.04
- A user account with sudo privileges
- Access to a terminal window / command line (Ctrl-Alt-T)
If you are already running an Ubuntu 18.04 server, you can skip this step. If you are configuring your server for the first time, you may not have SSH installed.
1. Start by installing the tasksel package:
The system will first ask for confirmation before proceeding:
2. Next, use tasksel to install the ssh-server:
3. Load the SSH server service, and set it to launch at boot:
On your client system – the one you’re using to connect to the server – you need to create a pair of key codes.
To generate a pair of SSH key codes, enter the commands:
This will create a hidden directory to store your SSH keys, and modify the permissions for that directory. The ssh-keygen command creates a 2048-bit RSA key pair.
For extra security, use RSA4096:
If you’ve already generated a key pair, this will prompt to overwrite them, and those old keys will not work anymore.
The system will ask you to create a passphrase as an added layer of security. Input a memorable passphrase, and press Enter.
This process creates two keys. One is a public key, which you can hand out to anyone – in this case, you’ll save it to the server. The other one is a private key, which you will need to keep secure. The secure private key ensures that you are the only person who can encrypt the data that is decrypted by the public key.
Step 2- Copy Public Key to the Ubuntu Server
First, get the IP address of the Ubuntu server you want to connect to.
In a terminal window, enter:
The system’s IP address is listed in the second entry:
On the client system, use the ssh-copy-id command to copy the identity information to the Ubuntu server:
Replace server_IP with the actual IP address of your server.
If this is the first time you’re connecting to the server, you may see a message that the authenticity of the host cannot be established:
Type yes and press Enter.
The system will check your client system for the id_rsa.pub key that was previously generated. Then it will prompt you to enter the password for the server user account. Type it in (the system won’t display the password), and press Enter.
The system will copy the contents of the ~/.ssh/id_rsa.pub from the client system into the ~/.ssh/authorized_keys directory of the server system.
The system should display:
If your system does not have the ssh-copy-id command, you can copy the key manually over the SSH.
Use the following command:
To log in to a remote server, input the command:
The system should not ask for a password as it is negotiating a secure connection using the SSH keys. If you used a security passphrase, you would be prompted to enter it. After you do so, you are logged in.
If this is the first time you’ve logged into the server, you may see a message similar to the one in part two. It will ask if you are sure you want to connect – type yes and press Enter.
Step 4- Disable Password Authentication
This step creates an added layer of security. If you’re the only person logging into the server, you can disable the password. The server will only accept a login with your private key to match the stored public key.
Edit the sshd_config file:
Search the file and find the PasswordAuthentication option.
Edit the file and change the value to no:
Save the file and exit, then restart the SSH service:
Verify that SSH is still working, before ending the session:
If everything works, you can close out and resume work normally.
By following the instructions in this tutorial, you have setup SSH-key-based authentication on an Ubuntu 18.04 server.
The connection is now highly secure as it uses a set of unique, encrypted SSH keys.
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SSH stands for “Secure Shell” and is an encrypted protocol used to log in and manage a remote server. SSH also supports various authentication mechanisms. SSH uses password-based authentication and public key-based authentication for a secure connection between a client and a server. SSH key-based authentication is more secure than password-based authentication because keys are very hard to guess or crack using currently available computing power.
In this tutorial, we will show you how to set up SSH key-based authentication on an Ubuntu 18.04 server.
Prerequisites
- Two fresh Ubuntu 18.04 VPS on the Atlantic.Net Cloud Platform.
- Root passwords configured on both servers.
Step 1 – Create an Atlantic.Net Cloud Server
First, log in to your Atlantic.Net Cloud Server. Create a new server, choosing Ubuntu 18.04 as the operating system with at least 2GB RAM. Connect to your Cloud Server via SSH and log in using the credentials highlighted at the top of the page.
Once you are logged into your Ubuntu 18.04 server, run the following command to update your base system with the latest available packages.
Step 2 – Generate the SSH Key on the Client Machine
First, log in to your client machine and generate a new SSH key pair by running the following command:
You will need to press Enter to accept the default file location and provide a passphrase to add an extra layer of security, as shown below:
The above command will generate a 2048-bit RSA key pair with a secure passphrase to prevent unauthorized users from logging in.
You can see the generated public and private keys with the following command:
You should see the following output:
At this point, you have public and private keys that you can use to authenticate with your Ubuntu server.
Step 3 – Copy the Public Key to the Ubuntu Server
Next, you will need to copy the public key from the client machine to your Ubuntu 18.04 server. You can copy the public key with ssh-copy-id utility as shown below:
You should see the following output:
Type “yes” and press ENTER to continue. You should see the following output:
Next, you will be prompted to enter the remote username and password. After the successful authentication, the content of the public key ~/.ssh/id_rsa.pub will be appended to the remote user ~/.ssh/authorized_keys file as shown below:
Step 4 – Disable SSH Password Authentication
Next, log in to your Ubuntu 18.04 server machine and disable SSH password-based authentication to add an extra layer of security to your server.
You can disable password-based authentication by editing the file /etc/ssh/sshd_config:
Find the following lines and change the value to “no”:
Save and close the file, then restart SSH service to apply the configuration:
Step 5 – Log in to the Server using SSH Keys
At this point, SSH key-based authentication is configured. Now it’s time to log in to the Ubuntu 18.04 server machine with the public key.
Ubuntu Generate Rsa Key Pair
You can login to your Ubuntu 18.04 server by simply running the following command:
Rsa-2048 Cracking
If you are logging in for the first time, you will be prompted as shown below:
2048 Bit Rsa Key
Type Yes and hit Enter key to continue. Next, you will be prompted to enter the passphrase for your private key as shown below:
Provide your private key passphrase and hit Enter to log in to your server.
Conclusion
Rsa 2048 Encryption
In the above tutorial, we learned how to set up an SSH key-based authentication with a passphrase on Ubuntu 18.04. The connection between your client machine and Ubuntu 18.04 server machine is now highly secure. You can also use the same key for another remote server. If you’re ready to get started with SSH key-based authentication, try VPS hosting with Atlantic.Net today.