Oct 14, 2019 Generating ed25519 SSH Key. I'm hoping to reinstall my MacBook Pro 15' 2017 with a fresh macOS Catalina sometime soon, and part of preparations is testing my install methods (hello, brew!) and configuration files migration. Today I decided to setup a new SSH keypair. What is ed25519? Ed25519 is a relatively new cryptography solution implementing.
To access your Compute instances using SSH, generate an SSH key pair, associate the public key with your instances, and use the private key to log in to the instances using SSH.
Caution:
Keep your SSH keys secure. Lay down policies to ensure that the keys aren’t lost or compromised when employees leave the organization or move to other departments. If you lose your private key, then you can’t access your instances. For business continuity, ensure that the SSH keys of at least two IT system administrators are added to your instances.
Topics
Generate an SSH Key Pair on UNIX and UNIX-Like Systems
Use the following procedure to generate an SSH key pair on UNIX and UNIX-like systems:
- Run the
ssh-keygen
command.You can use the-t
option to specify the type of key to create.For example, to create an RSA key, run:You can use the-b
option to specify the length (bit size) of the key, as shown in the following example: - The command prompts you to enter the path to the file in which you want to save the key.A default path and file name are suggested in parentheses. For example:
/home/
user_name
/.ssh/id_rsa
. To accept the default path and file name, press Enter. Otherwise, enter the required path and file name, and then press Enter. - The command prompts you to enter a passphrase.The passphrase is not mandatory if you want to log in to an instance created using an Oracle-provided image. However, it is recommended that you specify a passphrase to protect your private key against unauthorized use.Note:With some images provided on Oracle Marketplace, the use of a passphrase might be mandatory.
- When prompted, enter the passphrase again to confirm it.
The command generates an SSH key pair consisting of a public key and a private key, and saves them in the specified path. The file name of the public key is created automatically by appending
.pub
to the name of the private key file. For example, if the file name of the SSH private key is id_rsa
, the file name of the public key would be id_rsa.pub
. Make a note of the path and file names of the private and public keys. When you create an instance, you must specify the SSH public key value. When you log in to an instance, you must provide the path to the corresponding SSH private key and you must enter the passphrase when prompted.
Generate an SSH Key Pair on Windows
You can generate an SSH key pair on a Microsoft Windows machine by using an application such as PuTTY. See the tutorial, Creating SSH Keys for Use with Oracle Cloud Services.
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:
![Key Key](/uploads/1/2/6/0/126059811/308087295.jpg)
The system’s IP address is listed in the second entry:
Centos Generate Ssh Key Pair Linux
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:
Centos Generate Ssh Key Pair Authentication
Type yes and press Enter.
![How How](/uploads/1/2/6/0/126059811/164451314.jpg)
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.
Centos Ssh Setup
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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