Introduction
In this guide, we’ll focus on setting up SSH keys for a CentOS 8 server. SSH keys provide a straightforward, secure method of logging into your server and are recommended for all users. Step 1 — Creating the RSA Key Pair. The first step is to create a key pair on the client machine (usually your local computer): ssh-keygen. You’re looking for a pair of files named something like iddsa or idrsa and a matching file with a.pub extension. The.pub file is your public key, and the other file is the corresponding private key. If you don’t have these files (or you don’t even have a.ssh directory), you can create them by running a program called ssh-keygen, which is provided with the SSH package on Linux/macOS. Oct 29, 2012 It can create RSA keys for use by SSH protocol version 1 and RSA or DSA keys for use by SSH protocol version 2. He type of key to be generated is specified with the -t option. If invoked without any arguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 connections. $ restorecon -Rv /.ssh. Now when you login to the server you won't be prompted for a password (unless you entered a passphrase when you created your key pair). By default, ssh will first try to authenticate using keys. If no keys are found or authentication fails, then ssh will fall back to conventional password authentication.
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)
Centos Ssh Key Setup
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.
Centos 7 Generate Ssh Key
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:
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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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We’ll show you, how to set up SSH Keys on CentOS 7. SSH (Secure Socket Shell) is an open source, UNIX based, network protocol that provides users with a secure and encrypted way to login to remote computers, transfer files securely between the computers (SCP), command execution on remote servers, automate tasks between multiple servers on the network, and much more. SSH supports several authentication methods. In this tutorial we will configure SSH with public key authentication on CentOS 7 VPS, so instead of logging to your CentOS 7 VPS as usual using a username and password, you will be able to authenticate using a trusted SSH key which will increase the security of your server.
Prerequisites
– Two CentOS 7 servers (local and remote) with OpenSSH installed.
– SSH root access to the VPS which comes by default with all our VPS hosting plans.
Create SSH keypar on the local server
Advanced systemcare 12 key generator. Make sure that OpenSSH is installed on both servers. You can check if it is installed with the following command
In case it is not installed, you can easily install OpenSSH
First we will create SSH public and private key on the local server using the ssh-keygen tool provided by OpenSSH. You will be prompted to enter the location of the key. If there is no another key you can use the suggested location. You will be also prompted to enter a passphrase for your private key or leave it empty. Our recommendation is to set a strong passphrase. Run the following command to create a keypair with rsa algorithm:
Ssh On Centos
This will create 2048 bit keypair in the /root/.ssh directory on the local server, as shown above. Once the keypar is created on the local server, we have to copy the public key to the remote system that you want to access via SSH.
Centos Generate Ssh Host Keys On Computer
Copy the public key to the remote server
Next, we need to copy the newly created public key to our remote CentOS 7 VPS. We can easily do this using the ‘ssh-copy-id’ script.
You should get the following output:
Where IP_ADDRESS is the actual IP address of the remote server. The public key is successfully added and you should be able to login to the remote CentOS 7 VPS without entering a username and password. Run the following command
That’s all. If you closely followed the tutorial, you successfully configured SSH passwordless authentication between two CentOS servers. Additionally, you can strengthen the security of your server even more by disabling password authentication. To do this, open the SSH configuration file and set the PasswordAuthentication to no, as shown below
Save the file and restart the SSH server for the changes to take effect.
Of course you don’t have to set up SSH keys on CentOS 7, if you use one of our managed Ubuntu Hosting, in which case you can simply ask our expert Linux admins to configure SSH keys for you. They are available 24×7 and will take care of your request immediately.
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