How to Use authorized_keys SSH: A Comprehensive Guide
In the world of remote access and secure server management, SSH (Secure Shell) is an essential tool. It allows users to securely log into a server and perform various administrative tasks. One of the key components of SSH is the use of authorized_keys, which ensures that only authenticated users can access the server. In this article, we will discuss how to use authorized_keys SSH to enhance the security of your server.
Firstly, it’s important to understand what authorized_keys are. Authorized_keys is a file that contains the public keys of users who are allowed to log in to a server via SSH. When a user attempts to connect to the server, the SSH client will send their public key to the server. The server then checks this key against the authorized_keys file to determine if the user is allowed to log in.
To start using authorized_keys SSH, follow these steps:
1. Generate SSH keys:
First, you need to generate a pair of SSH keys on your local machine. You can use the ssh-keygen command to do this. Run the following command in your terminal:
“`
ssh-keygen -t rsa -b 4096
“`
This command will generate a new RSA key with a 4096-bit key length. You will be prompted to enter a file to save the key. You can leave this as the default, or specify a different file. You will also be prompted to enter a passphrase to protect your key. It is recommended to set a passphrase for additional security.
2. Copy the public key to the server:
Once you have generated the SSH key pair, you need to copy the public key to the server. You can do this by using the ssh-copy-id command:
“`
ssh-copy-id [username]@[server_ip]
“`
Replace [username] with your username and [server_ip] with the IP address of your server. This command will automatically append the public key to the authorized_keys file on the server.
3. Configure SSH client:
To use the new SSH key for logging in, you need to configure your SSH client. Open the SSH configuration file on your local machine:
“`
nano ~/.ssh/config
“`
Add the following line to the file:
“`
Host [server_name]
HostName [server_ip]
User [username]
IdentityFile ~/.ssh/id_rsa
“`
Replace [server_name] with a name for your server, [server_ip] with the IP address, and [username] with your username. The IdentityFile line specifies the path to your private SSH key.
4. Test the connection:
Now, you can test the connection to the server using the following command:
“`
ssh [server_name]
“`
If everything is configured correctly, you should be prompted to enter your passphrase. Once you have entered the passphrase, you should be logged in to the server using your SSH key.
By following these steps, you can effectively use authorized_keys SSH to enhance the security of your server. Remember to regularly rotate your SSH keys and keep them secure to prevent unauthorized access.
