How to Copy Public Key to authorized_keys in Linux
In the realm of Linux system administration, securely managing SSH keys is a crucial aspect for ensuring secure remote access to servers. One of the key tasks involves copying a public key to the authorized_keys file on the server. This article will guide you through the process of copying a public key to the authorized_keys file in Linux, step by step.
Understanding SSH Keys
SSH (Secure Shell) keys are cryptographic keys used to authenticate and authorize users for remote login and other secure network services over an unsecured network. SSH keys consist of a public key and a private key. The public key is stored on the server, while the private key is kept on the client machine. When a user attempts to connect to a server using SSH, the server uses the public key to verify the identity of the client.
Step-by-Step Guide to Copying Public Key to authorized_keys
1. Generate SSH Key Pair (if not already generated):
If you haven’t already generated an SSH key pair on your client machine, you can do so using the following command:
“`
ssh-keygen -t rsa -b 4096
“`
This command will generate an RSA key pair with a 4096-bit key size. You will be prompted to enter a file path for your private key and a passphrase for additional security.
2. Copy Public Key to Server:
To copy the public key to the server, use the `ssh-copy-id` command:
“`
ssh-copy-id [username]@[server-ip]
“`
Replace `[username]` with your Linux username and `[server-ip]` with the IP address or hostname of the server. This command will automatically append your public key to the authorized_keys file in the home directory of the specified user.
3. Manual Copy (Alternative Method):
If you prefer a manual approach, you can use the `cat` command to copy the public key from your client machine to the server. First, navigate to the directory where your public key is stored and copy the key:
“`
cat ~/.ssh/id_rsa.pub
“`
Then, log in to the server using SSH and append the key to the authorized_keys file:
“`
ssh [username]@[server-ip]
nano ~/.ssh/authorized_keys
“`
Paste the public key into the authorized_keys file and save the changes.
4. Test SSH Connection:
After copying the public key to the server, test the SSH connection to ensure it works correctly:
“`
ssh [username]@[server-ip]
“`
If the connection is successful, you have successfully copied the public key to the authorized_keys file.
Conclusion
Copying a public key to the authorized_keys file in Linux is a straightforward process that enhances the security of your remote connections. By following the steps outlined in this article, you can easily manage SSH keys and maintain secure access to your Linux servers.
