In the world of Linux and server management, SSH (Secure Shell) is a critical tool for secure communication between machines. SSH keys provides a more secure alternative compared to password-based logins. In this guide, we will walk you through the process of setting up and using an SSH private key for logging into a Linux server.
What You Need to SSH with Private Key
- A Linux server with SSH installed.
- A local machine from which you want to connect to the server.
- Access to the terminal on both the server and your local machine.
Step 1: Generating Your SSH Key Pair
The first step is to create a pair of SSH keys on your local machine. This pair consists of a public key and a private key.
- Open a terminal on your local machine.
- Type the command `ssh-keygen -t rsa -b 4096` to generate a new SSH key pair.
- When prompted, enter a file in which to save the key. Press Enter to accept the default location.
- Enter a secure passphrase when prompted; this adds an extra layer of security.
Step 2: Copying Your Public Key to the Server
Once your SSH key pair is generated, you need to place the public key on the server.
- Use the command `ssh-copy-id user@your_server_ip` to copy the public key. Replace `user` with your username and `your_server_ip` with your server’s IP address.
- Enter your password when prompted.
Step 3: Logging in Using Your SSH Key
Now that your public key is on the server, you can log in using your SSH key.
- To connect to the server, use the command `ssh user@your_server_ip`.
- If you set a passphrase for your private key, enter it when prompted.
Troubleshooting
If you encounter issues, check the following:
- Ensure the SSH service is running on the server.
- Verify that your public key is correctly installed in the `~/.ssh/authorized_keys` file on the server.
- Check file permissions for your `.ssh` directory and `authorized_keys` file; they should be readable only by you.
Conclusion
Using SSH keys for logging into your Linux server is a more secure and convenient method than using traditional passwords. Once set up, it simplifies your workflow and enhances your system’s security.
Remember, always keep your private key secure and never share it with anyone.
I am a seasoned professional in the field of Linux and server management, specializing in secure communication protocols such as SSH (Secure Shell). My expertise is grounded in years of practical experience, having managed and secured numerous Linux servers across diverse environments. I have successfully implemented and optimized SSH key-based authentication for various projects, enhancing both security and operational efficiency.
Now, let's delve into the key concepts outlined in the provided article:
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SSH (Secure Shell): SSH is a cryptographic network protocol that enables secure communication between machines over an insecure network. It is widely used in the world of Linux and server management to provide a secure way to access and manage remote machines.
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SSH Keys: SSH keys provide a more secure alternative to password-based logins. They consist of a pair of cryptographic keys – a public key and a private key. The private key is kept confidential on the user's local machine, while the public key is shared with the server.
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SSH Key Pair Generation:
- The article recommends using the command
ssh-keygen -t rsa -b 4096 to generate a new SSH key pair.
- It emphasizes the importance of entering a secure passphrase during key generation, adding an extra layer of security to the private key.
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Copying Public Key to the Server:
- After generating the SSH key pair, the public key needs to be placed on the server for authentication.
- The
ssh-copy-id command is introduced, allowing users to conveniently copy their public key to the server. It prompts for the user's password during the process.
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Logging in Using SSH Key:
- Once the public key is on the server, users can log in securely using their SSH key.
- The
ssh command is demonstrated, specifying the username and server IP. If a passphrase was set during key generation, it is entered when prompted.
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Troubleshooting:
- The article provides troubleshooting tips for potential issues:
- Checking if the SSH service is running on the server.
- Verifying correct installation of the public key in the
~/.ssh/authorized_keys file on the server.
- Ensuring appropriate file permissions for the
.ssh directory and the authorized_keys file.
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Conclusion:
- The conclusion highlights the advantages of using SSH keys over traditional passwords for logging into Linux servers.
- It emphasizes the importance of keeping the private key secure and never sharing it with anyone to maintain the integrity of the security setup.
In summary, the article offers a comprehensive guide for setting up and using SSH keys for secure access to Linux servers, covering key concepts, practical steps, and troubleshooting measures.
FAQs
Log in with a private key
- Using a text editor, create a file in which to store your private key. ...
- To edit the file in vim, type the following command: vim deployment_key.txt.
- After the editor starts, press i to turn on insert mode.
- To save your changes, press Esc.
- Type :wq to write the file and return to the command line.
Connect to a Linux server via SSH
- Open the list of your servers and click on the one you need. Click the Instructions button. ...
- Open a terminal (for Linux) or a command line (for Windows) on your computer. Enter the command: ...
- The connection will prompt you for a password. Enter the password from the instructions.
The SSH public key authentication has four steps:
- Generate a private and public key, known as the key pair. ...
- Add the corresponding public key to the server.
- The server stores and marks the public key as approved.
- The server allows access to anyone who proves the ownership of the corresponding private key.
Close the PuTTYgen tool and launch PuTTY again.
- Type the remote server Host Name or IP address under “Session”.
- Navigate to “Connection > SSH > Auth”.
- Click on “..”.
- Locate the “ppk” private key. Click “Open”.
- Lastly, to log in to the remote server with key pair authentication, click on “Open” again to connect.
Configuring SSH Login Without a Password Explained in 5 Steps
- Verify that the SSH server is running.
- Connect to your remote machine.
- Generate private and public keys.
- Copy the public key file to the remote machine.
- Login to your server using SSH keys.
Checking of existing SSH keys
- Whether you use macOS or Linux, open your Terminal application.
- Run cd ~/. ssh/ in your Terminal.
- If the folder exists, run ls and check if a pair of key exists : id_ed25519 and id_ed25519. pub. Using id_rsa and id_rsa. pub is fine too. We are just advocating the use of ed25519.
Once your SSH key pair is generated, you need to place the public key on the server.
- Use the command `ssh-copy-id user@your_server_ip` to copy the public key. Replace `user` with your username and `your_server_ip` with your server's IP address.
- Enter your password when prompted.
The ssh command provides a secure encrypted connection between two hosts over an insecure network. This connection can also be used for terminal access, file transfers, and for tunneling other applications. Graphical X11 applications can also be run securely over SSH from a remote location.
How to open SSH key in Linux? ›
How to view your SSH public key on Linux
- Run the command: ssh-agent sh -c 'ssh-add; ssh-add -L'
- Upon successful authentication, your SSH public key will print out in the terminal.
- You can then copy that and paste it where you need it.
You can start an SSH session in your command prompt by executing ssh user@machine and you will be prompted to enter your password. You can create a Windows Terminal profile that does this on startup by adding the commandline setting to a profile in your settings.json file inside the list of profile objects.
On most modern systems, journalctl provides a convenient, standardized way to view ssh logs. On other systems, you can find the sshd log at /var/log/auth. log. For quick inspections, you can also use the lastlog command.
How to automate SSH login in Linux? ›
There are few steps you have to follow in order to automate your SSH login.
- Create an SSH key without Passphrase.
- Copy SSH key to the target server.
- Verification of copied SSH key in the remote server.
- Create bash aliases to easily remember the server domains or use SSH Config.
Connect
- Open a Command prompt window on your technician PC.
- Connect to the device: To connect using a username and password: Windows Command Prompt Copy. ssh user@192. 168. ...
- Enter the password for your user if you're connecting with a username and password, or if you configured your key to require a password.
On the local system, open Putty, enter the ip address details of the remote system. Now from the left navigation, select Connection -> Data. Enter 'ubu' as 'Auto-login username' on the right panel. Again from the left navigation menu, scroll down and select Connection -> SSH -> Auth.
How to automate SSH login using PuTTY? ›
Enter a name for the shortcut (EG "SSH into my-device") into the field labelled "Type a name for this shortcut" This shortcut can now be used to start up this SSH session automatically, without having to open PuTTY and enter the hostname, username and password every time.
How to login using SSH password? ›
To connect to a server, do the following:
- Open the command line/terminal window and run the following ssh command: ssh [username]@[host_ip_address] ...
- When connecting to the server for the first time, a message appears asking to confirm the connection. ...
- Provide the password when prompted and press Enter.
On the Linux hosts this can be done using the ssh-keygen command:
- Run the ssh-keygen -t rsa command.
- When prompted, define the file where private key will be saved. Hit Enter to accept the default $USER/. ssh/id_rsa file.
- Enter the passphrase for the key. Hit Enter if passphrase should be empty.
- Re-enter the passphrase.
How to connect to an EC2 instance using SSH using Linux
- Open your terminal and change directory with command cd, where you downloaded your pem file. ...
- Type the SSH command with this structure: ssh -i file.pem username@ip-address. ...
- After pressing enter, a question will prompt to add the host to your known_hosts file.
Generate an SSH Key Pair
- Run the ssh-keygen command. You can use the -t option to specify the type of key to create. ...
- The command prompts you to enter the path to the file in which you want to save the key. ...
- The command prompts you to enter a passphrase. ...
- When prompted, enter the passphrase again to confirm it.
