The Secure Shell Protocol (SSH) is perhaps best known for establishing a secure connection between a client machine (laptop, phone, or desktop) and a remote server in your office, data center, or home network. It is a means of being. If you want to access the command line with a web hosting service or a headless Raspberry Pi, you will probably use SSH. SSH is available in some form on almost every operating system and is often integrated into the OS.
Most servers give you the option to connect to SSH via a password or a more secure SSH key. The SSH key method uses cryptographically generated public and private keys to create an encrypted connection between devices.
The public key is stored on the remote machine and the private key is stored on your machine. Two SSH keys are required to establish a secure connection. Keys can be used with passphrases to add another level of security, but they can also be used without passphrases, for example in automated processes.
In this how-to, you’ll learn how to create SSH keys in Windows Command Prompt/Linux Terminal using PuTTY, the most popular SSH client.
Preparing the remote server for SSH keys
Our remote machine can be in a data center operated by a web hosting service, in your office, or at your home. Linux servers, such as VPS and cloud hosting, typically run SSH by default with a password for secure login. If not, you will need to enable SSH from your VPS/cloud service’s control panel. If you’re using a home server, it may not be installed. If so, follow these steps before proceeding.
1. Open a terminal and check the SSH service running on your machine. Active: Active (running) is returned if the SSH service is running.
sudo service ssh status2. Open a terminal on the physical server and install the OpenSSH server. You have to sit at the machine to issue these commands.
sudo apt update
sudo apt install openssh-server3. Start the SSH service.
sudo service ssh start4. Create a hidden directory named .ssh in your home directory.
mkdir .ssh5. Press CTRL+D or type exit and press Enter to close the connection.
Use PuTTY to connect to a remote server using SSH keys
PuTTY is an application for creating and managing SSH and serial connections to devices. PuTTY comes with its own key generator application, and in this part of the method you will create a public key for your remote server and a private key for your trusted device.
1. Download and install PuTTY. Windows has its own command prompt that can be used with SSH, but PuTTY is the most accessible means of opening an SSH connection.
2. Search for puttygen and open the application.
3.[RSA]Click and set the bits to 4096.[生成]Click to create a key.
4. Move your mouse over a blank area of the dialog. Generate a random seed for the key.
5. Create a passphrase for your key. This is recommended for SSH keys used in interactive sessions.
6. Save the public key as id_rsa_putty.pub in a folder called .ssh.
7. Save the private key as id_rsa_putty.ppk. ppk file is Putty’s proprietary private key format.
8. Highlight the public key and copy the text.
Copy public key to remote server
1. Start PuTTY.
2. Enter the IP address or hostname of the remote server. When [開く]Click.
3. When prompted, enter your username and password for the remote server. Password is not displayed. This is a security feature to prevent “shoulder surfing”.
4. Create a new file named authorized_keys in the .ssh directory using the nano text editor.
5. Right-click and paste the public key (created with PuTTYGen). to an empty file. keep Press CTRL+X, then Y and Enter.
6. Log out of the SSH session Press CTRL+D.
7. Reopen PuTTY When Go to SSH >> Authentication.
8. Select your Putty private key (ppk). just created.
9.[セッション]Scroll to and enter the server hostname/IP address. When [開く]Click Start connection.
10. Enter your username and then enter the passphrase for the key. Press Enter to log in.
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You can now control your remote server using a Linux terminal working with a Linux filesystem. To close the connection, use CTRL+D or click X to close the window.
How to create an SSH key pair via Command Prompt/Terminal
Creating an SSH key pair from a command prompt/Linux terminal can be done with just one command and answering a few questions. Set up a public and private key on your client machine and copy the public key to the remote server. These instructions apply to Windows Command Prompt and Linux Terminal.
1. Press the Windows key to open Command Prompt and search for CMD. Press Enter to run.
2. Use the ssh-keygen command Create an SSH key using a 4096-bit RSA key type.
ssh-keygen -t rsa -b 4096
3. Press Enter when prompted to name the key.This will save the private and public keys in the named account’s .ssh directory. For example, the key was saved in C:\Users\lespo\.ssh. For Linux users, the key is stored in .ssh in home directory \home\user\.ssh.
Four. When prompted, Give the key a passphrase for an extra level of security. A passphrase is an additional security step for SSH keys used by real users (interactively). If you use her SSH connection in your automated script, no passphrase is required.
5. Change directory to your SSH key locationHere we assume that you are in the specified account. For example, C:\Users\lespo is ours. On Linux it will be /home/les/.ssh.
cd .ssh6. List the files in the directory. There should be id_rsa and id_rsa.pub.
Windows Command
dir
Linux Command
ls
Copy public key to remote server
The public key is stored on a remote server and interacts with the private key of trusted machines to form a secure connection. To get the public key to the server, you need to securely copy (scp) the file.
1. Securely copy id_rsa.pub to your home directory on the remote server using the scp command at a command prompt. You must know the remote computer’s IP address or host name. In this example, I copied the file to testuser@192.168.0.10:/home/testuser/.
scp id_rsa.pub user@hostname:/home/username2. SSH into the remote computer.
ssh user@hostname3. Make sure the id_rsa.pub file exists in your home directory.
ls *.pub4. Copy the contents of the file to a new file in the .ssh directory. Use the cat command to send the contents of the file to authorized_keys using a pipe (>>) that appends the data to the file.
cat id_rsa.pub >> .ssh/authorized_keys5. Press CTRL + D or type exit to close the SSH connection.
6. Reconnect to the remote computer via SSH.If you created a passphrase for your SSH key, you will be prompted to enter it.
Using SSH Keys on Another Machine
While it’s possible to reuse private SSH keys, it’s not the best security practice. If you use the key and lose your laptop, you will have to regenerate the key. Best practice is to generate a new key pair for each device you connect. Add your public key to the authrozied_keys file on your server. That said, reusing a private key on multiple devices is relatively easy.
PuTTY Private Key Reuse
PuTTY stores your private key as a PPK key. This file is all your machine needs to connect to a remote server using your public key.
1. Go to the .ssh folder and copy the PPK file to your USB stick. Keep this USB stick safe as anyone can use it to access your server.
2. Insert the USB stick into another computer.
3. Create a .ssh folder in your home directory. On Windows this is C:\Users\username\.ssh and /home/user/.ssh on Linux.
Four. Copy the PPK file to your .ssh directory.
Five. Log in as described in step 7 of Copying Your Public Key to a Remote Server.
Command Prompt/Terminal Private Key Reuse
1. Go to the .ssh folder and copy the private key file to your USB stick. Keep this USB stick safe as anyone can use it to access your server.
2. Insert the USB stick into another computer.
3. Create a .ssh folder in your home directory. On Windows this is C:\Users\username\.ssh and /home/user/.ssh on Linux.
Four. Copy the private key file to your .ssh directory.
Five. Start an SSH session to a remote computer. If you created a passphrase for your SSH key, you will be prompted to enter it.
ssh user@hostname
