Master SSH Authentication with Putty

Table of Contents:

1. Introduction
2. Logging into a Remote Server via SSH with Putty
3. Generating Public and Private Key Pair
4. Copying the Public Key onto the Server
5. Configuring Putty with the Key Pair
6. Achieving Passwordless Login
7. Conclusion
8. FAQ

Logging into a Remote Server via SSH with Putty

Logging into a remote server via SSH with Putty without a password provides a convenient and secure way to access your server. In this tutorial, we will walk through the process of setting up a passwordless login using Putty.

Introduction

SSH (Secure Shell) is a network protocol used to securely communicate with a remote server. Putty is a popular SSH client that allows users to establish secure connections to servers using various authentication methods, including password-based authentication and public-key authentication.

Step 1: Installing Putty

Before we can log into a remote server, we need to have Putty installed on our system. If you haven't already, you can download and install Putty from the official website at putty.org.

Step 2: Creating a Session

Once Putty is installed, we can proceed to create a session for our remote server. Open Putty and specify the IP address or hostname of the server you want to connect to. For example, if your server's IP address is 138.197.71.77, you would enter "root@138.197.71.77" as the hostname.

Step 3: Establishing a Connection

After entering the server details, click "Save" to save the session. Then, double click on the session to open the connection. If it's your first time connecting to the server, Putty will prompt you to confirm the connection. Click "Yes" to trust the connection. You will then be asked for the password to authenticate.

Step 4: Generating Public and Private Key Pair

To eliminate the need to enter a password for each login, we can generate a public and private key pair using PuttyGen. Download PuttyGen from putty.org and open the program. Click on the "Generate" button and follow the instructions to generate randomness by moving your mouse. Once the keys are generated, save the public and private keys to your computer.

Step 5: Copying the Public Key onto the Server

In order to enable passwordless login, we need to copy the public key onto the server. On the server, navigate to the ~/.ssh directory and open the authorized_keys file using a text editor such as Vim. Copy the public key generated by PuttyGen and paste it into the authorized_keys file. Save the file and exit the text editor.

Step 6: Configuring Putty with the Key Pair

Now, we need to configure Putty to use the key pair for authentication. Open Putty and load the session you created earlier. Under the SSH section, navigate to the authentication options. Specify the location of the private key file you saved earlier. Save the session to ensure the association between the session and the private key.

Step 7: Achieving Passwordless Login

With the configuration complete, you can now try logging into the remote server without entering a password. Double click on the session in Putty and it should authenticate using the public-private key pair, allowing you to access the server without a password prompt.

Conclusion

Setting up passwordless login using Putty provides a more convenient and secure way to access remote servers. By generating a public and private key pair and configuring Putty to use the keys, you can simplify the login process and enhance the security of your server.

FAQ

Q: Can I use passwordless login with any remote server? A: Yes, as long as the server supports SSH and allows public key authentication, you can set up passwordless login.

Q: Is passwordless login more secure than using a password? A: Yes, passwordless login using public key authentication is generally considered more secure since it eliminates the risk of password theft.

Q: Can I use the same public key for multiple servers? A: Yes, you can use the same public key for multiple servers, as long as you copy the public key onto each server's authorized_keys file.

Q: What happens if I lose my private key? A: If you lose your private key, you will no longer be able to access servers that have been configured to use that key. It is recommended to keep a backup of your private key in a secure location.

Q: Can I still use password-based authentication after setting up passwordless login? A: Yes, you can still use password-based authentication as a fallback option if needed. However, it is not recommended for security reasons.