Learning Secure Shell (SSH): Authentication and Security

Name: Learning Secure Shell (SSH): Authentication and Security
Author: Corey Thompson

Understand SSH security implementation through key pair authentication

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Course: On-Demand

Hello. My name is Corey Thompson. And in these lessons, you will learn how to generate public and private key pairs in both the Linux and Windows environments. Log in with your key pairs that you create and attempt a brute force attack on an SSH server. In this lesson, I will show you how to generate public and private key pairs on an ubuntu system. In SSH, it's the private public key relationship forms the foundation of secure authentication. The private key is a closely guarded secret that remains on the user's local machine and should never be shared. It is used for decrypting data that has been encrypted with the corresponding public key. On the other hand, the public key is a freely shareable key file that is stored on the remote server or system that the user intends to authenticate with. When the user attempts to establish an SSH connection, the client presents the public key to the server. The server then verifies the authenticity of the public key by checking against the corresponding private key stored on the client's machine. If the keys match, secure authentication is established and the connection is allowed. This asymmetric encryption scheme ensures secure communication and eliminates the need for passwords making SSH an essential tool for secure remote access. Now let's generate an SSH key pair, which consists of a public key and a private key for secure SSH connections. We're going to do this over on our ubuntu machine. Inside our terminal, we need to run the SSH Keygen Command. This is the command line utility used to generate and manage SSH key pairs. There are a few options we can run with this, beginning with the -t, followed by rsa, which will specify an rsa key pair. This generates both the public and private rsa keys using the default key length. When generating a key pair. SSH Keygen can offer different algorithms such as rsa, ED 25519, ECDSA, and a few others each with varying levels of security and performance characteristics. The user can also specify the key length, which affects the cryptographic strength of the generated keys. We can specify the output file if we would like with a -f and pass to the file. If we wanted to change the default size of the rsa key pair from 2048 to 4096, or even another value, we would add a - lowercase b followed by the value we would like. If we want to specify other algorithms, this is possible, but just ensure that if you choose advanced options such as eb25519, or others, it needs to be supported by both the client and the server. For now, we're going to stick with our rsa option and we're going to generate some test keys by changing the value from the default 2048 to 4096. So let's start with a clean command. We have our SSH-keygen. Now we need to specify that we want an rsa key. We don't need to specify -f because the keys will be saved in our default directory of SSH, and now was changed the value from 2048 to 4096. Go ahead and press enter. And you don't have to specify a key name if you don't want to here. But when you get to managing several keys, it helps keep track. So let's go ahead and make our test_key press enter. And here you have the option to add a passphrase. This passphrase acts as an additional layer of security that provides encryption for the private key file. Let's go ahead and enter a passphrase that we would like to be prompted. Enter the passphrase again. And now our keys should be generated. And as you can see in our .ssh folder, we have our tests_key and test_key.pub. Our public key is the one with the .pub extension. The public key is designed to be shared openly allowing remote servers to verify the authenticity of the client attempting to connect. It is derived from the corresponding private key using complex mathematical algorithms, but it does not contain any sensitive information or secret data. The other file named test_key is the private key that we generated. The private key must be kept strictly confidential and protected by a strong passphrase. This key is used for authentication on a user's end providing their identity to the remote server. The private key is generated alongside the public key, and while both keys are mathematically linked, it is computationally infeasible to deduce the private key from its public counterpart. Stay tuned for the next lesson where I will show you how to log in to the SSH server utilizing the SSH key pairs that we just created. Thanks for watching.

Beginner Provider : Corey Thompson 4 Lessons · 24m in Arabic, English

Course Description

In this course on Authentication and Security, you will learn how to utilize SSH key pairs. We will explore generating SSH key pairs, using keys for passwordless authentication, and using PuTTYGen inside a Windows environment. By the end of this course, you will be able to generate private and public keys, uses keys for authenticating against an OpenSSH server, create keys in a Windows environment, and hack into an SSH using brute force.

Learning how to generate SSH key pairs and proficiently utilize them for secure server logins is an essential skill. In these lessons, we will discuss and conduct SSH key generation to help you understand the cryptographic underpinnings that make this method highly secure. The course extends its focus to PuTTYGen, enabling users on Windows machines to seamlessly generate and manage SSH keys for authenticated server access. Additionally, you will explore the ethical considerations of network security by attempting to brute-force an SSH server using Nmap, gaining a hands-on understanding of potential vulnerabilities and the importance of robust security practices. By immersing themselves in these practical exercises, you will emerge with a heightened ability to safeguard systems, leverage encryption technologies, and bolster their competence in managing secure remote connections.

What You'll Learn

Generate public and private SSH key pairs and understand the cryptographic underpinnings that make this method secure
Use SSH keys for passwordless authentication against an OpenSSH server
Upload and utilize SSH keys for secure remote server logins
Create and manage SSH keys in a Windows environment using PuTTYGen and PuTTY key-based login
Securely manage SSH keys
Brute-force an SSH server using Nmap to understand potential vulnerabilities and ethical security considerations

Key Takeaways

SSH key pairs enable passwordless authentication and secure server logins, making them an essential skill for managing secure remote connections.
SSH key generation relies on cryptographic underpinnings that make this authentication method highly secure.
PuTTYGen lets users on Windows machines generate and manage SSH keys for authenticated server access.
Attempting to brute-force an SSH server with Nmap provides a hands-on understanding of potential vulnerabilities and the importance of robust security practices.
The course covers the ethical considerations of network security alongside practical, hands-on exercises.

Frequently Asked Questions

What will I be able to do after completing this course?

You will be able to generate private and public keys, use keys for authenticating against an OpenSSH server, create keys in a Windows environment, and hack into an SSH using brute force.

Does this course cover SSH key management on Windows?

Yes. The course focuses on PuTTYGen, enabling users on Windows machines to generate and manage SSH keys for authenticated server access, and includes a lesson on Windows PuTTY key-based login.

What lessons are included in this course?

The lessons are: Generating a Public/Private Key Pair; Uploading and Utilizing SSH Keys; Windows PuTTY Key-Based Login; and SSH Server Hacking.

What skills does this course teach?

The course covers brute force attacks, multi-factor authentication, PuTTY, and SSH keys.

How does the course approach SSH server hacking?

It explores the ethical considerations of network security by attempting to brute-force an SSH server using Nmap, giving you a hands-on understanding of potential vulnerabilities and the importance of robust security practices.