How To Setup SSH Key On Linux Server?

Author: Eman Feb 28, 2023 799 0

Secure Shell (SSH) is a cryptographic network protocol that allows you to securely connect to a remote server or computer. SSH uses a pair of keys, a public key, and a private key, to authenticate users and establish a secure connection between two systems. Using SSH keys is a more secure and convenient way to access remote servers than using passwords. In this article, we will guide you through the process of how to setup and use SSH keys on a Linux server.

What is SSH?

Secure Shell, commonly abbreviated as SSH, is a cryptographic network protocol that allows secure communication between two computers over an insecure network. It was created as a replacement for Telnet and other insecure remote shell protocols that transmitted data in plaintext, making them vulnerable to interception and manipulation by hackers.

SSH is widely used in the administration of remote servers and other networked devices, as well as for secure file transfers and other applications that require secure network communication. It operates on the transport layer of the OSI model and uses a combination of public-key and symmetric-key encryption to provide confidentiality, integrity, and authentication.

The SSH protocol consists of two components: the SSH server and the SSH client. The server runs on the remote machine, while the client runs on the local machine. When a client initiates a connection to a server, they exchange cryptographic keys to establish a secure communication channel. Once the channel is established, the client can execute commands on the server, transfer files, or perform other operations securely.

What are SSH authentication methods and how they work?

SSH (Secure Shell) is a protocol used to access remote systems securely over an unsecured network. SSH authentication methods refer to the ways in which a user or system proves its identity when connecting to a remote system via SSH. we will explore the different SSH authentication methods and how they work.

1. Password authentication:

Password authentication is the most common SSH authentication method. It involves the user providing a username and password to the remote system when prompted. This method is vulnerable to brute-force attacks, where an attacker repeatedly tries different passwords until they find the correct one.

To mitigate this vulnerability, SSH allows administrators to disable password authentication and use other authentication methods instead.

2. Public Key authentication:

Public key authentication, also known as asymmetric key authentication, is a more secure authentication method than password authentication. In this method, the user generates a pair of keys: a public key and a private key. The user keeps the private key on their local system, while the public key is copied to the remote system.

When the user connects to the remote system, the SSH client sends the user's public key to the remote system. The remote system uses the public key to encrypt a message and sends it back to the user's SSH client. The user's SSH client decrypts the message using the private key and sends it back to the remote system. If the message matches the expected response, the user is authenticated.

Public key authentication is more secure than password authentication because the private key is not transmitted over the network, and it is virtually impossible to brute-force the private key.

3. Host-based authentication:

Host-based authentication is an SSH authentication method that authenticates a user based on the hostname of the remote system. This method is typically used in organizations where all the systems are managed centrally, and users are authenticated based on their role in the organization.

In host-based authentication, the user's identity is verified based on the hostname of the remote system. If the user's identity is valid, they are granted access to the system.

4. Kerberos authentication:

Kerberos authentication is an SSH authentication method that uses a third-party authentication server to verify a user's identity. In this method, the user sends their credentials to the authentication server, which verifies the credentials and sends a ticket back to the user.

The user sends the ticket to the remote system, which then validates the ticket with the authentication server. If the ticket is valid, the user is authenticated. Kerberos authentication is more secure than password authentication because it uses a third-party authentication server, which provides an additional layer of security.