Authentication

Authentication

The authentication section with articles about users, passwords, logins, and more. Learn how to implement security measures to improve Linux authentication.

How to add a SSH key to the SSH agent

Learn how to load and use your SSH key together with a SSH agent. This frequently asked question will explain the usage of ssh-add and ssh-agent.

What is SSH agent forwarding?

The agent forwarding feature in SSH allows using your local SSH agent to be reached through an existing SSH connection. Learn when and how to use it.

How to start the SSH agent?

The OpenSSH agent helps with authentication by making SSH keys available. Learn how to start the SSH agent when it is not running on your Linux system.

What is the purpose of the SSH agent?

The SSH agent is a helper utility to temporarily store private keys when using public key authentication. Learn more about how this helps during daily tasks.

How to disable the usage of the SSH agent

The SSH agent can be used to simplify authentication. As that is not always preferred behavior, we can disable the SSH agent when authenticating.

How to disable the SSH host key check?

OpenSSH performs a host authenticity check when connecting to a system. Learn how to disable the check with the SSH option StrictHostKeyChecking.

How to terminate a SSH connection that does not respond to CTRL+C

Learn about SSH escape sequences and how they can help with terminating a SSH connection that does not respond to CTRL+C.

How to remove the passphrase from a SSH key

While protecting SSH keys is typically advised, it is not always feasible in automated processes. Learn how to remove the password or passphrase from a SSH key.

How to see the available SSH keys in the OpenSSH authentication agent

The SSH agent can load stored SSH keys into memory for authentication purposes. Use the ss-add command to show the available SSH keys that are loaded.

How to test if an account has a password set?

Want to determine if a Linux account has a password set or its related properties? Here are few methods to check this and the steps to perform.

Locking users after X failed login attempts with pam_tally2

The pam_tally2 module allows system administrators to block accounts after a number of incorrect login attempts. This guide explains how to use it with SSH.

Configure the minimum password length on Linux systems

One of the options to improve password security is by setting a minimum password length. This article explains how to configure and test this security step.

Find and Disable Insecure Services on Linux

Learn how to find and disable those services on Linux that are nowadays are considered to be unsafe or known for the weak security.

Granting temporary access to your servers (using signed SSH keys)

SSH has the capabilities to give a colleague or vendor temporary access to your systems. Learn how to install and configure the related SSH settings.