When facing authentication issues, which tool should you examine?

In the context of troubleshooting authentication issues on a Linux system, using pam_tally2 is highly relevant because this tool specifically helps monitor and manage user login attempts. It is primarily associated with the Pluggable Authentication Module (PAM) framework, and its main function is to keep track of failed authentication attempts. By using pam_tally2, an administrator can view the number of failed login attempts for users and reset those counts if necessary.

This functionality is crucial when diagnosing authentication issues because it allows you to identify whether a user account is being locked out due to multiple unsuccessful login attempts. With this information, administrators can take appropriate actions, such as unlocking the account or investigating the reason behind the failed attempts, which could include incorrect passwords or potential unauthorized access attempts.

While other tools mentioned can assist in various ways, they do not directly relate to the specific task of examining authentication failures. For instance, faillock provides similar capabilities but is considered a newer alternative; getent is used for querying user and group information from databases and does not specifically focus on authentication attempts; and ls -l serves to list files with detailed permissions but does not have any relation to user authentication. Thus, pam_tally2 is the most relevant tool to examine when faced with