Linux Security and Hardening, The Practical Security Guide

Explore why Linux is considered relatively secure and how the superuser differs from other users, then examine open source implications, encryption, multi-factor authentication, software management, and least privilege.

Adopt practical security guidelines and principles for Linux, minimize installed software, isolate services, enforce least privilege, enable multi-factor authentication, log activity, and encrypt data in transit and at rest.

Learn to secure Linux systems by hardening single user mode, guarding grub boot entries with a root password, and configuring systemd rescue and emergency targets.

Disable control-alt-delete to prevent reboot via keyboard remote access, safeguarding against bypassing single user mode. Configure the system to ignore c-a-d and reload the init settings.

Practice demonstrates configuring and using sudo to run commands as different users, inspecting permissions, validating configurations, and auditing sudo logs to enforce strict access control and prevent cross-user privileges.

Enforce sshd hardening by enabling stronger encryption and authentication. Restrict listen addresses with ListenAddress to private networks and change the default port to reduce exposure.

Explore file and directory modes, showing how read, write, and execute permissions govern accessing file contents, modifying data, running programs, and listing or creating items in directories.

Set file permissions in linux using numeric mode to read, write, and execute for user, group, and others (7 5 0) with chmod, then verify with ls.

Update the system and enable the epel repository, then install tripwire on CentOS 7. Create keys, initialize the database, configure policy, test with sample files, and schedule daily checks.