Linux Security and Hardening: A Practical Approach

Introduction

• About Security

• Tips & Tricks

Physical Security of a Linux Box

• Overview of Physical Security

• BIOS Firmware Security

• Set BIOS Password

• Single User Mode Security

• How to set password at Single User Mode

• Securing Boot Loader

• Section Summary

• Project Assignment: Securing Single User Mode in Linux

• Project Assignment: Securing the Boot Loader in Linux

PAM (Pluggable Authentication Modules)

• Overview of PAM Security

• Concepts of PAM

• PAM Modules & Configurations

• PAM Module Groups

• Control Flags in PAM

• PAM Modules

• Project Assignment on PAM – Pluggable Authentication Modules

• Quiz

Account Security

• Overview of User Account Security

• User Account Information

• Forcing strong passwords

• Pam_pwquality – Password strength-checking

• Security by Account Locked

• Account Locked using pam_faillock PAM module – Lab Session

• Understanding Password Aging Policy

• Practice Lab Session

File System Security

• Overview of File & Directory Permission

• Access mode

• Change Permission & Ownership

• Special Permissions

• ·Setuid, Setguid, Sticky bit, ACL, etc

• ACL

• Controlling files with ACL

• ACLs demo

• Practice Lab Session

General Security

• Keep your system updated

• Disable USB stick

• Turn off IPv6

• Restrict users to use old passwords

• Check password expiration

• Verify accounts for Empty password

• Verify accounts for “Zero” UID

• Review logs regularly

• Keep /boot as read only

Network Security

• Overview of Network Security

• Openssh Security

• Securing SSHD

Linux Firewall

• Firewall concepts

• About nftables, features, and advantages of firewalld

• Firewalld components, pre-defined zones

• How packet flows through the firewall

• Check firewalld services – Lab Session

• Adding and Removing Services & Port from Firewall Server – Lab Session

• Add Services Permanently in Firewalld – Lab Session

• Add HTTP Service in firewalld – Lab Session

• Port forwarding – Lab Session

• Conceptual discussion about Masquerading, Packet Flow in Firewalld

• Masquerading with Port Forwarding – Lab Session

• About Rich Rules in Firewalld

• Specifically allow a Server using Rich Rules – Lab Session

• Allow Telnet Port, SSH with log-prefix using Rich Rule – Lab Session

• Accept, Reject, Drop – Lab Session

Managing SELinux Security

• Introduction – SELinux

• SELinux Security Concepts

• Changing SELinux Modes

• Practice Lab Sessions

• Changing SELinux Contexts

• SELinux Booleans

• Audit logs & troubleshooting SELinux

• Last lecture