CompTIA Linux+ Portable Command Guide: All the commands for the CompTIA XK0-004 exam in one compact, portable resource, 2nd Edition

Chapter 19. Given a scenario, implement and configure Linux firewalls

This chapter provides information and commands concerning the following topics:

Access control lists

• Source

• Destination

• Ports

• Protocol

• Logging

• Stateful vs. stateless

• Accept

• Reject

• Drop

• Log

Technologies

• firewalld (zones, run time)

• iptables (persistency, chains)

• ufw (/etc/default/ufw, /etc/ufw/)

• Netfilter

IP forwarding

• /proc/sys/net/ipv4/ip_forward

• /proc/sys/net/ipv6/conf/all/forwarding

Dynamic rule sets

• DenyHost

• Fail2ban

• IPset

Common application

• Firewall configurations (/etc/services, privileged ports)

Access Control Lists

A firewall (aka, access control list) is a network appliance (either hardware or software based) that is designed to either allow or block network ...