Linux Networking

6.

Network Security and Packet Filtering

6.1.

Firewall Concepts

6.1.1.

Packet Filtering Principles

6.1.1.1.

Filtering Criteria

6.1.1.2.

Ingress vs Egress Filtering

6.1.1.3.

Default Policies

6.1.2.

6.1.2.1.

Stateful Firewalls

6.1.2.2.

Stateless Firewalls

6.1.2.3.

Application Layer Firewalls

6.1.3.

Network Address Translation (NAT)

6.1.3.1.

Source NAT (SNAT)

6.1.3.2.

Destination NAT (DNAT)

6.1.3.3.

Port Address Translation (PAT)

6.1.3.4.

6.2.

iptables Framework

6.2.1.

iptables Architecture

6.2.1.1.

Netfilter Framework

6.2.1.2.

Tables and Chains Concept

6.2.2.

iptables Tables

6.2.2.1.

6.2.2.1.1.

6.2.2.1.2.

6.2.2.1.3.

6.2.2.2.

6.2.2.2.1.

PREROUTING Chain

6.2.2.2.2.

POSTROUTING Chain

6.2.2.2.3.

6.2.2.3.

6.2.2.3.1.

Packet Modification

6.2.2.3.2.

Quality of Service

6.2.2.4.

6.2.2.4.1.

Connection Tracking Bypass

6.2.3.

6.2.3.1.

Rule Syntax and Structure

6.2.3.2.

6.2.3.3.

6.2.3.3.1.

6.2.3.3.2.

6.2.3.3.3.

6.2.3.3.4.

6.2.3.3.5.

6.2.3.3.6.

6.2.3.3.7.

MASQUERADE Target

6.2.4.

iptables Management

6.2.4.1.

Rule Addition and Deletion

6.2.4.2.

Rule Ordering and Priorities

6.2.4.3.

Saving and Restoring Rules

6.2.4.4.

Making Rules Persistent

6.3.

nftables Framework

6.3.1.

nftables Introduction

6.3.1.1.

Motivation and Benefits

6.3.1.2.

Comparison with iptables

6.3.2.

nftables Architecture

6.3.2.1.

Tables, Chains, and Rules

6.3.2.2.

Rule Evaluation Process

6.3.3.

nft Command Usage

6.3.3.1.

6.3.3.2.

Table Management

6.3.3.3.

Chain Management

6.3.3.4.

Rule Management

6.3.4.

Advanced nftables Features

6.3.4.1.

6.3.4.2.

Variables and Includes

6.3.4.3.

Scripting Support

6.4.

High-Level Firewall Tools

6.4.1.

6.4.1.1.

Zone-Based Configuration

6.4.1.2.

Service Definitions

6.4.1.3.

Runtime vs Permanent Configuration

6.4.1.4.

6.4.1.5.

Integration with Backend

6.4.2.

ufw (Uncomplicated Firewall)

6.4.2.1.

Basic Usage and Syntax

6.4.2.2.

Application Profiles

6.4.2.3.

Logging Configuration

6.4.2.4.

Status and Management

6.5.

SELinux and AppArmor Network Security

6.5.1.

Mandatory Access Control Overview

6.5.2.

SELinux Network Controls

6.5.2.1.

6.5.2.2.

Network Object Classes

6.5.2.3.

Boolean Settings

6.5.3.

AppArmor Network Controls

6.5.3.1.

6.5.3.2.

Profile Configuration

6.5.4.

Troubleshooting Access Denials

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