Function and Definition of Firewalls
📌 A firewall (cortafuegos) is a hardware device or software program that controls all traffic entering and exiting a network, acting as the first line of security.
🛡️ Its primary function is to permit access to safe traffic while blocking traffic deemed insecure or malicious.
🧑‍💻 Think of the firewall as a strict security guard analyzing every data packet against configured rules before allowing passage.

Types of Firewalls
🌐 Network Firewall (Perimeter Firewall): Strategically placed between the internal network and the internet, serving as the main external wall.
💻 Software Firewall: Installed directly on individual devices (PCs, laptops, servers) to provide local, personal device protection.
🚀 Next-Generation Firewalls (NGFWs): Advanced firewalls that perform deep packet inspection, detecting malware and offering granular control over application usage.

How Firewalls Operate
📦 Data packets, acting as digital identification, are checked based on four key criteria: origin, destination, port, and protocol.
✅ Traffic is permitted only if the combination of these factors matches established security rules (e.g., traffic on ports 80 for HTTP or 443 for HTTPS is usually allowed).
🚫 Malicious connections, such as those attempting to use ports commonly associated with bots (like port 666), are immediately detected and blocked.

Firewall in Action: DDoS Attack Example
🛑 In a Distributed Denial of Service (DDoS) attack, an attacker sends massive volumes of fake requests to overwhelm a public server.
🛡️ A well-configured firewall detects this anomalous traffic pattern, automatically filters, and blocks the false requests before they saturate the server.
✅ This filtering ensures the network continues operating normally, allowing real users access and neutralizing the cyberattack.

Key Points & Insights
➡️ Firewalls are fundamental infrastructure components, distinct from switches (which connect) and servers (which process); the firewall's role is purely protection.
➡️ Firewalls function as the silent guardian, working 24/7 to prevent unauthorized access, viruses, and attacks from reaching critical systems.
➡️ Configuring firewalls effectively is crucial because without them, all devices and user data are completely exposed to external threats.

📸 Video summarized with SummaryTube.com on Nov 09, 2025, 23:45 UTC