Network Security
Firewall
Also known as: Network firewall
Definition
A network security device or software that monitors and controls inbound and outbound traffic based on a defined ruleset, separating trusted from untrusted networks.
Examples
- A pfSense appliance blocking inbound SMB (TCP/445) from the internet.
- An AWS security group permitting only HTTPS from the load balancer to an application server.
Related terms
Next-Generation Firewall (NGFW)
An advanced firewall that combines stateful inspection with application awareness, integrated IPS, user-identity controls, and TLS inspection to enforce richer policies.
Web Application Firewall (WAF)
A reverse-proxy filter that inspects HTTP/HTTPS traffic to block web attacks such as SQL injection, XSS, and bot abuse before they reach the application.
Stateful Firewall
A firewall that tracks the state of active connections in a connection table and allows return traffic that matches an established session.
Packet Filtering
A network-security technique that inspects each packet's header fields and allows or drops it based on a static ruleset.
Intrusion Prevention System (IPS)
An inline security control that detects malicious traffic and actively blocks, resets, or scrubs it in real time.
Demilitarized Zone (DMZ)
Demilitarized Zone (DMZ) — definition coming soon.