---
title: firewall
slug: Glossary/firewall
tags:
  - DDoS
  - Firewall
  - Glossary
  - Security
  - computer network
---
A **firewall** is a system that filters network traffic. It can either let it pass or block it, according to some specified rules. For example, it can block incoming connections aimed at a certain port or outgoing connections to a certain IP address.

Firewalls can be as simple as a single piece of software, or more complex, like a dedicated machine whose only function is to act as a firewall.

## See also

- {{Interwiki("wikipedia", "Firewall (computing)")}} on Wikipedia
