# firewall

> network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules

**Wikidata**: [Q80998](https://www.wikidata.org/wiki/Q80998)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Firewall_(computing))  
**Source**: https://4ort.xyz/entity/firewall

## Summary
A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between trusted internal networks and untrusted external networks, such as the internet, to prevent unauthorized access and cyber threats.

## Key Facts
- A firewall is a network security system that monitors and controls network traffic based on security rules.
- It is part of the broader category of computer appliances, which are single-purpose computing devices.
- Firewalls can be classified into various types, including personal firewalls, application firewalls, stateful firewalls, and packet filters.
- Notable firewall software includes OPNsense (launched in 2015), pfSense, and SmoothWall.
- Firewalls are essential components of network security, helping to prevent unauthorized access and cyber attacks.

## FAQs
### Q: What is the primary function of a firewall?
A: The primary function of a firewall is to monitor and control incoming and outgoing network traffic based on predetermined security rules, acting as a barrier between trusted and untrusted networks.

### Q: What are the different types of firewalls?
A: Firewalls can be classified into several types, including personal firewalls, application firewalls, stateful firewalls, packet filters, and next-generation firewalls.

### Q: What is a personal firewall?
A: A personal firewall is a type of firewall designed to protect a single personal computer from unauthorized access and cyber threats.

### Q: What is an application firewall?
A: An application firewall is a form of firewall that controls input/output or system calls of an application or service, providing an additional layer of security.

### Q: What is a stateful firewall?
A: A stateful firewall is a connection tracking network security system that monitors the state of active connections and makes decisions based on the context of the traffic.

## Why It Matters
Firewalls play a crucial role in network security by acting as a barrier between trusted internal networks and untrusted external networks. They help prevent unauthorized access, cyber attacks, and data breaches, ensuring the integrity and confidentiality of sensitive information. Firewalls are essential for both personal and enterprise networks, providing a first line of defense against a wide range of cyber threats. By monitoring and controlling network traffic, firewalls help maintain the availability and performance of network resources, making them a fundamental component of modern cybersecurity strategies.

## Notable For
- Being a fundamental component of network security, providing a barrier between trusted and untrusted networks.
- Offering various types and configurations, including personal firewalls, application firewalls, and stateful firewalls, to suit different security needs.
- Being implemented in both hardware and software forms, providing flexibility in deployment.
- Playing a critical role in preventing unauthorized access, cyber attacks, and data breaches.
- Being widely adopted in both personal and enterprise environments, highlighting their importance in modern cybersecurity.

## Body
### Overview
A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between trusted internal networks and untrusted external networks, such as the internet, to prevent unauthorized access and cyber threats.

### Types of Firewalls
Firewalls can be classified into several types, each with its own specific features and use cases:
- **Personal Firewall**: Designed to protect a single personal computer from unauthorized access and cyber threats.
- **Application Firewall**: Controls input/output or system calls of an application or service, providing an additional layer of security.
- **Stateful Firewall**: Monitors the state of active connections and makes decisions based on the context of the traffic.
- **Packet Filter**: Inspects packets transferred between computers and blocks or allows them based on security rules.
- **Next-Generation Firewall**: A term used to describe advanced firewall systems that offer additional features and capabilities beyond traditional firewalls.

### Notable Firewall Software
Several notable firewall software solutions are widely used in both personal and enterprise environments:
- **OPNsense**: An open-source firewall launched on January 2, 2015, known for its flexibility and extensive feature set.
- **pfSense**: An operating system and firewall that provides advanced networking and security features.
- **SmoothWall**: A firewall Linux distribution designed for ease of use and robust security.
- **Little Snitch**: An application firewall for macOS that monitors and controls outgoing network connections.
- **Gufw**: A GUI frontend for ufw (Uncomplicated Firewall), providing a user-friendly interface for managing firewall rules.

### Implementation and Deployment
Firewalls can be implemented in both hardware and software forms, providing flexibility in deployment. Hardware firewalls are typically used in enterprise environments to protect entire networks, while software firewalls are commonly used on individual computers to provide personal protection. Firewalls can also be deployed as virtual appliances, running entirely within a virtualized environment.

### Role in Network Security
Firewalls play a critical role in network security by acting as a barrier between trusted and untrusted networks. They help prevent unauthorized access, cyber attacks, and data breaches, ensuring the integrity and confidentiality of sensitive information. Firewalls are essential for both personal and enterprise networks, providing a first line of defense against a wide range of cyber threats.

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "firewall",
  "description": "network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules",
  "url": "https://en.wikipedia.org/wiki/Firewall_(computing)",
  "sameAs": ["https://www.wikidata.org/wiki/Q1551807", "https://en.wikipedia.org/wiki/Firewall_(computing)"],
  "additionalType": "computer appliance"
}

## References

1. [Source](https://github.com/JohnMarkOckerbloom/ftl/blob/master/data/wikimap)
2. Freebase Data Dumps. 2013
3. YSO-Wikidata mapping project
4. National Library of Israel
5. [firewall · GitHub Topics · GitHub](https://github.com/topics/firewall)
6. [firewalls · GitHub Topics · GitHub](https://github.com/topics/firewalls)