Network firewall What is a network firewall?
A network firewall is hardware or software that restricts and permits the flow of traffic between networks. Network firewalls help prevent cyberattacks by enforcing policies that block unauthorized traffic from accessing a secure network.
- Network firewalls explained
- What does a network firewall do?
- How does a network firewall work?
- Which network firewall is best?
- Benefits of network firewall security
- How network firewalls work
Network firewalls explained
Network firewalls are designed to limit the flow of traffic between networks. They are often employed between a secure private network and a network with a different security posture, such as the Internet. Network firewalls can also be placed throughout a secure private network to reduce the risk of cyberattacks and prevent unauthorized access to sensitive resources.
Types of firewalls
Firewall type | What it does |
|---|---|
| Packet filtering firewall | Inspects ingress (incoming) and egress (outgoing) traffic and allows/denies passage of the traffic based on basic information like source and destination. A packet filtering firewall does not keep track of the state of incoming or outgoing traffic, and thus is also known as a stateless firewall. Due to their limitations, stateless packet filtering firewalls can be vulnerable to attacks and exploits targeting the TCP/IP stack. |
| Stateful firewall | Utilizes stateful inspection to track traffic and block traffic that deviates from expected patterns. Stateful firewalls check connections against established connections tracked in a table and can deny traffic based on rules and non-conformity with established connections. This allows stateful firewalls to protect against attacks like Distributed Denial of Service (DDoS). |
| Application firewall | Builds on statefulness capabilities with deep packet inspection functionality. Application firewalls analyze data at the application layer, comparing observed events to established patterns of activity to identify deviations and prevent threats. Application firewalls can thwart attacks carried out by unexpected commands, such as buffer overflow attacks, DoS attacks, and malware. |
