Types of Firewalls

Different Types of Firewalls that You Should Know

There are different types of firewalls. What type you should use greatly depends on the scope and measure of protection that you need. Let us get to know the different types of firewalls.

Types of Firewalls

Beyond traditional firewall protection, firewall devices and services can provide intrusion detection and prevention (IDS/IPS), denial-of-service (DoS) attack protection, session monitoring, and other security services to protect servers and other devices within the private network. 

While certain firewalls can perform several functions, they must be part of a multilayered architecture that implements appropriate enterprise security rules.

Here are the different types of firewalls:

1. Packet filtering firewall

A Packet-filtering firewall is a firewall that filters incoming and outgoing packets based on the

information in each packet’s header.

2. Application-layer firewall

An application-layer firewall is a type of firewall that protects the application layer (Layer 7) of the OSI seven-layer network model.

3. Stateful inspection firewall

Stateful inspection firewalls are designed to prevent all traffic from entering or leaving a system; unless both ends of the communication channel have acknowledgement and approval. Also, stateful inspection firewalls maintain state information about each connection or session that traverses them; this information provides context for interpreting future connections or session requests. 

Any requests that do not match existing connections or sessions are denied, blocking potential attacks. Stateful inspection firewalls can detect and prevent certain types of DoS attacks. 

This type of firewall is also known as a “screening router”.

4. Intrusion prevention system firewall

Intrusion prevention system firewalls provide the same type of protection as a stateful inspection firewall, but they go a step further. intrusion prevention system firewalls monitor network traffic for patterns that match predefined security policies and block malicious attacks based on those patterns. 

For example, an IPS firewall might monitor the network for attempted buffer overflows. If detection, moreover, of a buffer overflow attack happens, the firewall takes action to block or mitigate that attack. 

A managed intrusion prevention system (IPS) acts in real-time to identify, report, and mitigate intrusions. A managed IPS can monitor traffic for malicious activity that is through other network security layers.

IPS devices management work in conjunction with other security technologies to provide multilayered protection for enterprises. 

5. Application-level gateway firewall

Application-level gateways work at the application layer of the OSI seven-layer model. They are by-design to intercept all data that is passed between two or more applications and inspect it before allowing it to be transmitted. Application-level gateways are also proxy firewalls, HTTP gateways, application proxies, proxy servers, reverse proxies, or IP proxies. 

They act as intermediaries between client applications and the Internet. Application-layer gateways are used to enforce security policies, filter outbound traffic, and block unauthorized requests, for instance. They are commonly used to restrict Web access for employees during non-working hours, monitor e-mail attachments for viruses, or limit access to specific Web sites. 

Application-level gateways are also used as an intermediary between clients and servers in a cloud computing environment. 

A reverse proxy is a type of application-level gateway that routes incoming requests to one or more servers for processing. When the response is returned from the server, the reverse proxy forwards it back to the original client. The reverse proxy can also cache the response for future requests.

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