What types of firewall are there?

#Main types of firewall

#1. Packet Filtering Firewall

The simplest type of firewall.

How it works:

• checks each packet individually;
• looks at IP addresses, protocols and ports;
• does not "remember" previous packets.

Pros:

• fast;
• simple to implement.

Cons:

• does not understand the connection's context;
• weak protection.

Works mostly at the network layer (L3).

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#2. Stateful Firewall

The most common type of firewall.

How it works:

• tracks connection state;
• understands which packet is a request and which is a reply;
• passes only legitimate traffic.

Pros:

• much safer than packet filtering;
• protects well against many attacks.

Cons:

• requires more resources.

Works at the network and transport layers (L3-L4).

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#3. Application Firewall (Application Layer Firewall)

A firewall at the application layer.

How it works:

• analyzes traffic content;
• understands application protocols (HTTP, FTP, SMTP);
• can block attacks at the application layer.

Pros:

• high accuracy;
• protection against attacks on applications.

Cons:

• slower;
• harder to configure.

Works at the application layer (L7).

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#4. Web Application Firewall (WAF)

A specialized firewall for web applications.

How it works:

• protects HTTP/HTTPS;
• blocks SQL injection, XSS and other web attacks.

Pros:

• excellent protection for websites;
• filters web traffic specifically.

Cons:

• protects only web applications.

Often used together with a regular firewall.

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#5. Proxy Firewall

Works as an intermediary between client and server.

How it works:

• the client connects to the proxy;
• the proxy connects to the server itself;
• there is no direct connection.

Pros:

• hides the internal network;
• can filter content.

Cons:

• latency;
• harder to administer.

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#6. Next-Generation Firewall (NGFW)

A modern, "smart" firewall.

What it can do:

• stateful filtering;
• application analysis;
• IDS/IPS;
• user control;
• SSL inspection.

It effectively combines several security tools in one.

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#Brief comparison