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Three Types of Web Application Firewalls (WAF)

A web application firewall, or WAF, is a security solution that monitors, filters, and blocks data packets flowing in and out of an online application or website. WAFs are often install using reverse proxies in front of an application or website and can be host-based, network-based, or cloud-based (or multiple apps and sites). 

WAFs can be deploy as network appliances, server plugins, or cloud services, scanning each packet and evaluating application layer (Layer 7) logic to filter out questionable or harmful traffic based on rules.

What Is the Importance of WAF Security? 

WAFs are crucial for app developers, social media corporations, and digital banks that sell online. A WAF can protect sensitive data including client details and credit card information.

Much of an organization’s sensitive data is often stored in a backend database that may be accessed via web apps. Mobile applications and IoT devices are rapidly being used by businesses to ease commercial interactions, with many online transactions taking place at the application layer. Attackers frequently target programmes in order to gain access to this information. 

A WAF can assist you in meeting compliance standards such as PCI DSS (Payment Card Industry Data Security Standard), which applies to any firm that handles cardholder data and mandates the implementation of a firewall. As a result, a WAF is an important part of every organization’s security strategy.

While having a WAF is necessary, combining it with other security measures like intrusion detection systems (IDS), intrusion prevention systems (IPS), and traditional firewalls to establish a defense-in-depth security paradigm is advised.

Types of Web Application Firewalls

A WAF may be implement in three different ways: 

WAF based on a network — 

It is often hardware-based and deployed locally to reduce latency. This is, however, the most expensive sort of WAF since it needs the storage and maintenance of physical equipment. 

WAF depending on the host— 

May be completely integrate into an application’s software This approach is less expensive and more configurable than network-based WAFs, but it requires a lot of local server resources, is difficult to set up, and can be costly to maintain. Often, the machine that runs a host-based WAF must be harden and modified, which takes time and money.

WAF in the cloud— 

Security-as-a-service is a cost-effective, easy-to-implement solution that typically requires no upfront expenditure. A cloud-based WAF can be upgrade without cost or user effort. Since a third party will manage your WAF, make sure cloud-based WAFs can be customise to match your company’s needs.

WAF Technology 

A WAF can be integrate into server-side software plugins or hardware appliances, or it can be provided as a service for traffic filtering. WAFs can serve as reverse proxies and protect web programmes from malicious or hacked endpoints (as opposed to a proxy server, which protects users from malicious websites). 

WAFs check every HTTP request for security. Fraudulent traffic can be detect via device fingerprinting, input device analysis, and CAPTCHA challenges.

WAFs are pre-loading with security rules that can identify and block a variety of known attack patterns, including the Open Web Application Security Project’s top web app security flaws (OWASP). 

Additionally, the company may create custom rules and security policies to fit the application’s business logic. Configuring and customizing a WAF may need specialized knowledge.

Models of WAF Security 

WAFs can employ either a positive or negative security model, or a hybrid of both: 

Model of positive security— 

A whitelist filters traffic according to a list of approved components and activities in the positive WAF security paradigm; anything not on the list is prohibiting. This architecture has the advantage of being able to stop new or undiscovered assaults that the creator did not expect. 

Negative security model—

the negative security model uses a blacklist (or deny list) that only bans specified things; everything that isn’t on the list is permitting. Although this strategy is simpler to adopt, it does not ensure that all dangers are addressing. It also necessitates the maintenance of a potentially extensive collection of harmful signatures. The amount of constraints in place determines the level of security. 


A Web Application Firewall (WAF) is a type of security measure that can be use to protect web applications from malicious or hacked traffic. WAFs come in different forms, including network-based, host-based, and cloud-based, and can employ either a positive or negative security model. Configuring and customizing a WAF may need specialized knowledge.

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