A firewall is a piece of security hardware or software that creates a wall between a reliable internal network and an unreliable external network, often the Internet. Its main goal is to monitor and manage network traffic by predetermined security rules.
Web applications are critical for modern businesses; however, they have also become popular targets for malicious activity. Firewalls are essential in protecting these applications from potential flaws and attacks.
There are two main types of firewalls: network firewalls and application firewalls.
Network Firewall
These firewalls can be implemented as hardware or software and function at the network level. At the network layer (Layer 3) OSI model, they filter traffic based on factors like IP addresses, ports, and protocols.
Application Firewall
It is known as a “web application firewall” (WAF) since it focuses mainly on securing web applications. They offer advanced security by examining application-layer traffic and enforcing particular security rules and policies. At the OSI model’s application layer (Layer 7), application firewalls control traffic.
Functionality
Packet Filtering
Firewalls examine individual network packets and apply filtering rules to allow or block them based on criteria such as source and destination IP addresses, ports, and protocols.
Stateful Inspection:
This method monitors the state of network connections and analyzes packet context to ensure that only legitimate connections are established so that unauthorized access attempts are avoided.
Proxy Service
Firewalls can act as go-betweens for clients and servers, validating and filtering requests before forwarding them. This protects the application’s internal infrastructure from direct exposure to the Internet.
Securing Web Applications with Firewall
Network Protection
Firewalls are essential to securing web applications by protecting the underlying network infrastructure. They act as the first line of defence, monitoring incoming traffic and blocking potentially malicious connections. Firewalls can identify and block traffic from known unwanted sources, preventing unauthorized access attempts and reducing the risk of successful attacks.
Access Control in Firewall
Firewalls enforce web application access control policies, determining which traffic is permitted and which is denied. They restrict application access to authorized sources by defining rules based on IP addresses, protocols, and ports. This also helps to prevent unauthorized users from accessing the application and reduces the attack surface.
Application Layer Filtering
Application layer filtering is a strength of advanced firewalls, particularly web application firewalls (WAFs). Firewalls can identify and block specific types of malicious traffic or application-layer attacks by inspecting the content and structure of network packets at the application layer. They can, for example, detect and prevent SQL injection and cross-site scripting (XSS) attacks, both of which are common vulnerabilities in web applications. This deep packet inspection allows firewalls to detect and block malicious payloads or abnormal patterns, significantly improving the web application’s security posture.
Virtual Private Network (VPN) Support
Firewalls can provide secure remote access to web applications by supporting virtual private networks (VPNs). VPNs create an encrypted tunnel between the user and the application, ensuring the confidentiality and integrity of data transmitted over the network. Firewalls verify that users can securely access the web application from untrusted networks or remote locations via secure remote connections.
Firewalls, on the other hand, are critical components of a comprehensive web application security strategy. Network security, access control, application layer filtering, intrusion detection, VPN support, and logging are all available. By leveraging the strengths of firewalls, organizations can significantly improve the security posture of their web applications, mitigating the risks posed by potential vulnerabilities and attacks. Firewalls, however, should be supplemented with other security measures such as secure coding practices, regular software updates, strong authentication mechanisms, and intrusion detection systems for robust and effective web application security.