A firewall is a security system—hardware, software, or a combination of both—that monitors and controls incoming and outgoing network traffic based on predefined security rules.
Its primary purpose is to create a barrier between a trusted internal network and untrusted external networks (like the internet) to protect systems and data from unauthorised access, cyberattacks, and other security threats.
Types of Firewalls
1. Packet-Filtering Firewall: Examines individual packets of data and filters them based on rules like IP address, port, or protocol.
2. Stateful Inspection Firewall: Tracks the state of active connections and makes decisions based on the context of the traffic.
3. Proxy Firewall: Acts as an intermediary by handling requests from the client and forwarding them to the destination server, adding a layer of anonymity.
4. Next-Generation Firewall (NGFW): Combines traditional firewall features with advanced functionalities like intrusion prevention, deep packet inspection, and application awareness.
5. Web Application Firewall (WAF): Specifically protects web applications by filtering HTTP traffic to prevent attacks like SQL injection or cross-site scripting (XSS).
How It Works
1. Rules and Policies: Firewalls operate based on preconfigured rules that define what traffic is allowed or blocked.
2. Filtering: Incoming and outgoing data packets are analyzed. Suspicious or unauthorized traffic is blocked.
3. Logging and Monitoring: Firewalls log activity, helping administrators detect and respond to potential threats.
Why Use a Firewall?
• Protects against unauthorized access.
• Safeguards sensitive data.
• Blocks malware and cyberattacks.
• Helps enforce network policies.
• Facilitates secure remote access.