What Is a Firewall and How Does It Protect Your Network?
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A simple analogy is that of a bouncer standing at the door to your business club, checking IDs and ensuring that only people on the invite list are allowed inside.
What Is a Firewall?
A firewall is a network security device or system that monitors and controls network traffic based on predefined security rules. A firewall acts as a digital barrier between trusted internal networks and devices, and untrusted external networks, like the internet.
Firewalls are front-line defense for your digital assets like employee data, proprietary company information, and Intellectual Property (IP) and details about your network infrastructure. They come in hardware form, as well as software applications or cloud-based services, as part of Networking as a Service (NaaS) or Firewall as a Service (FWaaS) offerings.
How Firewalls Work
We likened a firewall’s job to that of a bouncer earlier, but we could just as easily say a building security guard. Anyone entering or leaving your office building passes the security desk or checkpoint, where staff use their badge to swipe in and the guard checks ID for visitors. They compare this ID to a roster of expected people, maybe for an interview or board meeting, before issuing them a day pass and letting them enter the building.
This is analogous to a firewall checking all incoming data packets against its list of predetermined rules to check their veracity and only allowing in those that meet the guidelines (expected guests) or have a valid signature (building badge).
The basic flow of data through a firewall looks something like this:
- Initial validation – ensuring the packet is properly formed and valid
- Rule matching – the firewall checks for source/destination IP addresses, port numbers and other restrictions, looking for a match
- Connection state analysis – the firewall checks whether the packet belongs to an existing connection and verifies whether the packet is part of an established session
- Deep content analysis – if enabled, an advanced firewall will examine the actual content of the data packet, not just the header information
- Policy decision – a binary decision is made to either ALLOW or DENY the packet entry to the network
- Packet forwarding or blocking – approved packets are forwarded to their destination, and blocked ones are discarded
Keep in mind that the above process occurs in a matter of milliseconds to keep data flows uninterrupted from the user’s perspective.
What Does a Firewall Do?
Protecting Against Threats
Modern firewalls are designed to block multiple attack vectors, and they are scalable and upgradable so that when new attack types are discovered, they can quickly be blocked. Some examples of ways a firewall protects your network are:
Unauthorized access prevention
A firewall can block suspicious IP addresses or geographic regions known to house malicious actors, preventing brute force attacks and other unauthorized login attempts.
Malware and ransomware protection
Firewall rules can identify and block known malicious signatures and prevent “command and control” communications.
DDoS attack mitigation
Firewall settings like rate limiting, traffic shaping, packet validation and suspicious traffic filtering provide further control over what traffic is and isn’t allowed to enter your network by integrating with professional-grade DDoS protection services.
Advanced persistent threat (APT) prevention
Monitoring connection patterns on an ongoing and long-term basis allows a firewall to detect unusual outbound traffic that can indicate data exfiltration (data theft).
Monitoring and Control
The operational benefits of a modern firewall solution include:
Traffic monitoring
Firewalls provide real-time visibility into network activity and use patterns. They also allow bandwidth monitoring, application identification, user activity tracking and behavioral analysis.
Policy enforcement
Automated rule application and compliance checking keep your network operating smoothly, while centralized management across locations allows your IT team to monitor everything from wherever they are.
Compliance and risk reduction
Features like audit logging allow you to stay on top of regulatory requirements, conduct risk assessments and respond to incidents with detailed forensic data.
What Are the Types of Firewalls for Cyber Security?
Packet-Filtering Firewalls
Proxy Firewalls
Stateful Inspection Firewalls
Next-Generation Firewalls
This category of firewall focuses on advanced security via application awareness, intrusion detection and deep packet inspection. Further advanced features include:
- User identification and identity-based policy enforcement
- TLS/SSL traffic inspection for encrypted threat detection
- Integration with threat intelligence feeds for real-time protection
- Sandboxing for zero-day threat analysis
A next-generation firewall provides centralized control across hybrid environments while enabling advanced processing without significant latency. Its management console is unified, single-pane-of-glass.
Virtual and Cloud-Based Firewalls
For a modern business that operates across a dispersed network, this is often the best option, being specifically designed for distributed enterprise environments. Additional benefits to virtual and cloud-based firewall systems include:
- Full visibility and control across multi-cloud deployments
- Consistent policy enforcement regardless of specific infrastructure layout
- Elastic scalability
- Pay-as-you-go cost models
- Reduced administrative overhead
GTT integrates cloud security with our FWaaS offering for enterprise-grade cloud firewall solutions.
Choosing the Right Firewall
Do a quick assessment of your network architecture. Do you operate a single location, or are your operations dispersed across multiple? What’s your level of cloud adoption? Do you already support a hybrid environment? What are the security requirements of your remote workforce (if you have one)?
Then evaluate the options based on some key criteria:
- Level of integration with existing systems and tech stacks
- Managed support options and requirements for network expertise
- Total cost of ownership (TCO), including licensing and management
Beyond these basics, it’s also important to consider more advanced options, like compatibility with zero trust architecture, global connectivity needs (SD-WAN) and your requirements for cloud security service integration. For a holistic network assessment, consider a comprehensive platform evaluation from GTT.
Best Practices for Firewall Management
If you already have a firewall in place, it’s a good idea to audit your configuration to ensure it’s up to current security standards. This is by no means intended to be a comprehensive guide, but a few fundamentals to check on are:
- Use a “default deny” policy to block all traffic unless or until it is explicitly allowed.
- Set role-based access controls (RBAC) for user permissions across the organization.
- Audit your firewall rules to remove those that have become obsolete or that have come into conflict with newer rules.
- Automate alerts for unusual access attempts or other security events.
- Test new rules in a sandboxed environment before deploying to production.
Advanced management tools that can provide additional value:
- Secure Access Service Edge (SASE) integration for unified security and networking
- Automation of routine security tasks and incident response protocols
- Cloud-based management console for distributed environments
Protect Your Network with GTT
GTT provides comprehensive advanced firewall and security solutions for complex business networks and use cases. Our solutions integrate next-generation firewalls with cloud security and managed services to bring you exactly the level of protection you need, including:
- Global scalability – support for multi-location enterprises with consistent security policies
- Expert management – professional security operations and 24/7 monitoring services
- Future-ready architecture – our cloud-first approach supports digital transformation initiatives
Ready to strengthen your network security? Explore GTT Secure Networking, then talk to our experts about how GTT’s advanced firewall solutions can protect your business from evolving cyber threats while supporting your growth objectives.
What is the purpose of a firewall?
A firewall’s primary purpose is to create a security barrier between trusted internal networks and untrusted external networks. They act as a first line of defence against cyber threats, unauthorized access and malicious actors.
How do I check my firewall?
- Simple status verification: check the management console for operational status and active rules.
- Log review: Examine your firewall logs for blocked packets, access attempts and other security events.
- Rule validation: Verify that current rules are aligned with business needs and security policies.
- Performance monitoring: Check throughput, latency and resource utilization to ensure smooth network operations.
- Professional assessment: consider a third-party audit for a more comprehensive security evaluation.
Do all devices need a firewall?
Enterprise firewalls protect the entire network, not individual devices. For devices that travel outside of this perimeter, a software firewall may be beneficial.
Is a firewall or VPN better?
Firewalls and VPNs are complementary technologies, not competitors, as they offer different yet related services. A firewall protects your network perimeter and controls traffic flow based on established security policies. A VPN encrypts data transmissions and provides secure remote access to your network for your remote workforce. It is best practice to use both technologies for a comprehensive security architecture by deploying firewalls for network protection and VPNs for secure remote connectivity.
Learn more about how GTT can help support your business collaboration, mobility and growth
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