The shift towards digitalization and establishing online presence is increasing greatly. With that, cyber security has become a necessity, not an alternative. In a world where we stay connected 24/7, there are threats and vulnerabilities everywhere, from smartphones to cloud servers.
Having a robust network without a firewall is just similar to a house without a lock on the door. In such a case, anyone can walk into the house, take what they want and may leave without hesitation. The result is almost similar. This is where the firewalls fall in and protects your network.
In this article, we will guide you through what a firewall is, how firewalls work and its importance in the digital world. Let’s get started!
What is a Firewall?
A firewall can be defined as a security system that regulates the incoming and outgoing network traffic depending on the set of predetermined rules. It acts as a layer that separates a trusted internal network such as your home, office wi-fi from an untrusted network like the internet. The key features of a firewall are:
- Block unauthorized access.
- Facilitates legitimate communication
- Controls suspicious activity
- Protects sensitive data
Basically, the firewalls play the role of gatekeepers and maintain the security level of your computer. The rules can be organized by data points like IP address, domain name, port number, protocols, and packet content. The firewall can easily block, ignore, or redirect the traffic once the suspicious activity is detected. As a result, firewalls help safeguard your digital ecosystem.
How Firewalls Function?
The firewall functions in a very simple way. When data passes into or out of your network, a firewall inspects that data looking at source/destination IP address, the ports, the protocols, and even the content of the data. The firewall decides to allow or block that data, based on rules you specified. To get a clear idea, it is essential to have a look at them from the OSI model (Open Systems Interconnection). The OSI has seven layers mentioned below:
Physical Layer – Basically, it carries out the hardware transmission.
Data Link Layer – MAC addresses, Ethernet; typically irrelevant to firewall concerns.
Network Layer (Layer 3) – Firewalls that filter packets operate here, as this is where packet filtering occurs. The firewall examines the IP address and routes accordingly.
Transport Layer (Layer 4) – The TCP/UDP ports. Stateful firewalls maintain connection tables at the transport layer level.
Session Layer (Layer 5) – Circuit level gateways operate here maintaining TCP handshakes.
Presentation Layer (Layer 6) – Data format/security, some advanced inspection firewalls operate at this layer.
Application Layer (Layer 7) – Proxy firewalls and Web Application Firewalls (WAF) inspect actual data like HTTP requests or SQL queries.
Different Types of Firewall
When it comes to protecting your digital assets, each type of firewall has its own advantages and disadvantages, along with its own ideal environment. Let’s take a look at each of them!
Static Packet-Filtering Firewalls
The static packet-filtering firewalls inspect the packet header for source address, destination address, protocol (TCP or UDP), and port numbers, and match information against a static set of rules. If the packet matches any of your approved banners, the bridge comes down and the packet goes through. If it does not match your pre-approved banners, the packet goes and never returns. It is fast, cost-effective and ideal for small offices that do not have continuous traffic changing patterns.
Stateful Inspection Firewalls
A stateful inspection firewall not only processes packets individually, it monitors the state of each connection. It generates a table of active TCP connections, that shows return traffic from a legitimate request is permitted automatically, and unexpected traffic is blocked.
Proxy (Application-Layer) Firewalls
A proxy firewall acts as the middleman (known as a proxy), it will end the connection again from the client side, then create a new connection to the destination server. This allows it to parse the application-specific protocols like HTTP, FTP, SMTP and prevent dangerous content from being downloaded such as blocking SQL injection attempts or distorted web requests.
Circuit-Level Gateways
A circuit-level gateway firewall operates at the session layer; it watches TCP handshakes and establishes a circuit, if both parties have authenticated themselves. Once the session is established, however, it does not look at the data itself.
Software (Host-Based) Firewalls
A software firewall resides on a PC, laptop, or server. It is similar to a personal bodyguard for a single device. For computer users, they use Windows Defender Firewall, or the built-in macOS firewall. This type of firewall allows individuals to define which applications are allowed to have listening ports opened or which applications can initiate outbound connections.
Hardware Firewalls
For organizations such as enterprises, with large, complex networks, a hardware firewall is a dedicated appliance. It inspects packets at demoralizing line speeds and typically includes a combination of the firewall types like packet filtering, and stateful inspection. Hardware firewalls are highly scalable, versatile, and offer centralized management for multiple users.
Cloud Firewalls
In the cloud firewalls, the firewall can live in the cloud. Additionally, it does not require hardware to install or maintain. They protect cloud workloads, and remote users via globally distributed points of presence. The cloud firewalls are highly scalable, easy-to-upgrade and consistent across hybrid environments.
Hybrid Firewalls
No single solution works for every situation, so many organizations deploy hybrid architecture using several kinds of firewalls. For example:
- A portable or hardware firewall at the perimeter
- Proxy based WAF in front of public web servers
- Stateful inspection for branch office VPNs
- Host based software firewalls on sensitive endpoints
- FWaaS to cover remote workers and cloud resources
Virtual Firewalls
Virtual firewalls provide micro-segmentation and isolation of traffic that exists between virtual machines or containers. It requires a granularity policy without needing to do product caching for physical hardware.
Advantages of Firewalls
Firewalls are fundamental building blocks that help build trust, resilience, and security for any networked environment. Let’s explore some of the benefits!
Traffic Control & Monitoring
A firewall allows you to define what specific traffic is in and out of your network. You can define policies and rules to block unwanted applications, malicious IPs, and suspicious ports which help keep threats away.
Protection from External Threats
It is one of the most recognizable benefits. Firewalls defend against hackers, malware, unauthorized access, and denial-of-service (DoS) attacks by filtering and inspecting incoming traffic.
Internal Segmentation
Advanced firewalls can assist with your segmentation of your internal network. An organization can logically separate the finance department from the HR department while simultaneously being on the same physical network, allowing for a reduction of lateral spread in the event of a threat.
Logging of Activities and Alerts
Firewalls can log traffic data which your IT team can use to spot suspicious activities and help with forensic investigations. Additionally, any breach can generate real-time alerts.
Policy Enforcement
Firewalls can help secure a company’s policies for using applications, accessing company VPN resources, and the flow of data across the organization.
Remote Access Protection (VPN)
Firewalls can offer network access protection to their users through a VPN, thereby establishing secure tunnels for remote workers, protection of communications, confidentiality, and integrity of communications.
Cost-Effective
By preventing breaches to a network, downtime, and data loss, firewalls give businesses huge potential savings, lowering risk of revenue loss and reputation.
Highly-Flexible
From hardware firewalls to FWaaS, businesses can select deployment types that fit their infrastructure whether it is on-premises, cloud-native and even hybrid.
Compliance Regulations
Firewalls support compliance with data protection laws like GDPR, PCI-DSS, HIPAA, etc. through controls and carry audit of sensitive data.
Final Thoughts
In the digital world, whether you are a business keeping customer details safe, or a remote employee keeping your laptop safe, a firewall should be your top priority.
It enables your network to operate safely, confidently, and with control. Additionally, it gives visibility to stop threats, enforce rules, and respond quickly if something goes wrong.
Frequently Asked Questions
Define a firewall and how does it work?
A firewall refers to a security system that can regulate and monitor incoming and outgoing network traffic. It operates according to a defined set of security rules by inspecting where packets come from and to where packets are going to.
What does a firewall do?
One of the primary roles of a firewall is to act as a ‘barrier’ to protect the internal workings of your computer, network or application, from outside interference. A firewall can ensure that only authorized traffic may be across the network, by stopping unauthorized access, preventing data leaks, and stopping cyberattacks.
What types of firewalls are there?
There are many different types of firewalls:
Packet Filtering Firewall
Stateful Inspection Firewall
Proxy Firewall
Circuit-Level Gateway Firewall
Software Firewall
Hardware Firewall
Cloud Firewall
Hybrid Firewall
Virtual Firewall
Each type of firewall has a different purpose, depending on your existing infrastructure and security requirements.
What is firewall vs antivirus?
A firewall protects your network by filtering traffic in and out of your network connection. An antivirus protects your devices or workstations against malware by detecting and cleaning it.
What is Network Address Translation (NAT) associated with firewalls?
NAT enables the firewall to translate, hiding the IP address within the firewall and replacing it with its public IP. NAT provides better privacy and security, hence not allowing any direct access to any internal hardware in the user’s setting.
What is a virtual firewall?
A virtual firewall is a software-only firewall that is installed in a virtualized environment such as cloud sites or data centres. It can provide the same function as physical firewalls, but has an optimized solution for working in dynamic, virtual workloads.
Is a firewall sufficient in securing a network?
No. A firewall is an important layer, but it should be used with other layers such as antivirus, intrusion detection systems, encryption, and strong authentication.
