How Network Firewall Work
Network firewalls are deployed in line with traffic entering or leaving a protected network. As traffic passes through the firewall, it inspects it and permits or blocks it, depending on predefined firewall policy and other factors.
The most basic types of firewalls look only at a packet’s header and make decisions based on its content. More advanced firewalls — such as next-generation firewalls (NGFWs) — also inspect the contents of the packet payload and incorporate other security technologies, such as intrusion prevention systems (IPS) and application control.
The most sophisticated firewalls are also able to decrypt encrypted traffic (HTTPS) in order to perform Layer 4 – 7 deep packet inspection and apply comprehensive threat prevention against any hidden attacks.
Benefits of Network Firewall
Firewalls are a vital network security technology and provide various benefits, including:
- Improved Security Posture: Firewalls define network boundaries and filter the traffic flowing through them. This enhances security policies by enabling the firewall to identify and block inbound threats or attempted exfiltration of sensitive data from the network.
- Access Management: Firewalls can manage remote access to corporate systems and software over the network. This is especially true of more advanced firewalls that can understand application traffic and block unauthorized access attempts.
- Network Visibility: Firewalls can see all traffic that passes through them. By monitoring and logging this traffic, they can provide insight into the types of traffic flowing over the network and how it is being used.
- Network Segmentation: Firewalls are commonly used to break a corporate network into segments. These segments help to prevent lateral movement through the network by malware or other intrusions.
Common Network Firewall Techniques and Features
Network firewalls are tasked with defining and securing network boundaries. To accomplish this, they offer various capabilities, such as:
- IP and Domain Filtering: Even the simplest firewalls can manage packets based on their source or destination IP addresses. This enables an organization to explicitly allow or deny malicious traffic from certain IP addresses or domains.
- Port Blocking: Different applications communicate using specific TCP or UDP ports. Firewall rules can also filter network traffic based on source and destination ports, limiting the types of traffic that are allowed to enter or leave the network.
- VPN Support: Firewalls commonly incorporate the ability to act as the terminus of a VPN connection. This enables secure connectivity between the different sites of a corporate network or between remote workers and the enterprise network.
- Application Awareness: NGFWs can inspect network traffic payloads and understand various types of application-specific traffic. This allows them to implement controls based on the specific application rather than just IP addresses and port numbers.
- Intrusion Detection and Prevention: NGFWs also integrate IPS functionality as well as the core capabilities of a firewall. This enables them to identify a wide range of potential threats attempting to enter the corporate network or cross segment boundaries.
The Various Types of Network Firewall Solutions and Technologies
Firewalls have existed for decades and have evolved significantly in that time to address new and emerging threats. Some of the main types of firewalls include:
- Packet Filtering: Packet filtering or stateless firewalls are the simplest type of firewall. They look at the packet header — including source and destination IP addresses — and make a determination based on predefined security rules.
- Stateful Inspection: Stateful inspection firewalls expand on packet filtering firewalls by tracking the current state of a network connection. This enables them to identify and block network packets that are not valid in context, such as a DNS response without a corresponding request.
- Proxy Services: Proxy firewalls are designed to conceal the identity of one of the communicating parties. All traffic sent by the hidden system appears to originate from the proxy firewall itself.
- NGFWs: NGFWs are the most advanced firewalls, incorporating various security functions beyond those of a stateful firewall. These include deep packet inspection, IPS, advanced threat prevention, and the ability to ingest and use threat intelligence.
Beyond the main types of firewalls, firewalls can also be deployed in various form factors. These range from hardware firewalls to virtual appliances to cloud-native firewall as a service (FWaaS) offerings.
Quantum Force - AI-Powered Network Firewalls and Security Gateways
While many different types of firewalls exist, protecting against modern cybersecurity threats requires a next-generation firewall. NGFWs incorporate many features beyond the core functionality of a firewall, enabling them to identify and block a greater range of subtle and sophisticated cybersecurity threats.
For more information about what to look for in an NGFW and how to make the best choice for your organization, check out this NGFW buyer’s guide.
Check Point has long been a leader in the network firewall space and offers industry-leading AI-powered firewall solutions. To learn more about the capabilities of Check Point Quantum Force NGFW, sign up for a free demo.
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