Network firewalls are one of the oldest and most effective mechanisms for protecting computer networks.
Their task is to monitor and control traffic between the internal network (e.g., corporate) and the external one (e.g., the Internet).
It is the firewall that decides which connections are safe and which should be blocked.
What Are Network Firewalls?
Network firewalls are security systems that analyse network traffic and decide whether data can pass through.
They protect against unauthorised access, attacks, and malicious software.
Without a network firewall, every network would be like an open door for cybercriminals.
How Network Firewalls Work
A firewall analyses both incoming and outgoing traffic:
it compares it against predefined security rules and then blocks or allows data packets.
This enables:
- blocking unauthorised connection attempts,
- filtering dangerous packets,
- maintaining data integrity and confidentiality.
Types of Network Firewalls
Depending on the method of operation and application, we distinguish:
- Hardware firewalls – physical devices installed at the network perimeter.
- Software firewalls – applications installed on servers or endpoints.
- Cloud-based firewalls – services provided by cloud providers (e.g., AWS WAF, Azure Firewall).
- Next-Generation Firewalls (NGFW) – integrate traditional functions with advanced features like IDS/IPS and application control.
Functions of Firewalls
- Packet filtering – analysing headers and deciding on traffic flow.
- Application control – monitoring and blocking specific apps or protocols.
- VPN support – enabling secure remote connections.
- Logging and reporting – recording events for later analysis.
Protection Against Threats
Firewalls effectively protect against:
- Unauthorised access – blocking intrusion attempts.
- Malicious software – stopping viruses and trojans at the network boundary.
- DDoS attacks – protecting against overload and service paralysis.
Without an effective network firewall, your network is exposed to uncontrolled traffic and external attacks.
Firewall Configuration
For a firewall to work effectively, it requires proper configuration:
- Define security rules – establish which connections are allowed.
- Monitor logs and events – analyse detected incidents.
- Regularly update software – remove known vulnerabilities.
- Test effectiveness – conduct periodic audits and penetration tests.
Best Practices
- Regular software updates for the firewall.
- IT team education – knowledge of configuration principles and incident response.
- Configuration backups – to quickly restore the system after a failure.
Examples of Firewall Applications
- Companies – protection of IT infrastructure and customer data.
- Homes – securing Wi-Fi routers and IoT devices.
- Government institutions – protection of sensitive data and critical systems.
Summary
Network firewalls are a key element of any cybersecurity strategy.
Their effectiveness depends on configuration, regular updates, and user awareness.
A firewall is not just technology — it’s daily protection of your organisation’s digital boundaries.
Get in Touch
Need help with auditing or configuring a network firewall?
Email: biuro@wichran.pl
Phone: +48 515 601 621
Author: Piotr Wichrań – Court-appointed IT forensic expert, IT/OT cybersecurity specialist, licensed private investigator
@Informatyka.Sledcza