What is a firewall?
A firewall controls which network traffic is allowed or blocked between systems, networks, or the internet.
Simple example
A business firewall allows web browsing and email but blocks unexpected inbound connections from the internet.
Why it matters
Firewalls help reduce exposure, but they need proper rules and regular review.
Common warning signs
- The activity is unexpected or unusual for the business context.
- The request or system behaviour creates pressure to act quickly.
- Normal approval, verification, or security processes are bypassed.
- There are signs of unauthorised access, data exposure, or system change.
- Staff are unsure whether the request, message, or system behaviour is legitimate.
Cyber Doc view
This term should be understood in business context, not only as a technical issue. Good protection usually combines clear processes, appropriate technical controls, staff awareness, and a calm response plan.
What to do
Proactive steps
- Keep firewall rules simple and documented.
- Block unnecessary inbound access.
- Review rules regularly.
- Use VPN or secure access methods for remote administration.
- Log and monitor important firewall events.
Reactive steps
- Review recent firewall changes and logs.
- Block suspicious traffic if an attack is underway.
- Confirm whether exposed services were accessed.
- Update rules to close unnecessary access.
- Preserve logs for investigation.
Related terms
- Network segmentation
- Attack surface
- VPN