A firewall is a security control that monitors and filters network traffic according to defined rules. It helps reduce unauthorised access, limit exposure to threats, and enforce how users and systems communicate.
What a Firewall Does
- Allows trusted traffic and blocks unwanted connections.
- Segments networks so that sensitive systems are separated.
- Logs activity for monitoring and incident investigation.
- Can provide features such as VPN access, application control, and intrusion prevention.
Good Firewall Practices
Use a default-deny approach where appropriate, allow only the services that are required, document every rule, and remove rules that are no longer needed. Review logs and update firmware regularly.
Firewalls work best alongside strong passwords, patching, endpoint security, and user awareness.