THREAT‑WATCH
Glossary
Firewall
A network security device or software that monitors and filters incoming and outgoing traffic based on defined security rules.
Firewalls sit at the boundary between trusted and untrusted networks (or between network segments) and block traffic that doesn't match allowed rules. Modern 'next-generation' firewalls go beyond basic port/protocol filtering to inspect traffic content, application behavior, and known threat signatures, but a firewall alone doesn't stop threats that arrive through allowed channels, like a phishing email or a compromised software update.