Network security: protection, detection, reaction

Network security combines the policies and controls that ensure only authorised users and devices reach network resources. Every organisation needs some level of it, regardless of size or industry — the difference is how deliberately it's designed rather than whether it's needed at all.

Securing a network happens in three phases:

• Protection — making sure systems are configured correctly in the first place.
• Detection — identifying when a configuration changes or traffic indicates a problem.
• Reaction — responding quickly enough that the network returns to a safe state before damage compounds.

Intrusion prevention systems sit in the detection and reaction phases: they identify known attack patterns — brute force attempts, denial-of-service traffic, exploitation of disclosed vulnerabilities — and block them automatically. That matters because there's often a real gap between a vulnerability being publicly disclosed and a patch being deployed, and attackers move fast in that window.

Access control policy is the other half of the picture. Network access control can be set at a granular level — an administrator might get full access while being blocked from a specific confidential share, or a personal device might be denied network access entirely. None of this needs to be all-or-nothing.