Network Security

Network security starts with knowing your own environment, and the OSI model gives you a practical way to map it.

Key concepts

• The OSI model splits networking into seven layers, from physical cabling up to applications. Each layer carries its own weaknesses. Attacks can target any of them.
• You cannot defend what you have never inventoried. Keep a current list of your devices, connections, and exposed services. Forgotten devices are common on older networks.
• Segmentation divides your network into zones so one compromised device cannot reach everything. Keep guest traffic away from production systems. Limit which systems can talk to each other.
• Firewall and access rules should deny by default and permit only what is needed. Temporary rules often outlive the reason they were added.
• Encrypt traffic that crosses untrusted networks, and retire old protocols that send credentials in clear text. Weak wireless encryption deserves the same scrutiny.

Why it matters for your business

Your network connects nearly everything of value, so a single weak path can expose systems far from where an intruder first landed. Mapping your layers makes gaps visible and gives your technical and business teams a shared vocabulary for fixing them. Penetration testing then shows how those defenses actually hold up against realistic attack attempts rather than assumptions.