Local area network security is often neglected in favor of perimeter defenses — but an attacker who gains a foothold inside your network can move laterally to reach any system on the LAN. Here’s how to secure your LAN against both external attackers and insider threats.
Network Segmentation
Flat networks — where all systems can communicate freely — are extremely dangerous once an attacker gains access. Use VLANs to segment your network into logical zones: user workstations, servers, voice, management, guest access. Use ACLs or internal firewalls to restrict communication between segments to only what’s required.
Switch Security
Network switches have numerous security features that are often left at factory defaults. Enable port security to limit the number of MAC addresses per port, disable unused ports, enable DHCP snooping to prevent rogue DHCP servers, and enable Dynamic ARP Inspection (DAI) to prevent ARP poisoning attacks.
Authentication and Authorization
Implement 802.1X port-based authentication to require users and devices to authenticate before being granted network access. Combined with NAC, this provides a complete access control framework that covers both wired and wireless connections.