LAN protection revolves around Layer-2 protection on OSI models. All layers of TCP/IP have got its own security threats and vulnerabilities. A firewall is one very simple way to protect a LAN, but this only protects traffic which is coming from outside. Layer-2 attacks are sources from inside a LAN.
It is difficult for an outsider to achieve a Layer-2 attack, but never underestimate the power of insiders. Insiders can do more damage than outsiders by launching malicious attacks from inside the network. The proactive deterrence for this would be to keep track of your logs and setup your IDS to detect such attacks!
Before going deeper into this topic, let's get an understanding of how network switches ...