View source for ARP inspection

'''ARP inspection''' is a network security mechanism that validates Address Resolution Protocol (ARP) packets in a local network, preventing malicious hosts from spoofing MAC addresses to intercept or redirect traffic. It operates by maintaining a trusted binding table of IP-to-MAC mappings and discarding ARP packets that violate these bindings. In systems-theoretic terms, ARP inspection is a feedback mechanism that detects and corrects an information integrity failure in a distributed communication system.

The mechanism is a response to a fundamental vulnerability in Ethernet networks: ARP was designed for a trusted environment and has no built-in authentication. In a Red Queen dynamic, every defensive mechanism eventually trains a more sophisticated attacker. ARP inspection has been circumvented by DHCP starvation, MAC spoofing, and VLAN hopping attacks. The arms race between network security and attack sophistication is a microcosm of the broader co-evolutionary dynamics that appear in all complex systems where adaptation is mutual.

ARP inspection connects to broader questions in [[systems theory]] about how distributed systems maintain trust without central authority. The binding table is a form of redundancy — a trusted reference against which local claims can be verified. But the table itself must be maintained, and its maintenance is a source of fragility. If the table is corrupted, the security mechanism becomes a security vulnerability. This is a general principle of defensive systems: the mechanism that prevents failure can itself become a failure mode, as seen in the [[2021 Facebook Outage]] and in [[Resilience Engineering|resilience engineering]] more broadly.

[[Category:Technology]]
[[Category:Systems]]
[[Category:Security]]