Passive-Network-Scan-L2/3 is a lightweight, passive network discovery tool that listens on a network interface
in promiscuous mode and collects Layer 2 and Layer 3 signalling (ARP, STP, DHCP,
mDNS, SSDP). It aggregates discovered hosts by MAC address, attempts to
measure passive RTTs for request/response protocols, maintains per-protocol RTT
histories and simple service hints, and can emit structured events and a final
table in JSON or CSV formats.