Netdisco is an Open Source web-based network management tool.

Designed for moderate to large networks, configuration information and
connection data for network devices are retrieved by SNMP. With Netdisco you
can locate the switch port of an end-user system by IP or MAC address. Data is
stored using a SQL database for scalability and speed.
Cisco Discovery Protocol (CDP) optionally provides automatic discovery of the
network topology. The network is inventoried by both device model and operating
system (like IOS). Netdisco uses router ARP tables and L2 switch MAC forwarding
tables to locate nodes on physical ports and track them by their IP addresses.
For each node, a time stamped history of the ports it has visited and the IP
addresses it has used is maintained. Netdisco gets all its data, including CDP
topology information, with SNMP polls and DNS queries. It does not use CLI
access and has no need for privilege passwords. Security features include a
wire-side Wireless Access Point (AP) locator.