pmacct is a network tool to gather IP traffic information (bytes counter and
number of packets). Aggregation of statistics is done either by looking at
destination, source, both source and destination, or unidirectional IP flows.
Data is stored in an in-memory table or using an SQL database (currently only
MySQL). The content of these tables can be later retrieved by a client program
via a local stream-oriented connection (for simple output or export to MRTG) or
via an SQL client. Gathering packets off the wire is done with the pcap library
and promiscuous mode of one or more network interfaces.

WWW: http://www.ba.cnr.it/~paolo/pmacct/