Web site: http://www.ntop.org
ntop is a popular network usage and protocol analyzer. It has two modes of operation: interactive (text-only) and Web mode, in which a Web browser is used to interact with ntop. In Web mode, ntop presents a neat and easy-to-use frames-based interface whereby statistics can be viewed by protocol type, traffic, source or destination address, throughput, and so on. ntop has the following command-line options:
[-r <refresh time (interactive = 3 sec/web = 120 sec)>] [-f <traffic dump file (see tcpdump)>] [-n (numeric IP addresses (interactive mode only))] [-p <IP protocols to monitor> (see man page)] ...