network

IPplan is a free opensource IP Address management application. IPPlan is a web based IP address management software and tracking tool simplifying the administration of your IP address space. IPplan goes beyond IP address management including DNS administration, configuration file management, circuit management and storing of hardware information.

ntop is a free opensource network traffic probe that shows the network usage. ntop is based on libpcap and can run on Linux/Unix and Windows operating system. ntop provides a very easy to use a web access to navigate through ntop traffic information and get a dump of the network status.

IPTraf is a console-based network statistics utility for Linux. It gathers a variety of figures such as TCP connection packet and byte counts, interface statistics and activity indicators, TCP/UDP traffic breakdowns, and LAN station packet and byte counts. IPTraf is an IP traffic monitor that shows information on the IP traffic passing over your network.

Along with mii-tool, mii-diag and ethtool for NIC diagnostics... the NIC (NIC Information Collector) script collects network information necessary to investigate network related problems.