Nets is a flexible and extensible network inventory and asset management system that works on all Unix and Windows platforms, and works with most SQL databases. Its complete GUI allows you to maintain details of your entire network, from network links down to interfaces and routers. It assists in provisioning, costing, reporting, and maintaining network details. It includes a network browser, an extension API, and plugins for IP address map visualisation, reports, schematics.
ngrep strives to provide most of GNU grep's common features, applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes IPv4/6, TCP, UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP, FDDI, Token Ring, and null interfaces, and understands BPF filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.
ntopmg is a network probe that shows network usage in a way similar to what top does for processes. It acts as a Web server, creating an HTML dump of the network status. It sports a flow collector, an HTTP-based client interface for creating ntop-centric monitoring applications, and RRD for persistently storing traffic statistics. Its C++ core can be scripted in Lua, for changing the appearance and extending functionality.
Report Magic is an add-on for Analog, a Web site logfile analysis program. Generated reports include a description with tabulated, graphed, and summarized results. All colors, fonts, and background images are completely customizable to help make resulting reports fit the theme of your Web site. Report Magic has translations for several languages. It runs on any platform that will run Perl and pre-compiled versions are available for Win32 and Mac.
Snort is a network intrusion detection and prevention system. It is the most widely deployed technology of its kind in the world. It performs detection using a variety of methods including rules-based detection, anomaly detection, and heuristic analysis of network traffic. Its rules language is open source and available to the public as well.
Spong is a simple system-monitoring package. It features client-based monitoring (CPU, disk, processes, logs, etc.), monitoring of network services, grouping of hosts (routers, servers, workstations, and PCs), host-specific contact and downtime information, configuration on a client-by-client basis, results displayed via the Web, history of problems, messaging (via email or pager) when problems occur, and verbose information to help diagnosis problems. It communicates via simple TCP-based messages, and is written in Perl.
SysOrb is a client/server package that can monitor servers remotely (such as Web servers), or monitor devices on servers (such as disks, memory, load, etc.). It will alert the administrators via e-mail or pager if a server is entering a critical condition, and has its own database backend, allowing for massive collection of system statistics.