bcnu is a Web-based system management tool which delivers information on the status of networked systems in a simple and easy-to-use manner. It uses a web browser to display information about hosts in a tabular form. Historical information can be held indefinitely, and there is a powerful query tool available to interrogate it. Client systems can run an agent which logs information back to a central system. An agent scheduler is integrated to allow agents to be run at different intervals. Standard agents include ftp, http, disk space, logfiles, processes, and more.
Big Brother is a combination of monitoring methods. Unlike SNMP where information is just collected and devices polled, Big Brother is designed in such a way that each local system broadcasts its own information to a central location. Simultaneously, Big Brother also polls all networked systems from a central location. This creates a highly efficient and redundant method for proactive network monitoring.
Ettercap is a network sniffer/interceptor/logger for ethernet LANs. It supports active and passive dissection of many protocols (even ciphered ones, like SSH and HTTPS). Data injection in an established connection and filtering on the fly is also possible, keeping the connection synchronized. Many sniffing modes were implemented to give you a powerful and complete sniffing suite. Plugins are supported. It has the ability to check whether you are in a switched LAN or not, and to use OS fingerprints (active or passive) to let you know the geometry of the LAN.
GKrellM is a GTK-based stacked monitor program that charts SMP CPUs, disks, load, active net interfaces, and internet connections. There are also builtin monitors for memory and swap, file systems with mount/umount feature, mailbox checking including POP3 and IMAP, clock/calendar, laptop battery, sensors (temperatures, voltages, and fans), and uptime. It has LEDs for the net monitors and an on/off button and online timer for PPP. There is a GUI popup for configuration, plugin extensions can be installed, and many themes are available. It also features a client/server monitoring capability.
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.
The GNU Gatekeeper is a free H.323 gatekeeper based on the OpenH323 project. You can use it to manage a Voice-over-IP network and let endpoints (e.g., Netmeeting) communicate through symbolic names. It also has an external interface for billing and other applications. It runs on a number of Unix versions (including Linux and Solaris) and Windows.