IT Management Tools

• Nagios is an open source host, service and network monitoring program.
• JFFNMS is a Network Management and Monitoring System designed to monitor a IP SNMP / Syslog / Tacacs+ Network. It can be used to monitor any standards compilant SNMP device, Server, Router, TCP port or anything you want, if you write a custom poller, we also provide some Cisco focused features.
  
• OpenNMS is the world's 1st Enterprise grade Network Management Platform developed under the open-source model.
• Big Sister, Network and System Monitor.
• Netdisco is an Open Source web-based network management tool.
• ZABBIX is software for monitoring of your applications, network and servers. ZABBIX supports both polling and trapping techniques to collect data from monitored hosts. A flexible notification mechanism allows easy and quckly configure different types of notifications for pre-defined events.
• The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network-links.
• ntop is a network traffic probe that shows the network usage, similar to what the popular top Unix command does. ntop is based on libpcap and it has been written in a portable way in order to virtually run on every Unix platform and on Win32 as well.
• syslog-ng is the world's most flexible and scalable audit trail processing tool for organizations of any size. It provides a centralised, securely stored log of all devices on your network, whatever platform they run on. And syslog-ng also incorporates a host of powerful features, including filtering based on message content, as well as customisable data mining and analysis capabilities. syslog-ng comes as part of the Zorp product line or can be downloaded as a drop-in replacement for stock UNIX system logging software.
  
• RRD is the Acronym for Round Robin Database. RRD is a system to store and display time-series data (i.e. network bandwidth, machine-room temperature, server load average). It stores the data in a very compact way that will not expand over time, and it can create beautiful graphs. It can be used via simple shell scripts or as a perl module.
• Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense for LAN-sized installations up to complex networks with hundreds of devices.
• Nmap ("Network Mapper") is a free open source utility for network exploration or security auditing. It was designed to rapidly scan large networks, although it works fine against single hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. Nmap runs on most types of computers and both console and graphical versions are available.
• NeDI, a web based network discovery & management system.
• Nessus is the world's most popular open-source vulnerability scanner used in over 75,000 organizations world-wide. Many of the world's largest organizations are realizing significant cost savings by using Nessus to audit business-critical enterprise devices and applications.
• Snort is an open source network intrusion prevention system, capable of performing real-time traffic analysis and packet logging on IP networks. It can perform protocol analysis, content searching/matching and can be used to detect a variety of attacks and probes, such as buffer overflows, stealth port scans, CGI attacks, SMB probes, OS fingerprinting attempts, and much more.
• Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system. Kismet will work with any wireless card which supports raw monitoring (rfmon) mode, and can sniff 802.11b, 802.11a, and 802.11g traffic.
• Webmin is a web-based interface for system administration for Unix. Using any browser that supports tables and forms (and Java for the File Manager module), you can setup user accounts, Apache, DNS, file sharing and so on.

More info here...