Tool

A distributed network monitor with trending.

An open source network monitor project written in C++.

God, written by Tom Preston-Werner, is a Ruby based network monitoring tool.

Zenmap Network Topology provides an interactive, animated visualization of the hosts on a network and connections between them.

ZABBIX is an enterprise-class open source distributed monitoring solution.

Nagios® is a comprehensive and fully featured host and service network problem monitoring system.

JFFNMS is a Network Management System designed to mantain a IP/SNMP/Syslog/ Tacacs+ Network but can also be used to monitor any standards compliant SNMP device, Server, TCP port, or Custom Poller. Supports some Cisco routers/switches.

Sysmon is a high performance, accurate network monitoring tool.

PIKT® is a cross-categorical toolkit for monitoring and configuring systems, organizing system security, formatting documents, assisting command-line work, and performing other common systems administration tasks.

Zenoss is an enterprise-grade open source monitoring platform. Zenoss products provide application, server, and network management capabilities built on the python-based Zope application server.

OpenNMS is a project that attempts to replicate an enterprise grade Network Management System (NMS) like HP OpenView. The software provides network and system monitoring, trouble ticketing, asset management and rudimentary network mapping.

A framework network management system. you can either use it stand alone or integrate with HP OpenView maps.

Another network management system on steroids. I doubt any SME is going to use BMC, but hey you never know.

I doubt many people haven’t heard of OpenView. It is debatable whether it is a SME tool but maybe some SMEs have very deep pockets.

Nemesis is a command-line network packet crafting and injection utility for UNIX-like and Windows systems built on top of NMap.

A range of products for traffic generation and network simulation.

A network appliance, based upon the Zenoss open source network management project, in an easy to deploy hardware form factor.

A plug and play appliance with good network mapping ability.

SNMPSTAT is network-monitoring system, designed to monitor standard network routers, switches and firewalls using SNMP

Big Sister monitors systems, tracks current status and status change history, and triggers alarms.

NodeWatch is a network monitoring polling tool. It logs connectivity changes and performs user defined commands.

Autostatus is a network and server monitoring program designed to support large complex networks.

RRDTool (Round Robin Database Tool) is a system to store, display and graph time-series data. Many open source network management tools are built upon the functionality provided by RRDTool.

HotSaNIC (Html overview to System and Network Information Center) consists of a set of perl-scripts built on Tobias Oetiker’s rrdtool to generate graphical system-statistics.

NRG is a system for maintaining and visualizing network data and other resource utilization data.

Torrus is designed to be the universal data series processing framework. Its scalable hierarchical design, application-independent core, and highly customizable architecture make Torrus an attractive choice both for small installations and for big enterprise or carrier networks.

RTG is a flexible, scalable, high-performance SNMP statistics monitoring system.

Cacti is a complete frontend to rrdtool, it stores all of the nessesary information to create graphs and populate them with data in a MySQL database. The frontend is completely PHP driven.

A commercial MRTG derivative, with all of the nice bits about MRTG but easy to install and configure.

A mature network monitor with an extensive range of server tests and a wide range of alerting options.

A web based network monitoring application running on Microsoft Windows. A distributed edition is available.

Wireshark, formerly called Ethereal, is a mature network protocol analyzer for many Unix platforms and Microsoft Windows. It allows you to examine data from a live network or from a capture file on disk.

A console based IP LAN monitor which can be combined with rrdtool to provide per protocol network

RANCID is a switch and router configuration management tool

A Visual Basic (VB) wrapper for the winpcap library.

An object oriented perl wrapper for the winpcap library.

A Java wrapper for both winpcap and libpcap programming libraries.

libpcap is a system-independent interface for user-level packet capture. libpcap provides a portable framework for low-level network monitoring. Applications include network statistics collection, security monitoring, network debugging, etc.

Packet Sniffer SDK (former Network Investigation Suite) is a Gigabit network compatible development suite for network packet capture in Windows OS family environment. Packet Sniffer SDK library set is 100% exactly what you knew you wanted but never expected to get: a fully self-contained, dynamically-loaded packet capture technology that is compatible with Microsoft Visual C++, Microsoft Visual Basic, Intel C++, Borland C++ Builder, Borland Delphi and many others.

The Solera DS Series is a suite of network packet recorder appliances with support up to the gigabit barrier. Solera Networks’ devices capture, archive, and regenerate network traffic data.

Kaboodle is a free, open-source Internet app which provides complete visualization of your LAN, updated in near-real time.

A network mapping tool with multi-level collaboration features. Don’t expect the website to actually tell you anything useful though, one of the worst cases of marketing bull I’ve seen in a while.