# Top 7 Free Network Monitoring Tools for IT Admins
[Download PDF](https://www.manageengine.com/network-monitoring/Network-Monitoring-Software.pdf)
## Table of contents
- [Introduction](https://www.manageengine.com/network-monitoring/free-network-monitoring-tools-wp.html#summary)
- [Critical network elements that need monitoring](https://www.manageengine.com/network-monitoring/free-network-monitoring-tools-wp.html#seven)
- [Top network management requirements for IT admins](https://www.manageengine.com/network-monitoring/free-network-monitoring-tools-wp.html#three)
- [Freeware: Commercial free network monitoring software](https://www.manageengine.com/network-monitoring/free-network-monitoring-tools-wp.html#freeware)
- [Integrated yet affordable IT management solutions from ManageEngine](https://www.manageengine.com/network-monitoring/free-network-monitoring-tools-wp.html#mengine)
## Introduction
Networks are becoming critical components of business success - irrespective of whether you are small or BIG. When network fails, customers and employees cannot communicate, employees cannot access critical information or use basic print or email services, resulting in productivity loss and revenue loss. [Network monitoring tools](https://www.manageengine.com/network-monitoring/network-monitoring-tools.html) reduce network outages and allow businesses to operate more fluently, cut costs, and prevent revenue loss. And for those who are small and are not allowed to think of a budget for a network monitoring software, a better alternative is to start with opencsource and freeware tools that reduce the time and money spent on network administration and management. This paper talks about the top freeware and open source network monitoring software available today.
## Critical network elements that need monitoring
Businesses depending on their size buy various networking infrastructure elements. Some of the basic network elements that need continuous monitoring are:
**Email servers**: Every organization will have an Email server which distributes emails to all LAN users. If the email server fails, users are disconnected from the external world and key functions such as customer support takes a hit. IT Managers need to monitor their email servers for availability, mails in queue, size of mails received etc.
**WAN links**: Small Enterprises can save money by optimizing the WAN links. If over subscribed, it costs heavily and if under subscribed it chokes the network. Hence IT administrators should carefully balance the throughput, committed information rate (CIR) and burst rate with congestion, response time, and discards to optimize the link utilization. IT Managers should also find out who’s using the most bandwidth to make necessary arrangements. Apart from bandwidth monitoring (discussed above), routers need to be monitored for availability and performance periodically. If a router fails it halts the entire LAN and hence IT Managers should set thresholds on various parameters on routers and attend problems immediately.
## Business applications
- **Servers & Services**: Servers run critical applications and hence should be monitored for CPU, memory, disc space, services running on them (FTP, DNS, ECHO, IMAP, LDAP, TELNET, HTTP, POP, etc.) and their response time. Moreover the traffic utilization trends of these servers should also be monitored.
- **Server logs**: Small businesses running windows machines should also monitor the server logs for failed logon, account lockouts, bad passwords, failed attempts to secure files, security log tampering etc. Monitoring these logs gives clear picture of security loop holes existing inside the organization.
- **Applications, Databases, & Websites**: Small businesses run several mission critical applications, websites, and databases which need to be monitored periodically. Applications can be monitored for availability, response time etc. URLs should be monitored for availability.
- **LAN Infrastructure**: Your LAN infrastructure devices such as switches, printers & wireless devices.
## Top network management requirements for IT admins
Small businesses have different network management needs and expectation because technical expertise and staff are limited. They want tools that are low cost, easy to install and use, and feature rich.
- **Low cost**: The network monitoring tool should be affordable.
- **Easy to install and use**: The network monitoring tool should be intuitive enough to get started without reading that dry boring documentation.
- **Feature rich**: Over and above, a [nework monitor](https://www.manageengine.com/network-monitoring/network-monitor.html?freenetmontools) should be able to monitor all your resources - both what you have today as well as what you might have tomorrow.
## 1) Nagios: The open source network monitoring software
Nagios® is a host and service monitor designed to run under the Linux operating system, but works fine under most *NIX variants as well. The monitoring daemon runs intermittent checks on hosts and services you specify using external "plugins" which return status information to Nagios. When problems are encountered, the daemon can send notifications out to administrative contacts in a variety of different ways (email, instant message, SMS, etc.). Current status information, historical logs, and reports can all be accessed via a web browser.

## 2) MRTG: The open source traffic monitoring software
The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network links. MRTG generates HTML pages containing PNG images which provide a LIVE visual representation of this traffic like this:

## 3) Kismet: The open source wireless discovery / intrusion prevention software
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.
Kismet identifies networks by passively collecting packets and detecting standard named networks, detecting (and given time, de-cloaking) hidden networks, and inferring the presence of non-beaconing networks via data traffic.

## Other open source tools that are worth giving a try:
| Network Management | Others |
|---|---|
| **Network Management**