Computerworld recently showcased 10 great free network management tools. Readers responded with some of their own favorites, so I'm going to take a look at those tools and report on their capabilities and usage from my perspective as an experienced network manager.
But first, let's address security. Readers mentioned the possible security implications of downloading free tools, which is a valid concern. What's to stop a coder from producing a neat network administration tool that secretly sends information about your network to a collection point for exploitation at a later date?
That's why it's a good idea to only download applications from valid sites -- such as SnapFiles.com and Download.com -- that tests applications before releasing them -- or from open-source sites such as SourceForge.net. Sometimes, such as in the case of Multi Router Traffic Grapher, the application is so widely used that it can be assumed that it's safe simply by virtue of its popularity; if the tool had a problem, someone would have found it.
No matter what, never install an application that has the ability to cut into and examine your network without understanding what it does and doesn't do. Some applications ask you to enter an administrative username and password or a Simple Network Management Protocol (SNMP) community name so they can probe deeper into certain devices. Others aggressively scan the network to the point where security devices -- and other administrators -- may detect the scan as an attack. Try these in a safe environment (test network or DMZ) and use a free sniffer like Wireshark to verify what the application is doing before deploying it in a production environment.
Also, some readers noted that "freeware" applications aren't always completely free. Some applications are open source and designed as part of a greater good, which elicits input from users to make the applications better. In the case of ZipTie, that would mean plug-ins for currently unsupported network equipment. Other freeware applications are self supporting via ad sales. Other freeware vendors hope that if you like their free version you'll purchase the "platinum" version with bells and whistles and the ability to slice bread.
So with those caveats in mind, let's take a look at readers' favorite free network tools.
Note that I only include Windows tools. Some readers suggested Linux tools, but not everyone can afford the time to learn Linux just to evaluate a useful tool. Also, some of these tools, such as Nessus, can run on both Linux and other operating systems. And if you're really into Linux, you can read my previous article "Linux primer for networkers".