Reader favorites: 10 great free network tools

There is nothing magic about ZipTie. It is, at the core, a nice front end to communication protocols (SNMP, Secure Shell (SSH), Telnet, HTTP, Trivial File Transfer Protocol and so on). But it uses those, and other protocols, to discover and consolidate information on network devices. Do you manage your network devices with HTTP running on a nonstandard port? No problem; just create another protocol entry and specify the desired port.

One drawback is that ZipTie only supports a small number of network vendors in its core release. However, being open source, a large and growing database of user-submitted add-on modules extends the functionality of ZipTie significantly. These add-ons provide SNMP Management Information Base (MIB) data so that ZipTie can recognize the devices.

Installing ZipTie is somewhat more complicated than installing some of the other reviewed tools. Read the prerequisites page before downloading and installing. Links are provided for the Sun Java Development Kit and Perl for the server, and Sun Java Runtime for the client. Install these first. Be sure to change the default administrator password before using it on your production network. It's not intuitive how to do so but read the documentation; it requires that a command be run at the command line interface on the server.

ZipTie does operate in a true client/server model, so you can allow one source for your configuration management and still have multiple clients manage it via the client piece. It's definitely worth looking into. If a particular module doesn't exist for one of your network devices, consider submitting a module yourself. That is after all the backbone of open source.

NetStumbler

If you manage wireless networks and have never used NetStumbler, you need to. NetStumbler is, at the core, an interface between what your 802.11 wireless card "sees" and what you see. It presents all of the wireless networks found in different formats, including individual transmitter signal strength or aggregate information grouped by Service Set Identifier channel or whether the network is secured or "open."

NetStumbler is the de facto tool for war drivers, as it easily identifies networks within range of a client. War drivers look for open wireless networks, and a corporate network that has improperly configured and/or installed wireless access points is ripe for exploitation. NetStumbler is a cheap tool for conducting surveys to find these potential network entry points.

What about strength of signal surveys? Do you have one of those "regular" help desk callers who insists that the wireless network always becomes hard to use at a certain time of day? Take a laptop with NetStumbler and let it run unattended (in a secured location, of course) on site. You'll have a real-time log of signal strength data for troubleshooting. At least you can conclusively show if there is a drop in your access point's signal -- or a drop in connectivity from interference associated with that 2:30 p.m. nuking of a burrito in the local (and leaky) microwave.

There's a reason why NetStumbler has been around for so long. It works, and it's useful. Anyone who manages a wireless network, or even those looking for a Wi-Fi hot spot, needs NetStumbler.