Top 10 free open source tools for network admins

From troubleshooting DNS queries and misbehaving network apps to keeping your configurations and passwords organized, these tools have you covered

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Top free open source tools for network admins: PHP Weathermap

Sometimes you want the 10,000-foot overview of your network traffic. PHP Weathermap provides exactly that. It shows a logical map of your routers and the links between them, using different colors to indicate how busy each link is. PHP Weathermap is a good complement to an application such as Cacti or OpenNMS.

PHP Weathermap does not handle its own data collection, so you'll need to pair it with another application such as Cacti, OpenNMS, MRTG, or RRDtool. PHP Weathermap has a plug-in that helps it integrate into Cacti, with some options available in the Cacti preference panels.

You will need to edit the map config files to adjust the appearance of your maps. You can do this by hand, though PHP Weathermap offers a GUI editor that runs within a Web browser. You can use the editor to create your nodes (routers and switches) and links, as well as produce a functioning map.

When you're ready for manual tweaking, you can add custom background images to the map and insert custom icons for your routers. You can also add subnodes, which allow you to display more information within the router's icon, such as CPU or memory usage. You can also insert parallel links or bonded links between routers.

Through further tweaking of config files, you can fine-tune the placement of router icons and the map's legend. If you have a more complicated map with plenty of router icons, you can create curved link lines between your router icons to help keep the map readable and less cluttered or cramped.

Top free open source tools for network admins: Ntop

Need an sFlow or NetFlow collector to get a thorough look at your data traffic flows? Ntop will take NetFlow or sFlow data from popular switches and routers and display it in a Web GUI, complete with clickable links that take you to details about particular hosts or protocols or to actual conversations and flows.

There are interesting features to Ntop's output, such as identifying workstation users by their email addresses and (passively) detecting the operating systems of network hosts through packet analysis. Ntop will break down traffic volume on a per-protocol basis, helpful for comparing the traffic your network actually has to what you think it should have.

Ntop can give you a list of IP protocols, sortable by protocol type, as well as lists of traffic sources and destinations. Ntop also creates a matrix table of IP traffic, so you can see who is talking to whom and how much data is being passed between the two. Of course, data is not as useful if you cannot sort it. Ntop allows you to sort on both the traffic source and the destination.

Platforms supported include Windows and all major Unix types, such as Linux, the BSDs, Solaris, and Mac OS X. Although resource usage will vary by network size and the configuration options that you choose, Ntop should be very light on modern workstation and laptop hardware. Ntop's Web UI accepts multiple HTTP usernames and passwords, so each member of your NOC team can have individual access, and you can force Ntop to work with HTTPS.

Ntop supports a wide range of network protocol types, IP protocol types, and even network media types. There is support for several VoIP protocols, including Cisco SCCP, Asterisk's IAX protocol, and of course SIP. Ntop can even do protocol decodes on most common IP protocols. If you want the information for later retrieval and analysis, Ntop can record its network traffic data to RRD-style files on a disk.

This article, "Top 10 free open source tools for network admins," was originally published at Follow the latest developments in networking and open source at For the latest business technology news, follow on Twitter.

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