Out of the myriad of utilities that are available for Linux, top is a troubleshooting tool that often comes up in conversation. With good reason, top is a tool that many users frequently turn to. It is is a small open source utility that offers a dynamic real-time view of a running system, allowing users to monitor the processes that are running on a system, and to identify which applications are consuming more resources than they should. While top (and other alternatives) are useful tools to monitor the running processes on a system, functionality does not extend to network activity.

Monitoring processes is not, in itself, sufficient to ensure a smoothly running system. Network monitoring tools can help to identify issues before they escalate to emergency status. This type of software is not only useful for network administrators. Home users with a small network or even just a single computer will benefit from the software featured in this article.

The focus here is not to identify software that provides general system monitoring solutions. We covered the finest open source system monitoring tools in a previous Group Test. Instead, the purpose of this article is to identify small console based utilities that show network usage in a way reminiscent to what the top utility does for processes. Rather than borrowing code from top, the small tools here borrow ideas from that troubleshooting tool, such as providing instant real-time data about a system that updates as the situation changes. If you are looking for small tools to diagnose TCP and UDP connection issues in real time and other related issues, to help isolate the causes of network problems, and to monitor bandwidth that is being consumed by applications and users, the software featured in this article will be of interest. We particularly like IPTraf. Although it has not been updated in years, it remains an indispensable utility.

Now, let’s explore the 5 network ‘top’ tools at hand. For each title we have compiled its own portal page, a full description with an in-depth analysis of its features, a screenshot of the software in action, together with links to relevant resources and reviews.

Network 'top' Tools IPTraf Interactive Colourful IP LAN Monitor iftop Displays bandwidth usage on an interface by host NetHogs Groups bandwidth by process ntop Network traffic probe that shows the network usage jnettop Traffic visualiser, capturing traffic going through the host

Return to our complete collection of recommended free and open source software including our latest additions.

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