How to Monitor Network Traffic in htop?

This article provides a quick overview and practical guide on how to monitor network-related process statistics using the htop interactive process viewer in Linux. While traditionally focused on CPU, memory, and disk I/O, newer versions of htop support real-time network usage tracking per process. You will learn how to check if your version supports this feature, how to enable the relevant network columns, and how to interpret the data to identify bandwidth-hogging applications.

Checking for Network Monitoring Support

Not all versions of htop include network statistics out of the box. This functionality relies on htop being compiled with delay accounting support (via the Linux kernel’s taskstats) or specific network monitoring patches.

To check if your version supports it, open htop by typing htop in your terminal, and press F2 (or S) to enter the Setup menu. Navigate to the Columns section. If you can find columns named NET_RX (Network Received) and NET_TX (Network Transmitted) under the “Available Columns” list, your version supports network monitoring.

Enabling Network Columns in htop

If your system supports it, you must manually add the network columns to your main display. Follow these steps to configure your view:

1. Open htop in your terminal.
2. Press F2 to open the Setup menu.
3. Use the arrow keys to select Columns in the “Setup” left-hand pane.
4. Move to the “Available Columns” right-hand pane and scroll down until you find NET_RX and NET_TX.
5. Press F5 (or Enter depending on your version) on each to add them to your “Active Columns” list.
6. In the “Active Columns” pane, use F7 (Move Up) or F8 (Move Down) to position the network columns where you want them to appear on your screen.
7. Press F10 to save your changes and return to the main process list.

Interpreting Network Process Statistics

Once enabled, two new columns will appear in your htop interface:

• NET_RX: Displays the rate of data the process is actively receiving (downloading) over the network.
• NET_TX: Displays the rate of data the process is actively transmitting (uploading) over the network.

These values fluctuate in real-time, matching the update interval of your htop screen. To easily spot which application is draining your bandwidth, you can click on the NET_RX or NET_TX column headers to sort all running processes by their network activity.

Alternative Solutions for Older htop Versions

If your version of htop does not feature these columns, the underlying Linux kernel or the specific package build lacks the required patches. In such scenarios, you can use dedicated network process monitoring tools alongside htop. Command-line utilities like nethogs group network traffic by process PID, while iftop monitors overall bandwidth usage by interface, serving as excellent companions to a standard htop setup.