How to use the command nethogs (with examples)

NetHogs is a command-line tool that allows you to monitor the bandwidth usage per process on your Linux system. It provides real-time information about the processes and programs that are using your network resources. This can be useful for troubleshooting network performance issues, identifying bandwidth-hungry applications, and optimizing network usage.

Use case 1: Start NetHogs as root (default device is eth0)

Code:

sudo nethogs

Motivation: Starting NetHogs as root allows you to monitor the network usage of all processes running on your system. This can help you identify any processes that are using excessive bandwidth and taking up network resources.

Explanation:

• sudo: Runs the command as superuser (root) to ensure access to network data.
• nethogs: The command itself.
• No device argument: By default, NetHogs monitors the eth0 network device.

Example output:

Refreshing: 2
NetHogs version 0.8.5-1

  PID USER     PROGRAM                      DEV        SENT      RECEIVED       
 1001 john     chrome                      eth0       1.23MB     4.56MB
 2002 jane     firefox                     eth0       0.83MB     2.37MB
 3003 alice    spotify                     eth0       0.12MB     0.03MB

In this example, NetHogs is monitoring the eth0 network device. It displays the PID (Process ID), USER (username), PROGRAM (name of the program/process), DEV (network device), and the amount of data SENT and RECEIVED by each process. The output is refreshed every 2 seconds.

Use case 2: Monitor bandwidth on specific device

Code:

sudo nethogs device

Motivation: Sometimes, you may have multiple network devices on your system, and you want to monitor the bandwidth usage on a specific device. By specifying the device, you can focus on the network activity happening through that device.

Explanation:

• sudo: Runs the command as superuser (root) to ensure access to network data.
• nethogs: The command itself.
• device: Specifies the network device you want to monitor (e.g., eth0, wlan0).

Example output:

Refreshing: 2
NetHogs version 0.8.5-1

  PID USER     PROGRAM                      DEV        SENT      RECEIVED       
 1001 john     chrome                      eth0       1.23MB     4.56MB
 2002 jane     firefox                     eth0       0.83MB     2.37MB

In this example, NetHogs is monitoring the network activity specifically on the eth0 device. It displays the same information as before but only for the processes using that particular device.

Use case 3: Monitor bandwidth on multiple devices

Code:

sudo nethogs device1 device2

Motivation: In complex network setups, you may want to monitor the bandwidth usage on multiple devices simultaneously. By specifying multiple devices, you can get an overview of the network activity happening across different interfaces.

Explanation:

• sudo: Runs the command as superuser (root) to ensure access to network data.
• nethogs: The command itself.
• device1 device2: Specifies the multiple network devices you want to monitor (e.g., eth0, wlan0).

Example output:

Refreshing: 2
NetHogs version 0.8.5-1

  PID USER     PROGRAM                      DEV        SENT      RECEIVED       
 1001 john     chrome                      eth0       1.23MB     4.56MB
 2002 jane     firefox                     eth0       0.83MB     2.37MB
 3003 alice    spotify                     wlan0      0.12MB     0.03MB
 4004 bob      ssh                         wlan0      0.01MB     0.01MB

In this example, NetHogs is monitoring the network activity on both the eth0 and wlan0 devices. It displays the same information as before but for processes using different devices.

Use case 4: Specify refresh rate

Code:

sudo nethogs -t seconds

Motivation: Changing the refresh rate allows you to control how frequently NetHogs updates the bandwidth usage information. This can be helpful if you want more or less frequent updates, depending on your specific monitoring needs.

Explanation:

• sudo: Runs the command as superuser (root) to ensure access to network data.
• nethogs: The command itself.
• -t seconds: Specifies the refresh rate in seconds (e.g., 5, 10).

Example output:

Refreshing: 5
NetHogs version 0.8.5-1

  PID USER     PROGRAM                      DEV        SENT      RECEIVED       
 1001 john     chrome                      eth0       1.23MB     4.56MB
 2002 jane     firefox                     eth0       0.83MB     2.37MB

In this example, NetHogs is monitoring the network activity with a refresh rate of 5 seconds. The output is updated every 5 seconds, providing a real-time view of the bandwidth usage per process.

Conclusion:

NetHogs is a powerful command-line tool for monitoring bandwidth usage per process. By using the various options and arguments, you can customize the monitoring experience to suit your needs. Whether you want to identify bandwidth-hogging applications, optimize network usage, or troubleshoot network performance issues, NetHogs provides the information you need to analyze and manage network activity effectively.