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How to set a system wide bandwidth limit on Linux systems

Written by Solène, on 06 February 2021.
Tags: #linux #bandwidth

Comments on Fediverse/Mastodon

In these times of remote work / home office, you may have a limited bandwidth shared with other people/device. All software doesn't provide a way to limit bandwidth usage (package manager, Youtube videos player etc...).

Fortunately, Linux has a very nice program very easy to use to limit your bandwidth in one command. This program is « Wondershaper » and is using the Linux QoS framework that is usually manipulated with "tc", but it makes it VERY easy to set limits.

What are QoS, TC and Filters on Linux

On most distributions, wondershaper will be available as a package with its own name. I found a few distributions that didn't provide it (NixOS at least), and some are providing various wondershaper versions.

To know if you have the newer version, a "wondershaper --help" may provide information about "-d" and "-u" flags, the older version doesn't have this.

Wondershaper requires the download and upload bandwidths to be set in kb/s (kilo bits per second, not kilo bytes). I personally only know my bandwidth in kB/s which is a 1/8 of its kb/s equivalent. My home connection is 1600 kB/s max in download and 95 kB/s max in upload, I can use wondershaper to limit to 1000 / 50 so it won't affect much my other devices on my network.

# my network device is enp3s0
# new wondershaper
sudo wondershaper -a enp3s0 -d $(( 1000 * 8 )) -u $(( 50 * 8 ))

# old wondershaper
sudo wondershaper enp3s0 $(( 1000 * 8 )) $(( 50 * 8 ))

I use a multiplication to convert from kB/s to kb/s and still keep the command understandable to me. Once a limit is set, wondershaper can be used to clear the limit to get full bandwidth available again.

# new wondershaper
sudo wondershaper -c -a enp3s0

# old wondershaper
sudo wondershaper clear enp3s0

There are so many programs that doesn't allow to limit download/upload speeds, wondershaper effectiveness and ease of use are a blessing.