Test Linux Network Speed with fast, speedtest, and iPerf

Network speed is a key performance metric for any operating system, and the following Linux command‑line tools let you quickly assess both download and upload rates.

fast (fast-cli)

fast

is a service provided by Netflix, available as a CLI and via the web at fast.com.

Install it globally with npm: $ npm install --global fast-cli Basic usage returns only the download speed:

$ fast
93 Mbps ↓

To include upload speed, add the -u flag:

$ fast -u
81 Mbps ↓ / 8.3 Mbps ↑

speedtest (speedtest-cli)

speedtest

is a widely used Python‑based tool. Install it via apt or pip:

$ sudo apt install speedtest-cli
# or
$ sudo pip3 install speedtest-cli

Run the command to see a full report of download and upload speeds, along with server selection details:

$ speedtest
Retrieving speedtest.net configuration...
Testing from Tencent cloud (140.143.139.14)...
Selecting best server based on ping...
Hosted by Henan CMCC 5G (Zhengzhou) [9.69 km]: 28.288 ms
Download: 56.20 Mbit/s
Upload: 1.03 Mbit/s

The output confirms both download and upload rates, making it suitable for scripting and periodic testing.

iPerf

iperf

is a versatile network performance tester that measures TCP and UDP bandwidth, latency, jitter, and packet loss. It works on Linux, macOS, and Windows.

Install on Debian‑based systems: $ sudo apt install iperf iPerf requires a server and a client on the same network. First, obtain the server’s IP address:

$ ip addr show | grep inet.*brd
    inet 192.168.242.128/24 brd 192.168.242.255 scope global dynamic noprefixroute ens33

Start the server: $ iperf -s On the client, connect to the server’s IP: $ iperf -c 192.168.242.128 The test runs for a few seconds and reports the achieved bandwidth.

These three tools—fast, speedtest, and iPerf—cover quick one‑off checks, detailed server‑based measurements, and advanced bandwidth testing, allowing you to monitor and script network performance on Linux and other platforms.