How to Accurately Measure Network Speed on Linux: Tools & Tips

Beginner: Built‑in Commands

Ping is the simplest way to verify basic network connectivity and latency. ping -c 10 www.baidu.com Key metrics displayed by ping are:

time : round‑trip time for each packet (lower is better).

packet loss : percentage of lost packets (0 % is ideal).

avg : average latency, indicating overall stability.

Ping measures only delay, not bandwidth, but it is sufficient for an initial health check.

Download Speed with curl/wget

Downloading a large file with curl or wget shows the real‑world transfer rate.

# curl
curl -o /dev/null https://nbg1-speed.hetzner.com/100MB.bin

# wget
wget -O /dev/null https://nbg1-speed.hetzner.com/100MB.bin

The terminal reports a speed such as 15.2 MB/s , which corresponds to roughly 120 Mbps (1 MB/s ≈ 8 Mbps). Testing multiple servers lets you compare regional performance.

Advanced: Professional Tools

speedtest-cli

Official command‑line client for Speedtest.net, providing standardized bandwidth measurements.

# Install via pip
pip install speedtest-cli

# Install via apt (Ubuntu/Debian)
sudo apt install speedtest-cli

Basic usage examples:

# One‑shot test
speedtest-cli

# Concise output
speedtest-cli --simple

# List servers and select one (replace SERVER_ID with the desired ID)
speedtest-cli --list | grep <em>keyword</em>   # find SERVER_ID
speedtest-cli --server SERVER_ID

iperf3

Precise bandwidth testing between two hosts, suitable for LAN performance analysis.

# Install on Ubuntu/Debian
sudo apt install iperf3
# Install on CentOS/RHEL
sudo yum install iperf3

Start a server on the remote host: iperf3 -s Run client tests from the local host (replace SERVER_IP with the remote address):

# Basic test
iperf3 -c SERVER_IP

# Test for 30 seconds
iperf3 -c SERVER_IP -t 30

# Reverse mode (measure upload speed)
iperf3 -c SERVER_IP -R

# Ten parallel streams
iperf3 -c SERVER_IP -P 10

iftop

Real‑time traffic monitor that shows which connections consume bandwidth.

# Ubuntu/Debian
sudo apt install iftop
# CentOS/RHEL
sudo yum install iftop

Run the tool: sudo iftop Useful interactive keys:

t – toggle display mode

n – show numeric ports

s – show source hosts

d – show destination hosts

nload

ASCII‑graph bandwidth monitor that visualizes upload and download rates.

# CentOS/RHEL
sudo yum install nload

Monitor all interfaces: nload Monitor a specific interface and set a 1‑second refresh interval:

nload eth0
nload -t 1000

Expert: Deep Network Analysis

nethogs

Shows bandwidth usage per process, helping you pinpoint which applications consume traffic.

# CentOS/RHEL
sudo yum install nethogs
sudo nethogs

bmon

Bandwidth monitor with graphical output and detailed statistics.

# CentOS/RHEL
sudo yum install bmon
bmon

vnstat

Daemon that records traffic statistics for later analysis, providing daily, monthly, and live views.

# Install and start
sudo yum install vnstat
sudo systemctl start vnstat

# Show today's traffic
vnstat -d

# Show this month's traffic
vnstat -m

# Show live speed
vnstat -l

Scenario‑Based Selection Guide

Quick connectivity check: Use ping – fastest and most direct.

External download speed: Use speedtest-cli or curl / wget – standardized or raw transfer rate.

Server‑to‑server bandwidth: Use iperf3 – precise, configurable, supports multiple modes.

Traffic anomaly investigation: Use nethogs – identifies the offending process.

Real‑time network status: Use iftop or nload – visual, comprehensive information.

Historical traffic analysis: Use vnstat – stores data for trend comparison.

Practical Tips

Permissions: Most monitoring tools require root; prepend sudo when invoking them.

Firewall considerations: When using iperf3, ensure TCP port 5201 is open, e.g. sudo firewall-cmd --add-port=5201/tcp --permanent.

Multiple runs: Network speed fluctuates; run tests several times and average the results.

Server selection: For external tests, choose a server geographically close to obtain more accurate measurements.

Combined workflow: Ping first for latency, then run speedtest-cli (or curl / wget) for bandwidth, and finally monitor with iftop or nload for real‑time behavior.