Iperf Network Performance

Install iperf3

sudo apt install iperf3

Basic usage

Server mode

iperf3 -s
iperf3 -s -p 5201  # Custom port

Client mode

iperf3 -c server-ip
iperf3 -c 192.168.1.100

Test duration

# 30 second test
iperf3 -c server -t 30

# 100 MB transfer
iperf3 -c server -n 100M

TCP testing

# Default is TCP
iperf3 -c server

# Reverse direction (server sends)
iperf3 -c server -R

# Bidirectional
iperf3 -c server --bidir

UDP testing

# UDP mode
iperf3 -c server -u

# Set bandwidth
iperf3 -c server -u -b 100M

# Packet loss and jitter
iperf3 -c server -u -b 10M

Parallel streams

iperf3 -c server -P 4  # 4 parallel connections

Output formats

# JSON output
iperf3 -c server -J

# Human readable (default)
iperf3 -c server

# Interval reports
iperf3 -c server -i 1  # Every second

IPv6

# Server
iperf3 -s -6

# Client
iperf3 -c server-ipv6 -6

Common scenarios

Test bandwidth

# Server
iperf3 -s

# Client
iperf3 -c server -t 10

Test latency (UDP)

iperf3 -c server -u -b 1M -t 30

Multiple streams

iperf3 -c server -P 10 -t 30

Reverse test

iperf3 -c server -R -t 10

Save results

# JSON to file
iperf3 -c server -J > results.json

# Log file
iperf3 -c server --logfile test.log

Port options

# Custom port
iperf3 -s -p 9999
iperf3 -c server -p 9999

# Bind to specific interface
iperf3 -s -B 192.168.1.100

Throughput testing script

#!/bin/bash
SERVER=$1

if [ -z "$SERVER" ]; then
    echo "Usage: $0 <server-ip>"
    exit 1
fi

echo "Testing TCP throughput..."
iperf3 -c $SERVER -t 10

echo -e "\nTesting UDP throughput (100 Mbps)..."
iperf3 -c $SERVER -u -b 100M -t 10

echo -e "\nTesting with 4 parallel streams..."
iperf3 -c $SERVER -P 4 -t 10

Firewall

# Allow iperf port
sudo ufw allow 5201/tcp
sudo ufw allow 5201/udp

Troubleshooting

# Check if server is running
netstat -tuln | grep 5201
ss -tuln | grep 5201

# Test connectivity
telnet server 5201
nc -zv server 5201