netimpair

An easy-to-use network impairment script for Linux written in Python

netimpair.py is a CLI tool that simulates bad network conditions on Linux machines. It essentially is a wrapper script around the Linux netem module and the tc command. Using tc and netem is sometimes difficult, unintuitive or tedious at best, especially if you only want to impair a specific subset of network traffic. netimpair.py automates all of this and provides a simpler CLI interface for basic network impairment needs.

NOTE: Fedora users may need to install kernel-modules-extra if they're getting RTNETLINK: No file or directory found errors)

netimpair.py can do the following things:

Simulate packet loss, duplication, jitter, reordering, and rate limiting
Selective impairment based on ip/port
Inbound or outbound impairment
Automatically cleans up any impairment on exit or Ctrl-C

netimpair.py is a Python 3 script. For systems that only support Python 2 in its default repositories (i.e. CentOS 6), you can use netimpair2.py

####Jitter

# Add 200ms jitter
sudo ./netimpair.py -n eth0 netem --jitter 200

####Delay

# Add 200ms delay
sudo ./netimpair.py -n eth0 netem --delay 200

####Loss

# Add 5% loss
sudo ./netimpair.py -n eth0 netem --loss_ratio 5

####Rate Control

# Limit rate to 1mbit
sudo ./netimpair.py -n eth0 rate --limit 1000

####Impair inbound traffic

# Append --inbound flag before the impairment keyword to apply inbound impairment
# For example, this applies 5% loss on inbound eth0
sudo ./netimpair.py -n eth0 --inbound netem --loss_ratio 5

####Selectively impair certain traffic

# Add 5% loss on packets with source IP of 10.194.247.50 and destination port 9001
# NOTE: Specifying include flag overrides the default include, which impairs everything
sudo ./netimpair.py -n eth0 --include src=10.194.247.50,dport=9001 netem --loss_ratio 5
# Exclude packets with destination IP 10.194.247.50 and source port 10000
sudo ./netimpair.py -n eth0 --exclude dst=10.194.247.50,sport=10000 netem --loss_ratio 5
# Exclude SSH 
sudo ./netimpair.py -n eth0 --exclude dport=22 netem --loss_ratio 5
# Exclude a certain source IP on all ports
sudo ./netimpair.py -n eth0 --exclude src=10.194.247.50 netem --loss_ratio 5

####Additional parameters can be found with the help option

# Basic help
./netimpair.py -h
# Help for the netem subcommand
./netimpair.py netem -h
# Help for the rate subcommand
./netimpair.py rate -h

prodigeni/netimpair

netimpair