GitHub - arjunshajitech/netbad: Break your network on purpose

Break your network on purpose, to test how your software copes.

A friendly wrapper around Linux tc + netem. Linux only.

Why this exists

sudo tc qdisc add dev eth0 root netem loss 10% delay 100ms

I keep googling the same tc commands. I keep copy-pasting things I didn't want to understand again. I keep thinking: "there has to be a better way to say this."

So I wrote netbad.

This is the tool that worked for me. It may or may not work for you. That's fine.

Install

git clone https://github.com/arjunshajitech/netbad.git
cd netbad
sudo install -m 755 netbad /usr/local/bin/netbad

Check it worked:

Uninstall: sudo rm /usr/local/bin/netbad

Use

netbad drop 10%          # lose 10% of packets
netbad delay 100ms       # add 100ms of delay
netbad shuffle 10%       # deliver 10% out of order
netbad duplicate 5%      # send 5% of packets twice
netbad corrupt 1%        # flip a bit in 1% of packets
netbad limit 1mbit       # cap the bandwidth

netbad status            # what's happening now
netbad list              # all interfaces and their state
netbad clear             # put it back to normal

No sudo needed — netbad asks for it when it needs it.

Extras

Add these to any command:

netbad drop 10% on eth0     # pick an interface (default: your internet one)
netbad drop 10% for 30s     # undo it automatically after 30s
netbad delay 100ms --only   # replace what's applied instead of adding to it
netbad drop 10% --dry-run   # show the tc command, change nothing

Impairments stack — netbad drop 10% then netbad delay 100ms gives you both.

Good to know

Only outgoing traffic is affected. That's how netem works.
It hits all traffic on the interface, not one app or port.
Careful over SSH — use for 30s so it heals itself.
Nothing survives a reboot. netbad clear all fixes anything you forgot.