Fancy 25 gigabit symmetric fiber getting you down? Impossibly low latency and packet loss providing an unacceptable advantage to your professional Starcraft career? Envious of Wilson next door's literal wet string DSL connection?

Try our eBPF Network Vershitifier! With one simple* CLI tool, you can easily target any binary on your Linux system for unexpected packet loss. We support all percentages between 0% and 100%.

This repo contains a simple ebpf-go application that randomly drops packets for targeted processes using the eBPF TC filters. The TC action TC_ACT_STOLEN is used to pretend to the caller that the packet was processed successfully, which makes the packet loss induced look the same as if it's dropped somewhere on the wire.

eBPF probes attached to sys_execve are used to discover instances of our targeted application as they are launched. Next, a probe is attached to BPF_CGROUP_INET_SOCK_CREATE to discover sockets created by the given processes, and mark them for packet loss by setting a socket cookie on the socket.

You specify both which process to drop packets for, and what percentage of traffic to drop:

> sudo ./vershitifier -command ping -interface enp67s0 -drop 50 
2024/06/20 17:09:57 Attaching to interface enp67s0
2024/06/20 17:09:57 Started up. Dropping 50% of traffic for ping 

You can also run a simple demo in a docker container:

./docker-run.sh

If you want to hack on this and you happen to be using Arch Linux, you'll need the following bits:

pacman -S base-devel
pacman -S go
pacman -S llvm
pacman -S clang
pacman -S linux-headers

# Fix systemd madness
ln -sf ../run/systemd/resolve/stub-resolv.conf /etc/resolv.conf