isabella232 / rakelimit

A fair-share ratelimiter implemented in BPF

Rakelimit

A multi-dimensional fair-share rate limiter in BPF, designed for UDP. The algorithm is based on Hierarchical Heavy Hitters, and ensures that no party can exceed a certain rate of packets. For more information please take a look at our blog post.

Usage

To activate rakelimit create a new instance and provide a file descriptor and a rate limit that you think the service in question won't be able to handle anymore:

conn, err := net.ListenPacket("udp4", "127.0.0.1:0")
if err != nil {
    tb.Fatal("Can't listen:", err)
}
udpConn := conn.(*net.UDPConn)

// We don't want to allow anyone to use more than 128 packets per second
ppsPerSecond := 128
rake, err := New(udpConn, ppsPerSecond)
defer rake.Close()
// rate limiter stays active even after closing

That's all! The library now enforces rate limits on incoming packets, and it happens within the kernel.

Requirements

The library should be go-gettable, and has been tested on Linux 5.11.

You may have to increase optmem_max depending on your distribution:

sudo sysctl -w net.core.optmem_max=22528

You will need a clang-12 binary if you want to recompile the filter. Simply run go generate in the root of the project.

Limitations

• IPv6 doesn't support options
• requires tweaking of optmem
• not tested in production

Testing

go test .