GitHub - daxtens/gso: Explore the inner workings of Generic Segmentation Offload in Linux with me!

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Explore the inner workings of Generic Segmentation Offload in Linux with me!

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Name		Name	Last commit message	Last commit date
Latest commit History 2 Commits
LICENSE		LICENSE
README		README
probe-segmentation.py		probe-segmentation.py
ufo.c		ufo.c

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GSO - Generic Segmentation Offload - is magic sauce that makes Linux
networking go faster.

Usually it works automatically at the kernel level, without user
intervention.

However, for testing, it can be helpful to be able to construct your
own GSO packets. The AF_PACKET socket type allows you to insert GSO
packets from userspace using infrastructure from virtio_net. However,
I was unable to find any example code on the internet that showed how
to use this. So after reading a lot of kernel source, this is my
attempt to provide a complete, working example of getting GSO packets
into the kernel and out to the network.

This repository contains:

 - ufo.c: code to insert a UDP GSO (UFO) packet.

          Edit the constants at the top of the file to provide your
	  own interface and destination MAC/IP, then set a listener
	  on the destination on UDP port 23452.

          Requires CAP_NET_ADMIN, so run as root.

 - probe_segmentation.py: example python+eBPF C code to show the 
                          process of segmentation using eBPF kprobes.
                          Needs https://github.com/iovisor/bcc

TODO
----
 * include more eBPF examples
 * (eventually, maybe) TSO sample code