I didn't know at all how kernel modules worked. This is me learning
how. This is all tested using the 3.5.0-18 kernel.
hello.c: a simple "hello world" module
hello-packet.c: logs every time your computer receives a packet.
This one could easily be modified to drop packets 50% of the time.
rootkit.c: A simple rootkit.
blog post explaining it more
I'm running Linux 3.5.0-18. (run uname -r) to find out what you're
using. This almost certainly won't work with a 2.x kernel, and I
don't know enough. It is unlikely to do any lasting damage to your
computer, but I can't guarantee anything.
I have my kernel sources set up in /lib/modules/3.5.0-18-generic. I
think I only needed to run
sudo apt-get install linux-headers-3.5.0-18-generic
but I don't remember for sure. If you try this out, I'd love to hear.
To compile them, just run
make
sudo insmod hello.ko
dmesg | tail
should display the "hello world" message