bfforever / kernel-module-fun

Some fun things you can do with kernel modules (all "bad ideas")

Kernel module fun

Motivation

I didn't know at all how kernel modules worked. This is me learning how. This is all tested using the 4.19.0-9 kernel.

Contents

hello.c: a simple "hello world" module

who-connect-me.c: a custom netfilter hook to log remote address from TCP SYN packet

Wireshark filter condition

tcp.port eq 8888

Compiling them

I'm running Linux 4.19.0-9 / 5.4.0-150. (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.

sudo apt-get install linux-headers-$(uname -r)

but I don't remember for sure. If you try this out, I'd love to hear.

To compile them, just run

make

Inserting into your kernel (at your own risk!)

sudo insmod hello.ko
dmesg | tail

should display the "hello world" message