Example adapted to newer Linux kernel versions.
Compile kernel module and user space program.
make
Load kernel module:
insmod ./netlink_test.ko
Also check kernel log dmesg for module debug output.
./nl_recv "Hello you!"
Listen for message...
Received from kernel: Hello you!
Listen for message...
Execute ./nl_recv in another console as well and see how the message is send to the kernel and back to all running nl_recv instances. Note: Only root or the kernel can send a message to a multicast group!
Unload kernel module:
rmmod netlink_test.ko