$ cd $HOME/devel/hello-netlink/kernel
$ make all

$ cd $HOME/devel/hello-netlink/user
$ gcc -o nl_user nl_user.c $(pkg-config --cflags --libs libnl-3.0)

$ cd $HOME/devel/hello-netlink/kernel
$ sudo insmod nl_kernel.ko

$ lsmod | grep -i "nl_kernel"
nl_kernel              16384  0
$

$ cd $HOME/devel/hello-netlink/user
$ ./nl_user -m "Hello from Ilies"
User send the following message to the kernel:
Hello from Ilies
User receive a message from kernel: Hello from kernel
$

$ $ tail -f /var/log/kern.log

Sep 20 22:44:48 dev-machine kernel: [13466.108923] Entering: init_module
Sep 20 22:45:42 dev-machine kernel: [13520.057427] Entering: nl_recv_msg_cb
Sep 20 22:45:42 dev-machine kernel: [13520.057430] Kernel receive a message from user:Hello from Ilies

$ sudo rmmod nl_kernel