Why won't chmod +s allow me to do stuff in root's stead?

Question

I have a very specific command I'd like anyone to be able to run. For the sake of example, let's pretend the command is ip addr flush dev foo0.

I found this and this. Unless I'm misunderstanding something, I think it's exactly what I need.

echo "ip addr flush dev vboxnet0" > script.sh
chmod +x script.sh

chmod +s script.sh
sudo chown root script.sh
sudo chgrp root script.sh

But then,

./script.sh
Failed to send flush request: Operation not permitted

Why?

Answer 1

I came across this situation some weeks back and found this in the course of my research. Perhaps it will help you as well.

https://superuser.com/a/636800