I am sort of new to linux but have noticed something disturbing about it.

In a few of the manuals I have read they cover the "what if root password is lost" question. THe answer some give is to just simply re-install linux. But one said to try typing "linux single" at the lilo/grub prompt.

I tried this and was able to type passwd root and change the root password.

Is there a way to disable this? If not what happens if someone get in front of a major linux driven network computer and decides as a joke they will just change the root password?