ubuntu file permissions under / [closed]

view story

http://stackoverflow.com – I want to make my ubuntu 12.04 home server a little more secure. Actually I would like to have paranoid security. For starters I would like to change the default permissions under the / folder. These permissions are by default set to 755 for most folders (rwxr-xr-x). I would like to change them to 751. Do you think this might cause a problem? If so why would it? Does the OS need read permissions for others? I can understand that a user (like www-data) should be able to cd in a directory but why does he need to be able to read its contents if it is provided with the full path? I searched for a (HowTos)