/proc

Hi, as one of security meausures, I learned that it is a good idea to do chmod 550 /proc/sys and chmod 550 /proc/net. First question I have, is this true? It seems right, because ordinary users cannot view network or system information, which is not a bad thing. Second question is, I implemented the above, but after a reboot permisions were back to standard ( I believe 555). How come? Thanks Max