We all think that chmod is there just to help us and it can never do any harm to the system. But hey wait for a sec... too much of a permission can be dangerous too. I came to know about this today when one of my team member has just ran the below command on one of our Linux servers.
chmod -R 777 *
As soon as this command is executed Linux system has suspected something wrong has happened and it stopped serving any service. I was not even able to do ssh to the box. I had to change the permissions (reduce the permissions) on the files to make the system ssh working.