The invisible file permission – chattr command
According to the chattr man page…chattr changes file attributes on a Linux second extended file system. So in addition to the usual chown/chmod etc. commands, the permissions you apply to a file or directory using chattr is not visible unless lsattr is command is used.
Applying chattr against certain files on the system can be very helpful such as locking down the /etc/shadow file or other configuration files.
To make file httpd.conf write protected so no one can modify it, type the command:
chattr +i /etc/httpd/conf/httpd.conf
The above command will not allow anyone including root to write to it, modify it and even delete it from the system. In order for root to write to it, it would have to use chattr again to remove the read-only flag.
To remove the read only and allow writes, type:
chattr -i /etc/httpd/conf/httpd.conf
Peace.