Seong-lae Chomode of access - read, write, execute
FCB - Storage structure consisting of information about a file.
- three classes of users - each has different mode access
- owner access - read, write, execute - 7
- groups(unique name) access - read, write - 6
- public access - execute - 1
so if you want to 보안 OS, architecture is most important 암호화는 보안의 일부 system information 보안 important