The goal of security is to maintain the integrity, availability and privacy of information entrusted to the system.
UNIX is a multi-user operating system and so it offers protection to one user's information from another. UNIX has a hierarchical file structure. This structure allows to implement the file security system.
UNIX provides three levels for protecting data -
1. Password Security
2. File Security
3. File Encryption
1. Password Security -
Passwords are one of the most important security features used today. The security is provided by assigning unguessable passwords and login names to indivisual users ensuring that anybody else cannot have access to the work.
2. File Security -
UNIX provides security at file and directory level. It classifies access control on files and directories according to three categories - User, Group and Others.
(A) User - The user is the owner of the file. There is always exactly one owner who has all the permissions. The owner of the file is the one who has created the file or to whom the ownership has been transferred.
(B) Group - The group has any number of members established by the system staff. A group is a programming team who share the same data for testing their programs. The members of a group have the same group-id but different user-id's.
(C) Other - The other members are anyone else who is neither the owners nor group members of a file. There are three forms of aaccess or permissions to any file - read, write and execute' which decide who can access a particular file, who can modify it and who can execute it.
3. File Encryption -
This utility encodes the file into an unreadable format, so that even if someone succeeds in opening it, the secrets are safe. For reading the file it needs to be decrypt.