1. Chapter 3 3.1 Introduction 3.2 The UNIX Model of Ownership
3.3 The Superuser
3.4 Choosing a Root Password
3.5 Becoming Root
3.5 Other Important Users

2. 3.1 Introduction
DEMIGOD
In UNIX the superuser is the only user to have power to perform all priviledged tasks.

3. 3.2 The UNIX Model of Ownership
Ownership of Files
owner
group owner and GIDs, named in /etc/group
UIDs in /etc/passwd
Ownership of Processes
ea process has four numbers associated with it
one real UID, one effective UID, one real GID and one effective GID

4. 3.3 The Superuser UID of zero a.k.a. root
may perform any valid op on a file or process
may execute some system calls
may change ownership credentials at will
login program

5. 3.4 Choosing a Root Password
should not be easily guessed or discovered
random sequence of letters, punctuation, & digits
case sensitive
only first eight characters are significant
change password too

6. 3.5 Becoming Root may login as root “su” to root
“su username” as root to get to an account
must be in “wheel” group
sudo: A limited su
/etc/sudoers lists people authorized
who and what are logged
timeout protected

7. 3.6 Other Important Users root is only user with special status
some nonhuman logins for special purposes
daemon: Owner of Unprivileged Software
bin: Owner of System Commands
sys: Owner of the Kernel & Memory Images
nobody: Owner of Nothing