Chapter Introduction 3.2 The UNIX Model of Ownership

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Presentation transcript:

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

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

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

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

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

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

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

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