ch.3

sudo

limited su -takes as its argument a command line to be executed as root, and then consults the file /etc/sudoers, which lists the people who are authorized to use sudo and the commands they are allowed to run on each host -keeps a log of command lines that were executed

what is root

it is the superuser account of UNIX. root is the user name or account that by default has access to all commands and files on a Linux or other Unix-like operating system.

su

substitute user identity. -doesnt record commands executed as root but does create a log entry that states who became root and when -executes commands with the privileges of another user account.

What is a virtual machine

(VM): software implementation of a machine that executes programs like a physical machine. It shares physical HW resources with the other users but isolates the OS/application to avoid changing the end-user experience

cons of sudo

-Breach in security of a personal account = root account -Logging can be subverted •Sudo csh •Sudo su -Select the commands for sudowith care •No shell scripts •No utility which provides shell escapes •No " all commands except .

pros of sudo

-Command logging -accountabilities -Operators can do chores without unlimited root privileges -Hide the real root password -Revoke the privilege without change root password -A canonical list of all users with root privileges is maintained -Less chance of root shell left unattended -A single file can be used to control access for an entire netw

Why use virtualization

-Running multiple OSs simultaneously -Easier software installation -Disaster recovery (snapshots or states) -Infrastructure consolidation

what is a guest OS?

This is the OS that is running inside the virtual machine

Advantages of sudo vs root login

root login allows you to access any file, run any program, execute any system call, and modify any setting sudo lets you execute one command with superuser privileges as long as your user id is in the sudoers file, giving you the necessary authorization

how does the system recognize a root user

the uid is 0

what is a host OS?

this is the OS of the physical computer on which VMware is installed

How to become root

we cannot login directly as root user -su -sudo

why is it a bad idea to login as root

we cannot login directly as root user, because we cannot see the changes that were made previously, unauthorized access is possible, and no record of who was doing the work