sudo = POWER!! (managing users in Linux) // Linux for Hackers // EP4

Summary

This video script is a fun and educational journey into Linux user management, presented through a 'hacking' lens with a Marvel Avengers theme. It covers creating and deleting users, changing user details, and understanding permissions with sudo. The tutorial uses a free Linux lab provided by Hack The Box Academy, allowing viewers to follow along and learn essential Linux skills while engaging with the entertaining narrative of assembling the Avengers to stop Thanos.

Takeaways

• 😀 The video is an educational tutorial on managing users in Linux, covering creation, deletion, and modification of user accounts.
• 🛠️ The script introduces commands like 'adduser' and 'useradd' for creating users, with 'adduser' being more interactive and 'useradd' being quicker but less detailed.
• 🔒 It explains the importance of the 'sudo' command, which provides superuser permissions for executing commands that require higher privileges.
• 🤖 The video uses a humorous analogy of assembling the Avengers to fight Thanos, relating to the process of adding users and granting them powers in a Linux system.
• 📝 The script covers the significance of the '/etc/passwd' and '/etc/shadow' files, which store user account information and hashed passwords, respectively.
• 👤 It discusses the concept of User IDs (UID) and Group IDs (GID), which are assigned to users and groups upon creation.
• 🏠 The tutorial mentions the creation of home directories for users and how some commands, like 'useradd', do not create them by default.
• 🔄 The script explains how to modify user accounts using the 'usermod' command, allowing changes to properties like shell preference and username.
• 👥 The importance of groups in Linux is highlighted, showing how users can be part of multiple groups and how to manage group memberships.
• 💪 The 'sudoers' file is introduced as the key configuration file that defines who can use 'sudo' and what commands they are allowed to execute.
• 🗑️ The process of deleting users and groups is covered, demonstrating how to remove accounts and groups using 'userdel' and 'groupdel' commands.

Q & A

What is the main topic of the video script?

The main topic of the video script is managing users in Linux, including creating, deleting, and modifying user accounts, as well as understanding permissions and the sudo command.

What is the significance of the 'add user' and 'user add' commands in Linux?

The 'add user' command is used to create a new user account in Linux and it performs additional setup tasks such as creating a home directory and setting a default shell. The 'user add' command also creates a new user but does not perform these additional tasks, hence it's considered 'lazy'.

What does the 'sudo' command represent in Linux?

The 'sudo' command stands for 'super user do' and allows a permitted user to execute a command as the superuser or another user, effectively granting temporary root privileges for that command.

How can you check the list of users on a Linux system?

You can check the list of users on a Linux system by using the 'cat /etc/passwd' command, which displays the contents of the passwd file containing user account information.

What file stores the hashed passwords in Linux?

The hashed passwords in Linux are stored in the '/etc/shadow' file.

What is the purpose of the 'usermod' command in Linux?

The 'usermod' command is used to modify the details of an existing user account, such as changing the user's shell, home directory, or group memberships.

What does the 'su' command do, and how is it different from 'sudo'?

The 'su' command is used to switch to another user account, optionally becoming that user by providing their password. It is different from 'sudo', which allows a user to run a single command with the privileges of another user, typically the superuser.

What is the 'sudoers' file, and why is it important?

The 'sudoers' file defines policies for sudo command usage, specifying which users and groups can execute what commands and as what users. It is important because it controls who has the ability to perform administrative tasks on the system.

How can you delete a user in Linux?

You can delete a user in Linux using the 'sudo userdel' command followed by the username of the account you wish to remove.

What is the principle of least privilege mentioned in the script, and why is it important?

The principle of least privilege is a security concept where users are given the minimum levels of access necessary to perform their tasks. It is important because it reduces the risk of damage to the system in case of user account compromise.

How does the script relate the management of users in Linux to the Marvel's Avengers and the Infinity Gauntlet?

The script uses the theme of Marvel's Avengers and the Infinity Gauntlet as a metaphor to explain user management in Linux. It compares the sudo command to wearing the Infinity Gauntlet, granting superpowers, and the process of adding and deleting users to assembling and disassembling the Avengers team.

Outlines

00:00

🧙‍♂️ Introduction to Linux User Management

The script starts with an introduction to the importance of user management in Linux, targeting hackers and enthusiasts. It humorously references the Avengers assembling to stop Thanos, a metaphor for tackling Linux challenges. The video promises a comprehensive guide on creating, modifying, and deleting user accounts and groups, as well as managing permissions through sudo. The sponsor, Hack The Box Academy, is introduced as a platform for learning and practicing Linux skills with a free lab environment. The video encourages viewers to engage with the content and subscribe for more.

05:00

🔑 Creating and Verifying User Accounts

This paragraph delves into the process of creating user accounts in Linux, using the 'add user' command, and the importance of the root user's permissions. It explains how to check the list of users with the 'cat /etc/passwd' command and the significance of the 'x' marker indicating password storage in the 'shadow' file. The script also clarifies the difference between 'add user' and 'user add' commands, highlighting the latter's lack of interactive setup for additional user details.

10:01

🛠️ Modifying User Accounts and Understanding File Structure

The script continues with how to modify existing user accounts using the 'usermod' command, including changing the default shell and updating usernames. It provides insights into the structure of the '/etc/passwd' and '/etc/shadow' files, explaining the meaning of user IDs, group IDs, and home directories. The paragraph also contrasts the 'add user' and 'user add' commands, noting the latter's omission of default settings like home directories and shell types.

15:03

🤖 Granting Superuser Permissions with sudo

This section introduces the concept of superuser permissions in Linux, symbolized by the 'sudo' command, likened to wearing the Infinity Gauntlet. It explains how 'sudo' allows temporary root user capabilities to perform administrative tasks. The script also covers the 'su' command for switching user accounts and the importance of the 'sudoers' file in defining who can use 'sudo'. It humorously adds the character Thanos to the 'sudoers' file, granting him all powers.

20:04

👥 Group Management and sudoers Configuration

The script discusses the creation of user groups and the assignment of sudo privileges to these groups. It details the steps to add a group to the 'sudoers' file, allowing members to execute any command without a password. The paragraph also demonstrates how to add and remove users from groups, emphasizing the power dynamics between characters like Iron Man and Thanos in the context of the Infinity Gauntlet.

25:06

💥 Dealing with User and Group Deletions

The final paragraph covers the deletion of users and groups in Linux using 'sudo userdel' and 'groupdel' commands. It uses the narrative of Iron Man using the Infinity Gauntlet to restore deleted users, symbolizing the recovery of system resources. The script concludes with the principle of least privilege, emphasizing the importance of restricting powerful commands like 'sudo' to prevent misuse.

Keywords

💡Linux

Linux is an open-source operating system that is widely used for servers, mainframes, and supercomputers. In the video, Linux is the platform where user management is being taught, and it's integral to the video's theme of learning system administration and potentially ethical hacking.

💡User Management

User management in the context of the video refers to the process of creating, modifying, and deleting user accounts on a Linux system. It's a fundamental concept for controlling access and permissions, which is essential for system security and administration.

💡Sudo

Sudo, short for 'superuser do', is a command in Linux that allows a permitted user to execute a command as the superuser or another user, as specified by the security policy. In the video, sudo is likened to wearing the 'infinity gauntlet', symbolizing its power to grant temporary elevated privileges.

💡Sudoers

The sudoers file in Linux is a configuration file that specifies which users and groups can use the 'sudo' command to gain superuser privileges. In the video, editing the sudoers file is a critical step in granting or restricting access to the 'infinity gauntlet' of system administration.

💡User ID (UID)

A User ID, or UID, is a unique identifier for a user account on a Linux system. In the script, UIDs are mentioned as numerical identifiers that distinguish different users, with the 'add user' command automatically assigning a UID to new users.

💡Group ID (GID)

Group ID, or GID, is a unique identifier for a group in a Linux system. Each user has a primary group with the same GID as the user's UID. In the video, GIDs are used to manage permissions and access control at a group level.

💡Home Directory

A home directory is the personal space on a Unix-like operating system where a user's files are stored. In the video, creating a home directory for new users is part of the user creation process, providing them with a personal space to store their files.

💡Shell

In the context of Linux, a shell is a user interface for access to an operating system's services. It is either a command-line interface (CLI) or a graphical user interface (GUI). The default shell for new users in the video is 'bash', which is a common choice for command-line interaction.

💡Password Hashing

Password hashing is a security measure where passwords are transformed into a hash value for storage in a system. In the video, it is mentioned that the 'shadow' file stores hashed versions of passwords, ensuring that actual passwords are not exposed.

💡Avengers

The Avengers are a group of superheroes from the Marvel Comics universe. In the video, they are used as a metaphor for assembling a team of users to manage a Linux system and fight against the 'Thanos' threat, which adds a fun narrative to the educational content.

💡Hack The Box Academy

Hack The Box Academy is an online platform mentioned in the video for learning ethical hacking and cybersecurity. It is used as a sponsor and provides a free lab for practicing Linux user management, which is a key part of the video's educational content.

Highlights

Essential Linux user management skills for anyone interested in Linux or hacking.

Introduction to the concept of user accounts and permissions in Linux.

Explanation of creating, modifying, and deleting user accounts with 'adduser' and 'useradd' commands.

Difference between 'adduser' and 'useradd' commands in terms of functionality.

The importance of the 'sudo' command for gaining superuser permissions.

How to view and understand the /etc/passwd file for user account information.

The role of the /etc/shadow file in storing hashed passwords.

Creating user groups and the relationship between users and their groups in Linux.

Using 'usermod' to change properties of an existing user account.

The concept of the 'sudoers' file and its control over who can use 'sudo'.

How to edit the 'sudoers' file safely to grant or restrict 'sudo' access.

Demonstration of adding a user to the 'sudo' group to grant superuser permissions.

Using 'su' to switch between user accounts and the need for correct passwords.

The ability to delete users and the impact on system accounts.

Introduction to the concept of least privilege and its importance in system security.

How to create and manage groups with 'groupadd' and 'gpasswd' commands.

The process of adding users to a group to grant collective permissions.

Final thoughts on the importance of user management in Linux for security and system administration.

Transcripts

managing users in linux this is

essential you got to know this if you

want to get into linux or become a

hacker or do anything

don't skip this so assemble the avengers

we gotta stop thanos

what

welcome to linux for hackers and

everyone because everyone

needs to learn linux this is episode 4

and you don't want to miss this when

we're talking about user management user

accounts and linux and we're pretty much

going to cover everything from creating

users deleting them changing them

creating groups deleting those putting

on the infinity gauntlet and giving

yourself super godlike permissions

which is also known as sudo or the

sudoer's file we'll cover all that

and yeah we're gonna assemble the

avengers and stop thanos we're going to

save the world and when i say we i mean

we because you're going to do this with

me you're getting a free

linux lab right here in this video check

the link in the description thanks to

our sponsor

hack the box academy it's seriously

amazing free to sign up

hack the box academy is basically a

trading ground for hackers

good hackers mind you so if you want to

follow along with me learn how to manage

users in linux and save the world

then click the link below get signed up

for free and you'll have a linux

lab right here in your browser and then

of course whatever else you want to

learn regarding hacking it's there so

check that out too also hack the box

academy now has a student subscription

and you get cpe credits for completing

tier 1 modules or above

kind of killer check it out link below

to learn more have you hacked the

youtube algorithm today let's make sure

you do hit that like button subscribe

comment

notification bell let's hack youtube

today ethically of course

anyways no time to waste get your

stinking coffee let's do this

right now okay here we go we're going to

learn nearly everything you need to know

about managing users and linux

and we're gonna have a bit of fun with

it too so get your copy and let's go

now first we gotta launch our lab our

free linux lab from hack the box academy

so go ahead and navigate out there

hack the blogs account of me they are

our sponsor and they're amazing it's

completely free if you haven't already

signed up we'll get signed up i've got a

video walking you through that right

here

so log in to hack the box academy go and

click on the linux fundamentals course

to get started go ahead and open up the

user management module right here and

then to launch our free amazing phone

box our lab

scroll about halfway down and click on

start instance and it's going to start

quick coffee break just a little sip and

it is ready go ahead and click on

interact to uh

interact with it and i've said it before

this is amazing it's your free linux lab

in your browser that you can mess with

and break things and

let's do this okay let's talk about

users every computer system has a user

including linux and you know what you're

a user

to be able to log into the server this

linux box and do anything you have to be

a user on the system which user are you

let's see in a previous video we showed

this already so let's go ahead and

launch our terminal

our green or yellow box up at the top

here this is launching our shell

if you don't know what that is we'll go

back to the last video and watch that

one we talk all about it to quickly see

who you are you simply type in who

am i and there you are your user account

and you as user 86527 can log into this

linux machine

and do stuff you can launch programs

play games hack

create things delete things if you have

the right permissions we'll cover that

here in a moment

you you can do a lot of stuff as a user

of the system but not all users are the

same now hey

i've got some bad news we're under

attack our system our linux

box here we're being attacked by

thanos that's his name right the bad guy

from avengers yes thanos he's attacking

us

bad guy thanos is gonna snap his fingers

and destroy all our user accounts and we

won't be able to have fun on linux

anymore

we have to stop him but how do we do

that avengers assemble we need the

avengers right let's call them do they

have like a bat signal i don't know how

you call them

they just know they need help right or

that we need help but they're not in our

system right now we have to create these

user accounts to come and stop thanos

before he

snaps anyways let's start by adding the

avengers to our system

let's start with thor he's my favorite

so the command will be

add user thor and honestly it's that

simple that's all we need

the command add user will obviously add

a user but it's not the only one that

does this by the way just so you know

there's add user and then confusingly

there's another one called

user add which they do both add a user

but this command right here is a little

lazy

he doesn't do as much whereas this

command will do a lot i'll show you the

difference here real quick we'll bring

in our other avengers

anyways let's add thor real quick now

i'm going to hit enter but it's not

going to work

watch only root may add a user a group

to the system now what is a root

i mean root's another user on the system

if you watched our previous videos in

the series you would know all about root

not groot

root but we're going to temporarily

borrow some power from the root which

he's also known as the super user um so

what we're going to do here is hit the

up arrow to get our command back in

there add user thor we're going to go to

the beginning of our command

and type in sudo or it's also often

pronounced soo do but it's spelt sudo so

i want to say that

this is kind of like saying please in

linux please do this i'm getting super

powers to do this

again i'll explain more about that here

in a moment but anyways this is gonna

work

okay cool we got a fun prompt here let's

put a password in for thor i'm gonna say

hammer type it in again hammer full name

i think it's just thor

it'll ask you for all this random

information you don't have to put it all

in just enter enter enter

is it correct sure and thor's created he

is now a user on the system but how do

we know that where

is he well to find out what users are on

your system there's one simple place to

look

i'm going to clear my screen real quick

by typing in clear or i can just do

control

l whoo nice and clean there's a file in

the system that has a list of every user

on this

box or this system we're going to use

the command cat which we learned before

we're going to cat the forward slash

etsy forward slash pass

wd when we do that here's what happens

boom bunch of users on our system i bet

you're surprised like where all these

users come from i mean the first two we

recognize right i mean the last two

uh this one right here is us user blah

blah

and then thor the one we just created

there he is all these other entries are

indeed

user accounts on this system and they do

serve a purpose a lot of these you can't

log in

with like right here it says no login on

this account they do serve a purpose not

the topic for another video anyways now

real quick

what does all this right here mean it's

kind of gobbledygook right i mean the

first bit we understand what it is the

username

thor and user blah blah blah but what's

all the stuff after it well just after

the username we have

just an x sitting there all by himself

in fact you'll see this on pretty much

every user account appear

x max and what the x indicates is that

your password is stored in a separate

file called the

shadow file more specifically it's in a

place called etsy

shadow in linux we store our passwords

in the shadows where they're hidden you

can't see them but for real

if we go to it real quick we can

actually look at it let's do cat

etc etsy shadow oh permission deny we

need some

listen please sudo there we go and right

here next to the username thor we have

his password which that's actually not

his password

that's the hashed version topic for

another time anyways now just after x we

have two numbers

and they're the same we have one

thousand one and one thousand one what

are those

well those are his ids the first one is

his user id or a uid it's a number

which you can obviously see it's 1001.

the second one is his

group id we'll cover groups here in a

second but just know that when we create

a user in linux

we both create a user and a group for

that user so we have a username named

thor

we also have a group named thor and the

member of that group

is thor and then after that we got some

like random filler stuff like his name

and comments and stuff

and then after that we have his home

directory where he gives his hammer and

his

chest plate i don't know what thor has

his hair ties for thor his home

directory is in

the same place that a lot of people's

home directories are home

and then a directory called thor we'll

look at that here in a moment and then

just after that

we have his default shell when thor logs

into the system

what shell is he going to be given again

if you don't know what i'm talking about

go look at our previous video

but by default when we created his user

account with the add user command

it's going to be bash so that is what

all that gobbledygook means now let me

show you what the user add command does

our

alternative command which is kind of

weird so we have thor he's pretty

awesome but we need some extra help

i think we need iron man yeah yeah let's

get iron man in here so we'll do sudo

and instead of add user we're gonna

we're gonna do user

add and same as before we'll just type

in the user name iron man

and watch what happens here it is

different it's simple

that's it so remember add user like asks

hey put in his password

uh what's his first name last name

what's social security number

favorite flavor ice cream like all that

stuff this one just says

okay you're like uh what else

what do i do now that's what i meant by

saying that command is lazy because he

doesn't do anything but just say okay

yeah here's a user account i'm not gonna

do anything else like

set the password for you like you can do

that yourself um and i'll show you how

to do that here in a second but right

now

iron man is created but you can't really

do much with him so if we cat our

password file again to see what user

accounts we have in our system cat

slash etsy pass wd he's there iron man

is shown up

but there's a few things missing now for

example he has the x there saying that

his password's in the shadow file but is

it really because we didn't set a

password did we also notice here that

um his default shell is different it's

sh for

shell instead of bash so real quick i

want to take a look at the shadow file

to see if the stuff is there

that's interesting you can see that he

does have

an entry in the shadow file but it

doesn't seem to be a password

and i don't think it is but we can set

this password real quick command to set

a password for someone or change a

password for any username

is going to be password without the o-r

i'll show you so we'll we'll need super

powers sudo command is p-a-s-s-w-d

and then the user name so i'll type in

iron man and now we can set his password

jarvis there we go he's got a legit hash

there so we know it's working now one

thing the ad user command did not do for

iron man is it did not give him a home

he doesn't have a house right now he

doesn't have a home directory if i

navigate to the home directory well all

the

user directories live i go cd forward

slash home

and i type in ls i can see there are two

directories there for thor and then for

me

but iron man he doesn't have a home dude

and that's one downside of using the

user ad command

is again he's lazy he doesn't do this

kind of stuff if i jump into the thor

directory by doing cd

thor and then lsing his contents

yeah he's got a desktop he's got

templates if i do ls

dash al to reveal the hidden files he's

got a bunch of stuff going on in there

which we're not going to get into right

now i mean it is important but right now

we got to save the world

thor is here and he's coming clear our

screen now if we cap the password file

again

etsy pass wd i'm super annoyed that iron

man's

default shell is not the same as

everyone else's it's just sh

let's make sure it is bash we can modify

user account new command time are you

ready the command is

user mod which stands for user

modification and as you might expect it

will modify a user account now there are

a ton of things we can change if you do

dash h for help to see like what can i

do with this it'll tell you

a lot of stuff and i'm not going to

cover everything right now that take

forever and

thanos is here so i'll do sudo because

we will need special permissions

user mod and let's say i want to change

that shell for iron man

i'll do iron man say that's who i want

to change it for

dash dash shell and i'll say ben

bash done and if we cap the user or the

cat the password file once more welcome

iron man you now are using bash just

like everyone else

and we can change other things too like

maybe his name like sometimes iron man

isn't iron man sometimes he's tony stark

so if we do sudo user mod once more

we'll use the switch

dash l and then we'll put in the new

information

tony stark that's his new username and

then the old one

iron man done so if i cat the password

file once more

huh he's tony stark now but we don't

need tony stark right now we need iron

man let's change it back

okay better okay here we go now again

thanos is here and we need more than

just two avengers

avengers assemble let's create more

right now real quick

fast and that is where the user add

command comes in handy because you can

add things really quickly enough to go

through a menu every single time so

we'll just do it real quick

and we also have switches to help us

with that if i do user add dash h

we can do a lot of the stuff that the

add user command does just in one line

so i'll do user add let's bring in

hulk and i'll do a dash m which dash m

will actually create a home directory

form so whereas iron man didn't get one

by default i almost forgot we need

superhero permissions there we go let's

get spider-man in here

loki why not oh we can't forget captain

america

and i suppose we'll need doctor strange

i don't like that movie that much

didn't like it at all wasn't a fan but

he kind of played a key role so we'll

put him in here

so now we have some avengers if i do uh

cat

etsy password file boom

we got them they're here if you've seen

the movies you know it doesn't go

great at first thanos does get the power

he gets the

the gauntlet or what is it called ah

okay the infinity gauntlet almost forgot

actually i did forget i had to look it

up thanos has the power and he does

flick his fingers or snaps fingers and

do some bad stuff

now i'm gonna add the user account

thanos

we're bringing him in he's there i'm

going to set his password real quick

password inevitable let's see if he's

here yep there's thanos

now here in linux the infinity gauntlet

that gives you super

awesome powers and has all the stones

and you can flick your fingers and

everyone disappears

in linux that's definitely the pseudo

command

or pseudo we haven't really dived into

that deeply just yet

but right now we are it's a command we

use all the time it stands for

super user do essentially every time we

use that command it's like we're

slipping on the infinity gauntlet

the super powerful glove and this is the

worst glove you'll ever see we slip that

glove on and for one moment

we have powers to do whatever we frickin

want so the sudo command or the sudo

command

were able to grab the powers of the

super user the root user

and use them for that command now the

super user in the system

which is the root user he's the boss he

can do whatever stinking wants on linux

he can change all the settings

he can delete all the settings he can

ruin everything delete half your stuff

rmrf man that's what thanos is gonna do

and if you can use the pseudo command to

impersonate him just for a moment

that's a pretty stinking powerful

command it's a command that you don't

want to just give to anyone you want to

restrict that access and by default it

is pretty restricted

now you can see that right now we've

been using sudo all day

we have the infinity gauntlet we can put

that sucker on and use it whenever we

want to

but not everyone can use it for example

iron man he can't use it we can actually

pretend to be iron man real quick

new command time you ready the command

is s u

s u allows us to impersonate another

user we're actually switching

users we're becoming this user so let's

become iron man

i've always wanted to be iron man let's

do this so again the command is su

we'll do a space a dash or a tick space

and then the username of who we want to

switch into

now real quick by default if you don't

put anything here just

su space dash it's going to switch you

to the root user

which we can do like watch and i don't

know the root password

um actually but we can do this we can

put our gauntlet on

put the affinity gauntlet on sudo su

space dash i just became the root user i

just became the infinity gauntlet which

is kind of weird

you never want to become the infinity

gauntlet never log in as root that's why

we have sudo so i'm going to hit ctrl

d or we can just type in exit or

log out either of any of those so i'll

just do ctrl d

to become myself again but anyways back

to becoming iron man so i'll do su

space dash iron man now doing this

without the gauntlet on i will have to

know iron man's password this goes for

any time you use the su command but if i

were to use sudo

and put my gauntlet back on i don't have

to put a password in but anyways

i'll become iron man put his password in

jarvis

i'm iron man now iron man is pretty

powerful but he cannot use a pseudo

command let's try it real quick

i'll do sudo and i'll try to add a user

user add

let's try to bring in pepper potts his

wife right yeah wife

that's gonna ask for a pseudo password

okay just type in jarvis

things are looking pretty good right no

we're in trouble

you're not in the sudoers file this

incident will be reported you're like

you're grounded iron man you can't do

this i do love that we're talking about

marvel and we have this spider-man line

that comes in

anyways that's an overused line anyway

um so real quick

what is this right here the sue doers

file which is a very very awkward phrase

basically this file the sudor's file

defines

who can use sudo who can wear the

gauntlet right now iron man

is not in that file so we can't put it

on so what do you say we go take a look

at that file i know you're itching to so

let's do it real quick now the scooters

file is a very important file that you

don't want to jack up

and you can jack it up you can ruin your

entire system by

messing up the scenarios file but there

are some checks in place to keep you

safe now normally in linux

to edit a file you might just use your

default text editor right the one you

love like we might use

nano or them but with a suitor's file

the best practice is to do but with the

scooter

but with these two doors file there's a

certain way we have to do it now we will

have to use sudo to do this so i'm going

to stop being iron man for a second i'm

going to

ctrl d to log out of iron man okay i'm

me again the command will be sudo

and then right after that it'll be vi

sudo this is the only best practice

recommended way to

edit the sudoers file so let's uh get in

there and take a look and it's not a

crazy big file either it's kind of

simple in a way so i'll hit enter

and we're in and then i'll scroll down

through this document to

about here right here is where we're

able to see who's got permission to do

what obviously root can use sudo and

i'll explain what all this means here in

a moment and then down here in this

section we have allowed members of a

group

pseudo access or pseudo to execute any

command and then just below that we have

something else we have a percent sign

and then

pseudo this actually is a group and if

you're a member of this group the sudo

group

well you can do all this and what this

actually means is you can enter

any command at all and you don't have to

enter

a password which is pretty dangerous

kind of risky but

it's okay so if you're in this file

you have the power and thanos does have

the power let's go ahead and add thanos

real quick

we'll pretend he's already in there so

just under root i'm going to add thanos

so we'll start with the username which

is

thanos the first option here is what

systems

can thanos have ultimate power on well

it's the infinity gauntlet

all systems and this would be if they're

like multi-system situations but

and then i'll do a space equals not plus

sign

equals all and that all stands for all

commands now if you want to just give

thanos options to do one thing like

maybe add a user we might do forward

slash

sbn forward slash user add giving him

access to that one command

we don't want to do that thanos has all

power

oh and that's all we need i'm going to

hit control

x to say i want out of here don't want

to save it hit y

hit enter to write it to that file and

thanos is there

he's got the gauntlet on he can do

whatever he wants let's see if he can

we're going to become thanos for a

second so i'll do sudo

su space dash space thanos

we're thanos right now so let's do sudo

user ad what's another bad guy he uses

oh yeah his daughter nebulous little

spring nebula in here the stanos have

access let's see

what's his password inevitable yep

it did it worked so let's cap the uh

password file yep there's nebula

so thanos has ultimate power he's got

the gauntlet on

and crap he's about to snap you ready

he's going to delete half the

population in our case half the avengers

we have here to delete a user

new new command time it's terrible but

new command time coffee break

okay i'm ready sudo user

del or user delete as you might expect

this command will

delete a user and we'll take out thor

thor is gone if we catch the password

file

thor he's gone pseudo user delete

spider-man gone bye doctor strange

gone and just like that with a snap of

his fingers we're down to

hulk loki and captain america oh and

iron man two there he is

and just when it seems hopeless just

when it seems all is lost the avengers

have a plan ant-man comes in somehow

quantum stuff anyways we need the

gauntlet we need pseudo access to be

able to

bring captain america back and all the

other people got got deleted so let's do

this right now so

we're gonna explore a new concept we're

going to create a group to do that

new command time here we go we'll do

sudo group

add and as you might expect group add

will simply add a new group i'll do a

space i'll name my group

infinite

gauntlet does spell that right i don't

care that's what it's going to be called

and the group is there but how do we

know where is that group at

well just like we have a password file

to look at our users in the system

we have a file to look at the groups and

it's much more self-explanatory it makes

more sense

i'm going to cat the etsy group

file and there it is infinity gauntlet

right there

as well as every other group that was

created for our users

i told you whenever a user account is

created also they have a group created

for themselves as well

now what i want to do is make sure that

the members of the infinity gauntlet

group

do have ultimate power because you mean

you should you have the infinity

gauntlet on

so we need to add the infinity gauntlet

group to our sudoers file

let's do that real quick so again we'll

do sudo vi sudo to edit that file the

only way to do it don't you ever do it a

different way

i'm just kidding but seriously um let's

edit that file we're gonna scroll down

to

where we were and then right here right

now we see that members of the sudo

group

can do whatever they want and actually

real quick let me show you the reason we

can do whatever we want

is because we're members of the sudo

group if i do

actually new command time if you just

type in group i'm sorry

groups groot

it'll tell you what groups you are a

member of the current user account

you're logged in as and here i'm a

member of my own group user 86527

and the pseudo group which gives me

gauntlet

access anyways let's make sure the

gauntlet does have the appropriate

permissions here so just under

the sudo group i'm going to add percent

infinity

gauntlet make sure you spell it right

i'll do a space and i'll pretty much

copy the one just above it i'll say all

which again is all systems

space equal sign space i'll say no

password which is nopa sswd like we see

here

i'll do a colon and say all essentially

it's saying you can do everything you

want

all commands and you don't need a

password you got all them stones

anyways so i'm going to hit control now

actually you know what real quick before

i do that

i'm going to mess it up like i mentioned

before if you mess up your suitors file

you can break the entire system

there is some checks in there that'll

keep you safe so i'll just go

and i hit control x to get out of there

yes to save hit enter it'll say whoa

whoa whoa

there is a syntax error right there not

supposed to do that what are you doing

what are you going to do now what do you

want to do are you sure you want to save

this if i hit enter it will give me some

options

and i love this it's like you might want

to go edit it again hit e

hit x to get out of there and don't save

it just forget what you're doing you

don't know what you're doing or says you

know what if you're pretty confident

just hit q and say you want to save it

danger um let's be smart let's hit e to

edit it

and remove that crap we put in there and

then we can hit ctrl

x y and enter no errors we're good

so the infinity gauntlet group does have

ultimate sudo

super user due powers and now what's

left is the avengers have to somehow

become part of that group

put on the glove and change history and

if you've seen the movie

spoiler alert um iron man he does this

so we need to somehow get iron man into

the infinity gauntlet group let's do

that right now now real quick let's

demonstrate that iron man can't do crap

right now so if i

become iron man and i try to bring back

spider-man i can't i don't have the

glove i can't do it man iron man is

helpless but let's add them to the group

so to add a user to a group

pretty simple we're going to use the

same command we used earlier to modify a

user the user mod command

so we'll do sudo and keeping in mind i'm

logged in as me now not ironman anymore

i'll do sudo

user mod and the switch is dash

g now dash g by itself will add this

user to a group

but it will add it to that group and

kind of eliminate all other groups

you may not want to do that so we often

want to change this to

dash lowercase a capital g the a stands

for append

so this command here we're appending the

groups that ironman

is part of so just after dash ag we'll

type in

the group which is infinity gauntlet

and then the user we want to add which

will be iron man

just like that iron man has the glove on

we can actually see if that's happening

by going to

or catting the group file

etsy group and here we can see the

infinity gauntlet group

the members over here on the right and

there's iron man right there now again

if you saw the movie you know that iron

man and

and thanos were kind of wrestling with

the gloves so thanos was in the group

too

they kept going back and forth let me

add thanos in there real quick

so yes right now iron man and thanos are

both part of this group they both have

super awesome

powerful pseudo access but eventually

iron man does wrestle the

glove off of thanos and puts it on

himself so new command time how do you

remove

a user from a group this command is

called g password

the commands sometimes are weird um so

we'll do sudo

g pass wd we're gonna do dash d for

delete specify the user we want to

remove which will be

thanos take that off take that take it

and then we'll specify the group

infinity gauntlet take that thanos look

at the group once more

no one's in there so anyways iron man he

has the gauntlet

he snaps his fingers and he creates the

users we lost

let me become iron man i am iron man

pseudo

user ad captain america pseudo

user ad spiderman done we'll bring back

doctor strange

and i forgot who else but anyways you

get the picture right iron man has the

gauntlet on he has the power he's part

of the group

and he can now bring back everyone and

shoot while he's at it let's defeat

thanos right

sudo user delete

thanos here we go

goodbye thanos and then finally iron man

realizes the infinity gauntlet it's too

powerful

for anyone to possess so he destroys it

i think that's what happens

that's what we're going to do right now

so using the principle of least

privilege

we're going to remove the the infinity

gauntlet group we're going to delete

that group by doing the

group delete command in fact iron man

will do it himself right now and he's

going to

delete his access to do it at the same

time which is kind of weird right

so sudo group delete uh new command time

i forgot to sit man

which obviously means we're gonna be

deleting a group and the usage is pretty

straightforward just after group delete

we'll enter the name of the group

infinity gauntlet now this does not

delete any

users in that group it just deletes the

group and gone are also iron man's

privileges to do anything special

anymore

for example if he got greedy and wanted

to create the group once more

sorry iron man you don't have it anymore

and i think you have other problems to

worry about

we did it i think like we saved the

world right i mean iron man's

not okay but we we learned how to manage

users and linux and in the process we

assembled the avengers and took away the

infinity gauntlet destroyed it and saved

the world

yeah but seriously we learned a lot

today we learned how to manage users in

linux

add them delete them groups permissions

all that

and that's essential to managing a linux

system to becoming a hacker to doing

anything with linux now and

pretty much every area of it involves

linux and also if you want a quick

review of what we covered in text form

uh mosey on over to hack the box academy

the page we were at the whole time

and look it over they've got the

commands we we talked about in text form

and they also have a delightful quiz at

the very bottom to test your knowledge

and see how you do

and if you get it right you earn cubes

back which with the junk or cubes

go watch episode one if you don't know

what they are also if you want to test

your skills even further

i've got a quiz in the description below

it's free click the link

and uh let's see what you got and again

huge shout out to our sponsor hack the

box academy

it's free to access right now to do what

we've been doing here if you want to go

further and learn how to hack wordpress

and

and do python stuff and just man just so

many things

check them out link below i'll catch you

guys next time

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