12-05-2020

https://youtu.be/j7GrSo7XFdQ

User Administration

Root – Administrator – super user

- Root user has highest level of access

- Root user cannot be renamed

- Never share root password

- Don’t put password in chats or text messages

- Root user access to Company Data

Creat a user

[root@zmpt01 ~]# useradd terminator

The file /etc/passwd gets updated

terminator:x:1000:1000::/home/terminator:/bin/bash

User	Check for password	User id –UID	Group id – GID	User info text	User home	Shell type
Terminator	x	1000	1000		/home/terminator	/bin/bash

[root@zmpt01 ~]# id terminator

uid=1000(terminator) gid=1000(terminator) groups=1000(terminator)

UID – User Id	GID – user primary group	Group User is part of
uid=1000(terminator)	gid=1000(terminator)	groups=1000(terminator)

[root@zmpt01 ~]# id 1000

uid=1000(terminator) gid=1000(terminator) groups=1000(terminator)

Switching to regular user from root

[root@zmpt01 ~]# su terminator

[terminator@zmpt01 root]$ whoami

Terminator

Set the user password

[root@zmpt01 ~]# passwd terminator

Changing password for user terminator.

New password:

BAD PASSWORD: The password fails the dictionary check - it is based on a dictionary word

Retype new password:

passwd: all authentication tokens updated successfully.

Note: root user don’t have follow password restrictions, any password will be allowed

Set password as user terminatior

[terminator@zmpt01 ~]$ passwd

Changing password for user terminator.

Changing password for terminator.

(current) UNIX password:

New password:

BAD PASSWORD: The password is too similar to the old one

New password:

BAD PASSWORD: The password fails the dictionary check - it is based on a dictionary word

New password:

Retype new password:

passwd: all authentication tokens updated successfully.

Password file - Shadow file

[root@zmpt01 ~]# vi /etc/shadow

terminator:$6$pF2bCs4Z$Yifb7T/yi5uUkGm9lSpGRWxWPrXR.hwYEqbQkxOQ7npyTJpoTtjV

cWfxutdD0W4233i791Ud3Zt7Ec5t1/69C.:18601:0:99999:7:::

User	Password	Dec 31 1969	Grace Period	Expiration date from last update	Warning days
terminator	$6$pF2bCs4Z..	18601	0	60	7

Group file

[root@zmpt01 ~]# vi /etc/group

terminator:x:1000:

Group Name	Check for password	Group id - GID
Terminator	x	1000

Where is all the setting defined for users, groups and passwords?

[root@zmpt01 ~]# vi /etc/login.defs

PASS_MAX_DAYS 60

PASS_MIN_DAYS 0

PASS_MIN_LEN 5

PASS_WARN_AGE 7

UID_MIN 3000

UID_MAX 60000

GID_MIN 4000

GID_MAX 60000

[root@zmpt01 ~]# useradd xmen

[root@zmpt01 ~]# id xmen

uid=3000(xmen) gid=4000(xmen) groups=4000(xmen)

Assigning same password as a another user

[root@zmpt01 ~]# vi /etc/shadow

terminator:$6$87Fs/vJF$EHqhBznCvyU

5w4d3XsL6tfsaB7Q3WcDnf8xVB0.NwO

bSnBZo/Sw6KTG.qpBfvwvo.AkOajFd.PiKjuE1IAytQ.:18601:0:99999:7:::

xmen:$6$87Fs/vJF$EHqhBznCvyU

5w4d3XsL6tfsaB7Q3WcDnf8xVB0.NwO

bSnBZo/Sw6KTG.qpBfvwvo.AkOajFd.PiKjuE1IAytQ.:18601:0:60:1:::

xmen@192.168.56.250's password:

Last login: Sat Dec 5 14:57:51 2020 from 192.168.56.1

Create user manually

Copy the existing line and paste in new line

[root@zmpt01 ~]# vi /etc/passwd

spiderman:x:5005:6005::/home/spiderman:/bin/bash

Create group manually

spiderman:x:6005:

Create password maually

[root@zmpt01 ~]# vi /etc/passwd

spiderman:$6$87Fs/vJF$EHqhBznCvyU5w4d3XsL6tfsaB7Q3WcDnf8xVB0.

NwObSnBZo/Sw6KTG.qpBfvwvo.AkOajFd.PiKjuE1IAytQ.:18601:0:60:7:::

Create user home directory manually

[root@zmpt01 home]# mkdir spiderman

Change the permissions for spiderman home directory

[root@zmpt01 home]# chown spiderman:spiderman spiderman

[root@zmpt01 home]# chown 5005:6005 spiderman

Change the permissions either user the name or the id’s

[root@zmpt01 home]# ls -ls

total 0

0 drwxr-xr-x. 2 spiderman spiderman 6 Dec 5 15:16 spiderman

spiderman@192.168.56.250's password:

Last login: Sat Dec 5 15:15:37 2020 from 192.168.56.1

-bash-4.2$ pwd

/home/spiderman

.bashrc - .bash_profile - .bash_history are missing

-bash-4.2$ cp /etc/skel/.bash* .

-bash-4.2$ ls -la

total 12

drwxr-xr-x. 2 spiderman spiderman 62 Dec 5 15:26 .

drwxr-xr-x. 5 root root 53 Dec 5 15:16 ..

-rw-r--r--. 1 spiderman spiderman 18 Dec 5 15:26 .bash_log out

-rw-r--r--. 1 spiderman spiderman 193 Dec 5 15:26 .bash_pro file

-rw-r--r--. 1 spiderman spiderman 231 Dec 5 15:26 .bashrc

Difference between root user and regular user

[root@zmpt01 ~]# < --- # root user

[spiderman@zmpt01 ~]$ < --- $ regular user

SuDO access

SuDO = Super User DO

Super user access – but not full root access.

- It allows regular user to perform taks wich requires admin access

User without SuDO access

[terminator@zmpt01 ~]$ yum install firefox -y

Loaded plugins: fastestmirror

You need to be root to perform this command.

[terminator@zmpt01 ~]$

Informational

[root@zmpt01 ~]# visudo

## Allows people in group wheel to run all commands

%wheel ALL=(ALL) ALL < --- making sure wheel group is not commented out

Grant Access to SuDO

[root@zmpt01 ~]# usermod -aG wheel terminator

[root@zmpt01 ~]# id terminator

uid=1000(terminator) gid=1000(terminator) groups=1000(terminator),10(wheel)

usermod -aG wheel terminator

Command

Adding to group

-a add

-G secondary group

Groupd name/ id

User name/ user id

Usermod

-aG

Wheel

Terminator

Run sudo commands

[terminator@zmpt01 ~]$ sudo yum install firefox -y

[sudo] password for terminator:

Successfully completed

Complete!

Switch to root

[terminator@zmpt01 ~]$ sudo su -

Last login: Sat Nov 28 17:01:34 EST 2020 from 192.168.56.1 on pts/0

[root@zmpt01 ~]#