tirsdag den 30. maj 2023

Linux Command Line Hackery Series - Part 6


Welcome back to Linux Command Line Hackery series, I hope you've enjoyed this series so far and would have learned something (at least a bit). Today we're going to get into user management, that is we are going to learn commands that will help us add and remove users and groups. So bring it on...

Before we get into adding new users to our system lets first talk about a command that will be useful if you are a non-root user.

Command: sudo
Syntax: sudo [options] command
Description: sudo allows a permitted user to execute a command as a superuser or another user.

Since the commands to follow need root privileges, if you are not root then don't forget to prefix these commands with sudo command. And yes you'll need to enter the root password in order to execute any command with sudo as root.

Command: useradd
Syntax: useradd [options] username
Description: this command is used for creating new user but is kinda old school.
Lets try to add a new user to our box.
[Note: I'm performing these commands as root user, you'll need root privileges to add a new user to your box. If you aren't root then you can try these commands by prefixing the sudo command at the very beginning of these command like this sudo useradd joe. You'll be prompted for your root password, enter it and you're good to go]

useradd joe

To verify that this command has really added a user to our box we can look at three files that store a users data on a Linux box, which are:

/etc/passwd -> this file stores information about a user separated by colons in this manner, first is login name, then in past there used to be an encrypted password hash at the second place however since the password hashes were moved to shadow file now it has a cross (x) there, then there is user id, after it is the user's group id, following it is a comment field, then the next field contains users home directory, and at last is the login shell of the user.

/etc/group  -> this file stores information about groups, that is id of the group and to which group an user belongs.

/etc/shadow -> this file stores the encrypted password of users.

Using our command line techniques we learned so far lets check out these files and verify if our user has been created:

cat /etc/passwd /etc/group /etc/shadow | grep joe



In the above screenshot you can notice an ! in the /etc/shadow, this means the password of this user has not been set yet. That means we have to set the password of user joe manually, lets do just that.

Command: passwd
Syntax: passwd [options] [username]
Description: this command is used to change the password of user accounts.
Note that this command needs root privileges. So if you are not root then prefix this command with sudo.

passwd joe



After typing this command, you'll be prompted password and then for verifying your password. The password won't show up on the terminal.
Now joe's account is up and running with a password.

The useradd command is a old school command, lets create a new user with a different command which is kinda interactive.

Command: adduser
Syntax: adduser [options] user
Description: adduser command adds a user to the system. It is more friendly front-end to the useradd command.

So lets create a new user with adduser.

adduser jane



as seen in the image it prompts for password, full name and many other things and thus is easy to use.

OK now we know how to create a user its time to create a group which is very easy.

Command: addgroup
Syntax: addgroup [options] groupname
Description: This command is used to create a new group or add an existing user to an existing group.

We create a new group like this

addgroup grownups



So now we have a group called grownups, you can verify it by looking at /etc/group file.
Since joe is not a grownup user yet but jane is we'll add jane to grownups group like this:

addgroup jane grownups



Now jane is the member of grownups.

Its time to learn how to remove a user from our system and how to remove a group from the system, lets get straight to that.

Command: deluser
Syntax: deluser [options] username
Description: remove a user from system.

Lets remove joe from our system

deluser joe

Yes its as easy as that. But remember by default deluser will remove the user without removing the home directory or any other files owned by the user. Removing the home directory can be achieved by using the --remove-home option.

deluser jane --remove-home

Also the --remove-all-files option removes all the files from the system owned by the user (better watch-out). And to create a backup of all the files before deleting use the --backup option.

We don't need grownups group so lets remove it.

Command: delgroup
Syntax: delgroup [options] groupname
Description: remove a group from the system.

To remove grownups group just type:

delgroup grownups



That's it for today hope you got something in your head.

Continue reading


  1. Hacker Tools
  2. New Hack Tools
  3. Pentest Tools
  4. Hack Tools
  5. Pentest Tools Tcp Port Scanner
  6. Top Pentest Tools
  7. Hack Tool Apk
  8. Best Hacking Tools 2019
  9. Hacker Tools Apk Download
  10. Hacker Security Tools
  11. Github Hacking Tools
  12. Tools For Hacker
  13. Black Hat Hacker Tools
  14. Hacker Tools 2019
  15. Pentest Tools Alternative
  16. Pentest Tools Windows
  17. Hacker Tools Hardware
  18. Pentest Tools Website Vulnerability
  19. Hacking App
  20. Hacker Tools Apk Download
  21. Hacking Tools Online
  22. Hacking Tools Windows 10
  23. Beginner Hacker Tools
  24. Hacking Tools Windows 10
  25. Hack Tools For Games
  26. Hack Tools Download
  27. Hack Tools For Ubuntu
  28. Hacking Tools For Pc
  29. Bluetooth Hacking Tools Kali
  30. Hacking Tools For Windows 7
  31. Hack Website Online Tool
  32. Hacker Tools Online
  33. Pentest Tools Bluekeep
  34. Pentest Tools For Windows
  35. Install Pentest Tools Ubuntu
  36. Pentest Tools Subdomain
  37. Bluetooth Hacking Tools Kali
  38. How To Make Hacking Tools
  39. Hacker Tools For Mac
  40. Best Pentesting Tools 2018
  41. Hacking Tools Download
  42. Hack Tools For Pc
  43. Best Pentesting Tools 2018
  44. Pentest Tools
  45. Hacking Tools Free Download
  46. Game Hacking
  47. Hacker Tools Free
  48. Kik Hack Tools
  49. Pentest Tools List
  50. Hacker Tools 2019
  51. Install Pentest Tools Ubuntu
  52. Hack Tools For Windows
  53. Install Pentest Tools Ubuntu
  54. Pentest Tools Tcp Port Scanner
  55. Hacking Tools Hardware
  56. Pentest Tools Github
  57. Hacking Tools For Mac

Ingen kommentarer:

Send en kommentar