2.3. Configuring sudo Access-RedHat

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/2/html/Getting_Started_Guide/ch02s03.html

The sudo command offers a mechanism for providing trusted users with administrative access to a system without sharing the password of the root user. When users given access via this mechanism precede an administrative command with sudo they are prompted to enter their own password. Once authenticated, and assuming the command is permitted, the administrative command is executed as if run by the rootuser.

Follow this procedure to create a normal user account and give it sudo access. You will then be able to use the sudo command from this user account to execute administrative commands without logging in to the account of the root user.

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Procedure 2.2. Configuring sudo Access

1. Log in to the system as the root user.
2. Create a normal user account using the useradd command. Replace USERNAME with the user name that you wish to create.

   # useradd USERNAME

3. Set a password for the new user using the passwd command.

   # passwd USERNAME
   Changing password for user USERNAME.
   New password:
   Retype new password:
   passwd: all authentication tokens updated successfully.

4. Run the visudo to edit the /etc/sudoers file. This file defines the policies applied by the sudocommand.

   # visudo

5. Find the lines in the file that grant sudo access to users in the group wheel when enabled.

   ## Allows people in group wheel to run all commands
   # %wheel        ALL=(ALL)       ALL

6. Remove the comment character (#) at the start of the second line. This enables the configuration option.
7. Save your changes and exit the editor.
8. Add the user you created to the wheel group using the usermod command.

   # usermod -aG wheel USERNAME

9. Test that the updated configuration allows the user you created to run commands using sudo.
   1. Use the su to switch to the new user account that you created.

      # su USERNAME -

   2. Use the groups to verify that the user is in the wheel group.

      $ groups
      USERNAME wheel

   3. Use the sudo command to run the whoami command. As this is the first time you have run a command using sudo from this user account the banner message will be displayed. You will be also be prompted to enter the password for the user account.

      $ sudo whoami
      We trust you have received the usual lecture from the local System
      Administrator. It usually boils down to these three things:
      
          #1) Respect the privacy of others.
          #2) Think before you type.
          #3) With great power comes great responsibility.
      
      [sudo] password for USERNAME:
      root

      The last line of the output is the user name returned by the whoami command. If sudo is configured correctly this value will be root.

You have successfully configured a user with sudo access. You can now log in to this user account and use sudo to run commands as if you were logged in to the account of the root user.