Red Hat System Administration I

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Lab: Managing Users and Groups, Permissions and Processes

In this review, you will manage user and group accounts, set permissions on files and directories, and manage processes.

Outcomes

You should be able to:

  • Manage users and groups.

  • Set permissions on files and directories.

  • Remove processes that are consuming too much CPU.

Log in to workstation as student using student as the password.

On workstation, run lab rhcsa-rh124-review2 start to start the comprehensive review. This script runs a process that consumes the maximum CPU resources and creates the necessary files to set up the environment correctly. 

[student@workstation ~]$ lab rhcsa-rh124-review2 start

Instructions

Accomplish the following tasks on serverb to complete the exercise.

  • Terminate the process that is currently using the most CPU time.

  • Create a new group called database that has the GID 50000.

  • Create a new user called dbuser1 that uses the group database as one of its secondary groups. The initial password of dbuser1 should be set to redhat. Configure the user dbuser1 to force a password change on its first login. The user dbuser1 should be able to change its password after 10 days since the day of the password change. The password of dbuser1 should expire in 30 days since the last day of the password change.

  • Configure the user dbuser1 to use sudo to run any command as the superuser.

  • Configure the user dbuser1 to have a default umask of 007.

  • The permissions on /home/student/grading/review2 should allow the group members of database and the user student to access the directory and create contents in it. All other users should have read and execute permissions on the directory. Also, ensure that users are only allowed to delete files they own from /home/student/grading/review2 and not files belonging to others.

  1. Terminate the process that is currently using the most CPU time.

    1. From workstation, open an SSH session to serverb as student. 

      [student@workstation ~]$ ssh student@serverb
...output omitted...
[student@serverb ~]$

    2. Use the top command to view the real-time system status. 

      [student@serverb ~]$ top

    3. From the interactive interface of top, pay attention to the %CPU column and confirm that there is a process called dd, consuming the most CPU resources. 

      ...output omitted...
 PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
2303 student   20   0  217048    944    876 R  99.7   0.1 100:11.64 dd
...output omitted...

      Notice the process dd with the PID 2303 in the preceding output, which is consuming the majority of CPU resources, at 99.7%. The PID and the percentage of CPU resource consumption may vary in your system.

    4. From the interactive interface of top, type k to kill the process dd with PID 2303, as you determined in the preceding step. If the default PID shown in the prompt matches that of the process consuming the majority of CPU resources, press the Enter key on the keyboard. If it does not match, specify the PID interactively. 

      ...output omitted...
PID to signal/kill [default pid = 2303] Enter
...output omitted...

    5. Use the default signal SIGTERM to terminate the process. 

      ...output omitted...
Send pid 2833 signal [15/sigterm] Enter
...output omitted...

    6. From the interactive interface, press the q key on the keyboard to quit top.

  2. Create a new group called database with GID 50000.

    1. Switch to the user root. 

      [student@serverb ~]$ sudo su -
[sudo] password for student: student
[root@serverb ~]#

    2. Use the groupadd command to create a new group called database with GID 50000. 

      [root@serverb ~]# groupadd -g 50000 database

  3. Create a new user called dbuser1 with group database as one of its secondary groups. Set the initial password of dbuser1 to redhat. Configure the user dbuser1 to force a password change upon first login. The user dbuser1 should be able to change its password after 10 days since the last day of the password change. The password of dbuser1 should expire in 30 days since the last day of the password change.

    1. Use the useradd command to create a new user called dbuser1 that uses the group database as one of its secondary groups. 

      [root@serverb ~]# useradd -G database dbuser1

    2. Use the passwd command to set the password of dbuser1 to redhat. 

      [root@serverb ~]# passwd dbuser1
Changing password for user dbuser1.
New password: redhat
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: redhat
passwd: all authentication tokens updated successfully.

    3. Use the chage command to force dbuser1 to change its password on first login. 

      [root@serverb ~]# chage -d 0 dbuser1

    4. Use the chage command to set the minimum age of the password of dbuser1 to 10 days. 

      [root@serverb ~]# chage -m 10 dbuser1

    5. Use the chage command to set the maximum age of the password of dbuser1 to 30 days. 

      [root@serverb ~]# chage -M 30 dbuser1

  4. Create the file /etc/sudoers.d/dbuser1 to configure dbuser1 so that the user can use sudo to run any command as the superuser. You may use the vim /etc/sudoers.d/dbuser1 command to create the file. The /etc/sudoers.d/dbuser1 should contain the following content. 

    1. dbuser1 ALL=(ALL) ALL

  5. Configure the user dbuser1 to have a default umask of 007.

    1. Switch to the user dbuser1. 

      [root@serverb ~]# su - dbuser1
[dbuser1@serverb ~]$

    2. Append the line umask 007 to the files /home/dbuser1/.bash_profile and /home/dbuser1/.bashrc. 

      [dbuser1@serverb ~]$ echo "umask 007" >> .bash_profile
[dbuser1@serverb ~]$ echo "umask 007" >> .bashrc

    3. Exit the dbuser1 user's shell. 

      [dbuser1@serverb ~]$ exit
logout
[root@serverb ~]#

  6. Create a new directory called /home/student/grading/review2 with student and database as its owning user and group respectively. Configure the permissions on that directory so that any new file in it inherits database as its owning group irrespective to the creating user. The permissions on /home/student/grading/review2 should allow the group members of database and the user student to access the directory and create contents in it. All other users should have read and execute permissions on the directory. Also, ensure that the users are only allowed to delete the files, they own, from /home/student/grading/review2 and not others' files.

    1. Use the mkdir command to create /home/student/grading/review2. 

      [root@serverb ~]# mkdir /home/student/grading/review2

    2. On the /home/student/grading/review2, use the chown command to set student and database as the owning user and group respectively. 

      [root@serverb ~]# chown student:database /home/student/grading/review2

    3. Use the chmod command to apply the SetGID special permission on /home/student/grading/review2. 

      [root@serverb ~]# chmod g+s /home/student/grading/review2

    4. Use the chmod command to apply the permission mode 775 on /home/student/grading/review2. 

      [root@serverb ~]# chmod 775 /home/student/grading/review2

    5. Use the chmod command to apply the stickybit special permission on /home/student/grading/review2. 

      [root@serverb ~]# chmod o+t /home/student/grading/review2

    6. Exit the root user's shell. 

      [root@serverb ~]# exit
logout
[student@serverb ~]$

    7. Log out of serverb. 

      [student@serverb ~]$ exit
logout
Connection to serverb closed.
[student@workstation ~]$

Evaluation

On workstation, run the lab rhcsa-rh124-review2 grade command to confirm success of this exercise. 

[student@workstation ~]$ lab rhcsa-rh124-review2 grade

Finish

On workstation, run lab rhcsa-rh124-review2 finish to complete the comprehensive review. This script terminates the process and deletes the files and directories created during the start of the comprehensive review and ensures that the environment on serverb is clean. 

[student@workstation ~]$ lab rhcsa-rh124-review2 finish

This concludes the comprehensive review.

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Revision: rh124-8.2-df5a585