Creating and Managing User Accounts on Your CentOS VPS

#### Prerequisites Before you begin, ensure you have: - A CentOS VPS (This guide is tested with CentOS 8) - A user account with sudo privileges - Basic familiarity with the command line #### Step 1: Create a New User To create a new user, use the `useradd` command followed by the username. For example, to create a user named `john`: ```bash sudo useradd john ``` Set a password for the new user: ```bash sudo passwd john ``` You will be prompted to enter and confirm the new password. #### Step 2: Add User to Sudo Group To grant the new user sudo privileges, add them to the `wheel` group: ```bash sudo usermod -aG wheel john ``` Users in the `wheel` group have sudo access by default on CentOS. #### Step 3: Create a Home Directory for the User The `useradd` command typically creates a home directory automatically. Verify that the home directory exists: ```bash ls /home/john ``` If the home directory does not exist, create it manually: ```bash sudo mkdir /home/john sudo chown john:john /home/john ``` #### Step 4: Set Up SSH Access To allow the new user to access the server via SSH, copy the SSH keys (if applicable): 1. **Create the `.ssh` directory:** ```bash sudo mkdir /home/john/.ssh sudo chown john:john /home/john/.ssh sudo chmod 700 /home/john/.ssh ``` 2. **Add the public key to `authorized_keys`:** ```bash sudo nano /home/john/.ssh/authorized_keys ``` Paste the public key into the file, save, and exit. Set the appropriate permissions: ```bash sudo chown john:john /home/john/.ssh/authorized_keys sudo chmod 600 /home/john/.ssh/authorized_keys ``` #### Step 5: Configure User Shell Settings To change the default shell for a user, use the `chsh` command followed by the shell path. For example, to set the default shell to Bash: ```bash sudo chsh -s /bin/bash john ``` Verify the change: ```bash grep john /etc/passwd ``` #### Step 6: Managing User Permissions To manage user permissions, you can edit the sudoers file using `visudo`: ```bash sudo visudo ``` Add specific permissions for the user under the user privilege specification section: ```plaintext john ALL=(ALL) NOPASSWD: /usr/bin/yum ``` This line allows the user `john` to run `yum` commands without a password prompt. #### Step 7: Lock and Unlock User Accounts To lock a user account, preventing them from logging in: ```bash sudo passwd -l john ``` To unlock the account: ```bash sudo passwd -u john ``` #### Step 8: Delete a User Account To delete a user account along with their home directory, use the `userdel` command with the `-r` flag: ```bash sudo userdel -r john ``` #### Step 9: Monitor User Activity To monitor user activity and login attempts, you can use the `last` command to see the history of user logins: ```bash last john ``` To view the current logged-in users, use: ```bash w ``` #### Step 10: Secure User Accounts For enhanced security, enforce strong passwords and password policies. Edit the `/etc/login.defs` file to set password aging policies: ```bash sudo nano /etc/login.defs ``` Configure settings such as `PASS_MAX_DAYS`, `PASS_MIN_DAYS`, and `PASS_WARN_AGE` to enforce password changes and expiration: ```plaintext PASS_MAX_DAYS 90 PASS_MIN_DAYS 10 PASS_WARN_AGE 7 ``` #### Conclusion You have successfully created and managed user accounts on your CentOS VPS, including user creation, permission management, and security measures. Regularly review and update user permissions and security settings to ensure the integrity and security of your server. **Additional Resources:** - **CentOS Documentation:** [https://www.centos.org/docs/](https://www.centos.org/docs/) - **Linux User Management:** [https://www.linux.org/forums/linux-user-management.148/](https://www.linux.org/forums/linux-user-management.148/) - **Sudoers Manual:** [https://www.sudo.ws/man/1.8.15/sudoers.man.html](https://www.sudo.ws/man/1.8.15/sudoers.man.html)