AWS EC2 & Ubuntu Initial Setup Script

This script automates the initial setup of a new EC2 instance or Ubuntu server. It allows for a secure and streamlined transition from the default system user to a custom setup, including user creation, hostname setting, and SSH key transfer.

Features

• Cross-Compatible: Works on both Amazon Linux and Ubuntu (tested on Ubuntu 24.04+ and Amazon Linux 2023 kernel-6.1).
• User Creation: Adds a new user with a home directory and bash shell.
• Hostname Configuration: Prompts for and sets a new hostname.
• SSH Key Transfer: Copies .ssh keys from the current user to the new user.
• Passwordless Sudo: Grants new user sudo access without requiring a password.
• Preserve Hostname Setting: Modifies /etc/cloud/cloud.cfg to ensure the custom hostname persists after reboot.
• Sudo Check & Auto-Install: Ensures sudo is installed (for minimal Ubuntu/Amazon Linux images).

Usage

1. Clone the Repository

   git clone https://github.com/HezhaKh/ops345.git

2. Navigate to the Script Directory

   cd ./ops345

3. Make the Script Executable

   chmod +x ./setup_aws.sh

4. Run the Script as Root or with Sudo

   sudo ./setup_aws.sh

5. Follow the Prompts

   • Enter a new username (e.g., admin).
   • Enter a custom hostname (e.g., myserver01).
   • Optionally enter a sudoers file name (default is 10-ops345-users).

6. (Optional) Remove the Default EC2 User

   sudo userdel -r ec2-user

Script Breakdown

• Verifies root/sudo privileges before continuing.
• Prompts for and creates a new user.
• Transfers SSH keys from the current user.
• Assigns NOPASSWD:ALL sudo permission to the new user.
• Sets the hostname using hostnamectl.
• Edits /etc/cloud/cloud.cfg to ensure hostname persists across reboots.
• Conditionally installs sudo using apt (Ubuntu) or dnf (Amazon Linux) if not present.

Notes

• The script uses logname to identify the current SSH user (e.g., ubuntu or ec2-user). Make sure you run the script from a valid user shell.
• If the .ssh directory doesn’t exist for the current user, the SSH key copy step will be skipped with a warning.
• You must run this script with sudo or as the root user.

Final Tip

After setup, test logging in as the new user. Once confirmed, you can safely remove the default EC2 or Ubuntu user.