How to use instance customization scripts to customize the administrator account of an instance

The content of this article is about how to use the instance custom script to customize the administrator account of the instance. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Customized instance administrator account

Instance custom script is a script provided by Alibaba Cloud ECS for users to customize instance startup behavior. For details, please refer to Alibaba Cloud online help Documentation: Instance custom data.

This document takes a Linux instance as an example to explain how you should use the instance customization script to customize the administrator account of the instance when creating an instance. You can also use scripts to customize administrator accounts for Windows instances.

Scenario

When purchasing an ECS instance, if you want to achieve the following effects, you need to use an instance custom script.

Do not use the default root user that comes with the ECS instance as the administrator. You can customize the specific disabling method and degree in the instance customization script.

Create a new administrator account and customize the username.

The newly created administrator account only uses the SSH key pair for remote login when managing the instance, and does not use the user password.

If this user needs to perform operations related to administrator privileges, he can use sudo to escalate privileges without a password.

Configuration method

You can follow the steps below to achieve the above scenario requirements.

Log in to the Alibaba Cloud ECS console and create an instance with the following configuration:

Network type: VPC network

Instance specification: I/O optimized instance

Mirror: Public mirror CentOS 7.2

Enter the following content in the custom data input box on the creation page:

#!/bin/sh
useradd test
echo "test   ALL=(ALL)        NOPASSWD:ALL" | tee -a /etc/sudoers
mkdir /home/test/.ssh
touch /home/test/.ssh/authorized_keys
echo  ssh-rsa

Note:

The first line must be # !/bin/sh, no spaces in front.

There should be no extra spaces or carriage returns in the entire text.

The key in the last line is your public key, which you can customize.

If you need to make other configurations, you can add them directly in the script.

The sample script is limited to CentOS 7.2 images. For other images, please make custom modifications according to the operating system type.

Select Post-Creation Settings in Security Settings.

After completing the above configuration, click Buy Now and follow the instructions on the page to activate an instance.

After the instance purchase is completed, you can use the customized test user to log in to the instance through the SSH private key. You can also use sudo to escalate privileges and perform various operations that require administrator permissions, as shown in the figure. Example shown.

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