systemd-first-boot-script

Introduction

systemd-first-boot-script is a set of scripts to configure GNU+Linux systems at first boot.

Purpose

Setting up pre-configured virtual machines or GNU+Linux system is easy. Sharing them to other people involves sharing credentials, which is not a good thing from security point of view.

This set of scripts allows running several configuration programs in order to:

• reset SSH server keys
• change root password
• change main user password (which is supposed to be in sudoers group)
• create a new user within sudoers group
• change machine name
• display connection information (or anything else)

A skeleton is provided to create one's own scripts.

Deployment

The target machine should have a working ssh server.

The preparation of script is done on another machine (local machine e.g.) from which the script can be sent using a synchronization script.

Actually, this prevent from installing git on the target machine (which is not wanted for some systems).

Installation and configuration

Clone this directory on your local machine.

Configuration

Copy sync.data.example to sync.data :

cp sync.data.example sync.data

Edit sync.data with credential for target machine (using ssh keys is recommended but not mandatory).

Deployment

Remote copy

Run synchronization script from local machine:

./dosync.sh

All files should be copied on the target machine

On target machine

Everything here should be run as super-user (or with sudo).

From the synced directory, run the deployment script:

cd install-systemd-first-boot-script # or the name you chose in sync.data
./deploy

All files are copied to /etc/first-boot/

Select the files to be executed in /etc/first-boot/scripts (here is selected a subset of available scripts) :

cd /etc/first-boot/scripts
chmod -x *
chmod +x 01-renew-ssh-keys 02-password 03-user-password 50-hostname

Check the permissions are correct (only scripts with execution permission will be run):

ls -l /etc/first-boot/scripts
-rwxr-xr-x@ 1 root  root   625 10 oct 10:59 01-renew-ssh-keys
-rwxr-xr-x@ 1 root  root   581 10 oct 10:59 02-password
-rwxr-xr-x@ 1 root  root   662 10 oct 11:01 03-user-password
-rw-r--r--@ 1 root  root  1114 10 oct 11:08 04-create-default-user
-rwxr-xr-x  1 root  root   660 10 oct 11:09 50-hostname
-rw-r--r--@ 1 root  root   732 11 oct 15:42 90-display-ip
-rw-r--r--@ 1 root  root   755 10 oct 10:59 skeleton

Now the machine is ready to be rebooted.

Test

You can test by rebooting the machine.

You will have to answer to all question (it is not possible to kill process). So use passwords you know.

Once is is OK for you, re-run the deployment script (this will reset the flag that indicates the script was already run):

cd install-systemd-first-boot-script # or the name you chose in sync.data
./deploy

And check once again the permissions in /etc/first-boot/scripts (just to be sure, even they should not have been changed)

You can now delete the installation directory (which could be recreated using the dosync.sh script from your local machine :

cd ..
rm -r install-systemd-first-boot-script

Use it

Strong passwords

Don't forget to use strong passwords on your systems

Share your work

Once ready, shutdown the system and provide it to the person who will use it: this person will have to set its own passwords at first boot.

References

• How to start a script on tty instead of asking for login in systemd? - Unix & Linux Stack Exchange
• ubuntu - Run script on first boot - Server Fault
• How To Use Systemctl to Manage Systemd Services and Units | DigitalOcean
• How to Create and Run New Service Units in Systemd Using Shell Script