Debian POST Install Configuration

After installing Debian, the following setup is recommended.

Make User Admin with sudo

Install useful management packages:

apt install -y net-tools sudo curl

Then add the initial user to the sudo group:

adduser [username] sudo

Disable root User Login

Now that you have an administrative sudo user, you can disable the root user login altogether.

Edit /etc/passwd and change the root line as shown below:

root:x:0:0:root:/root:/usr/sbin/nologin

After that, lock the root user:

passwd -l root

A user with a locked password can’t login: passwd -l puts a ! character in front of the password hash in /etc/shadow.

Passwordless SSH Configuration

Generate SSH Key

If you don’t have a key, generate one:

ssh-keygen -t rsa

This creates ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub.

Test registering the key (dry-run with -n):

ssh-copy-id -n -i ~/.ssh/id_rsa username@server.ip

When everything looks good, remove -n to register:

ssh-copy-id -i ~/.ssh/id_rsa username@server.ip

Make sudo Passwordless

Caution: Use with care — this approach is for passwordless systems that use SSH key authentication only.

Edit the sudo config:

visudo

Add [username] ALL=(ALL) NOPASSWD:ALL to allow sudo without re-entering password:

username ALL=(ALL)   NOPASSWD:ALL

Or use this one-liner if you already have sudo privileges:

sudo bash -c "echo '$USER ALL=(ALL) NOPASSWD:ALL' > /etc/sudoers.d/$USER && chmod 0440 /etc/sudoers.d/$USER"

Lock Password-Based Login

Lock the user account from password login:

passwd -l username

Welcome to passwordless.