Debian 12 Post Install Guide

Things to do after installing Debian 12

Non-free repositories

• The default installation of Debian 12 stable from https://www.debian.org/ comes with free repositories
• To add non-free repositories, add non-free contrib to each line in /etc/apt/sources.list
• sudo nano /etc/apt/sources.list

deb http://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware

deb http://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware
deb-src http://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware

deb http://deb.debian.org/debian/ bookworm-updates main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian/ bookworm-updates main contrib non-free non-free-firmware

• sudo apt update && sudo apt upgrade

Install flatpak and flathub repositories

• To install flatpak applications you must install flatpak first:

sudo apt install flatpak -y

• Then add the flathub repositories:

flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

• For Gnome:

sudo apt install gnome-software-plugin-flatpak -y

• For KDE Plasma:

sudo apt install plasma-discover-backend-flatpak -y

• sudo reboot

Remove Firefox ESR and install flatpak Browser

• The default version of Firefox in Debian 12 is Firefox ESR (Extended Support Release), which may be behind most updates, you can remove and install your favorite browser with:

sudo apt remove firefox-esr

• To install Mozilla Firefox's flatpak:

flatpak install flathub org.mozilla.firefox

• To install Google Chrome's flatpak:

flatpak install flathub com.google.Chrome

NVIDIA Drivers

• If you have an NVIDIA GPU, you can install the drivers with

sudo apt install nvidia-driver -y

• Wait at least 5 min for the driver to build, then reboot
• sudo reboot

Multimedia Codecs

• Install multimedia codecs to stream videos and other media content

sudo apt install libavcodec-extra vlc -y

Firewall

• Setting up a firewall on Debian can be done using UFW (Uncomplicated Firewall)
• Set up firewall with:
• sudo apt install ufw -y
• sudo ufw enable
• sudo ufw status

Swapfile

• If you didn't create a swap partition, you can create a /swapfile, the following example is for adding a 7.5GB /swapfile, recommended for systems with 8GB of RAM:

free -h
sudo swapon --show

sudo dd if=/dev/zero of=/swapfile bs=1M count=7680
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo bash -c 'echo "/swapfile swap swap defaults 0 0" >> /etc/fstab'

free -h
sudo swapon --show

• Modern recommendations vary based on use cases:
• Equal to RAM (1x RAM): common for general-purpose systems, ensuring adequate swap space without overcommitting storage
• Twice RAM (2x RAM): more useful for systems with low RAM (<4GB) or for applications requiring significant swap (e.g., hibernation, heavy multitasking)
• Less than RAM (<1x RAM): often fine for high-RAM systems (16GB+), where swap is rarely needed

Backport support

• If you want to use backport packages, add the following lines at the end of /etc/apt/sources.list
• sudo apt nano /etc/apt/sources.list

# bookworm-backport
deb http://deb.debian.org/debian bookworm-backports main contrib non-free
deb-src http://deb.debian.org/debian bookworm-backports main contrib non-free

• sudo apt update && sudo apt upgrade

Switch to Debian 12 Testing branch

• If you want to use the Debian 12 testing branch, replace bookworm with testing in /etc/apt/sources.list
• sudo nano /etc/apt/sources.list

deb http://deb.debian.org/debian/ testing main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian/ testing main contrib non-free non-free-firmware

deb http://security.debian.org/debian-security testing-security main contrib non-free non-free-firmware
deb-src http://security.debian.org/debian-security testing-security main contrib non-free non-free-firmware

deb http://deb.debian.org/debian/ testing-updates main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian/ testing-updates main contrib non-free non-free-firmware

• sudo apt update && sudo apt upgrade
• Same if you use backports:

# testing-backport
deb http://deb.debian.org/debian testing-backports main contrib non-free
deb-src http://deb.debian.org/debian testing-backports main contrib non-free

• sudo apt update && sudo apt upgrade