Debian Post Install

Enable contrib and non-free sources

Using the terminal, edit the following file, add the “contrib” and “non-free” sources, or replace with these lines:

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

Enable bookworm backports (it works for Trixie as well)

Again, using the terminal, edit the file /etc/apt/sources.list and add the following lines:

# bookworm-backports
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

Update the package manager
```
sudo apt update
```

Enable 32bit packages

sudo dpkg --add-architecture i386 && sudo apt update

Enable Flatpak support

sudo apt install flatpak

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

sudo apt install gnome-software-plugin-flatpak

Install and configure Virtual Manager

sudo apt install qemu-system libvirt-daemon-system virt-manager

Using vim (or any other text editor), open libvirtd.conf and enable these two lines:

sudo vim /etc/libvirt/libvirtd.conf

unix_sock_group = "libvirt"
unix_sock_rw_perms = "0770"

Start and enable the libvirtd service:

sudo systemctl enable libvirtd && sudo systemctl start libvirtd

Add your user to the libvirt group by typing this command:

sudo usermod -a -G libvirt $(whoami)

Start the default network and enable autostart:

sudo virsh net-start default && sudo virsh net-autostart --network default

Fix slow shutdown

Edit system.conf and change the default value from 90s to 15s (or 10s):
```
sudo vim /etc/systemd/system.conf
```
```
DefaultTimeoutStopSec=15s
```

Remove all pre-installed GNOME games

Run:

sudo apt purge iagno lightsoff four-in-a-row gnome-robots pegsolitaire gnome-2048 hitori gnome-klotski gnome-mines gnome-mahjongg gnome-sudoku quadrapassel swell-foop gnome-tetravex gnome-taquin aisleriot gnome-chess five-or-more gnome-nibbles tali
sudo apt autoremove

Or just run:

sudo apt purge gnome-games

Fix broken QT application theme

Follow the steps covered under the “Fix Broken QT Themes on Debian” guide.
Font configuration

Follow the steps by clicking here.
Set up firewall

Click here and follow the steps.