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FlatlinerAtheist | CLI-NERDS
FlatlinerAtheist | CLI-NERDS

Posted on Originally published at clinerds.com

How to Install Debian 11 (Bullseye): USB, Partitioning, and First Boot

#linux #debian #installation #server

Debian 11 "Bullseye" arrived in 2021 and quickly became a server favorite: predictable, stable, and boring in the best possible way. These days newer releases exist (Debian 12 and 13), but there are still good reasons to install Bullseye — legacy application support, reproducing a production environment, or older hardware that a newer stack doesn't like.

Fair warning before you start: Bullseye's regular security support ended in August 2024, so it now only receives limited LTS/ELTS updates. For anything new and internet-facing, install a current release instead. For a VM or lab machine, this guide works fine.

What you need

  • A PC, VM, or server you can erase (installation wipes the target disk)
  • A USB stick (2 GB+) or the ISO attached to your VM
  • The netinst ISO from the Debian archive: cdimage.debian.org → "older releases" → 11.x → debian-11.x.x-amd64-netinst.iso

Verify the download before trusting it:

sha256sum debian-11.11.0-amd64-netinst.iso
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Compare the hash with the SHA256SUMS file in the same archive directory. It takes five seconds and rules out a corrupted or tampered image.

Create the bootable USB

From Linux, the reliable way is dd — triple-check the device name with lsblk first, because the wrong target erases the wrong disk:

sudo dd if=debian-11.11.0-amd64-netinst.iso of=/dev/sdX bs=4M status=progress && sync
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On Windows, use Rufus or balenaEtcher and select the same ISO. (More detail in our dd live-USB guide.)

Boot and start the installer

Boot from the USB (usually F12, F11, or Esc for the boot menu) and choose Graphical install — or plain Install on older hardware.

The installer walks you through the usual steps:

  1. Language, location, keyboard — pick what matches you
  2. Network — set a hostname like debian-lab; domain can stay blank for a home machine
  3. Users — set the root password (or leave it blank to get sudo configured instead, which is the friendlier choice), then create your normal user
  4. Disk partitioning — for a VM or dedicated machine, "Guided – use entire disk" with "All files in one partition" is fine. On a real server, consider separate /home, /var, and /tmp
  5. Write changes to disk — this is the point of no return; confirm only if you selected the right drive

Packages and desktop

The netinst downloads packages during installation, so stay online. When the package manager asks, pick a nearby mirror.

At the software selection screen:

  • Desktop environment — GNOME is the default; Xfce or LXQt are lighter for old hardware. For a server, uncheck desktop entirely
  • SSH server — tick this for any headless or remote machine
  • Standard system utilities — keep selected

Finally install the GRUB bootloader to the same disk you installed to, reboot, and remove the USB.

First boot checklist 

sudo apt update && sudo apt full-upgrade -y
sudo apt install -y curl wget vim htop ufw
ip a          # confirm you have an IP address
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Enable the firewall if the machine faces a network (sudo ufw enable after allowing SSH), and you're done. Bullseye may be old, but as a stable lab platform it still does exactly what Debian has always promised: it installs, it boots, and it stays out of your way.

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