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Debian netinst installation

Install Debian from the netinst image on a HolyCloud dedicated server via IPMI, partitioning, and initial hardening.

~15 min read Intermediate #debian #netinst #installation #dedicated

Debian netinst installation

The Debian netinst image downloads packages during installation — ideal for a minimal dedicated server then customized. HolyCloud often allows ISO mount via IPMI or a similar panel reinstall.

Prerequisites

  • IPMI/KVM access (see console and iLO/iDRAC guides)
  • ISO debian-12.x.x-amd64-netinst.iso (cdimage.debian.org)
  • Public IP, gateway, netmask, DNS
  • Partition plan (GPT, EFI if UEFI)
  • Backup of existing data

Download and verify the ISO

wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-12.9.0-amd64-netinst.iso
wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/SHA256SUMS
sha256sum -c SHA256SUMS 2>&1 | grep netinst

Mount ISO via IPMI

  1. Connect to the BMC (HolyCloud panel).
  2. Virtual Media → CD-ROM → select netinst ISO.
  3. One-shot boot to CD/DVD.
  4. KVM console: Debian graphical or text installer.

Installer steps

------- ----------------------
Language / keyboard EN / us
Hostname srv01.domaine.tld
Domain domaine.tld
Root password Strong + vault or SSH key only later
User Non-root sudo account for daily admin
Partitioning Guided - use entire disk or LVM for local snapshots
Software Uncheck desktop; check SSH server and standard system utilities
Mirror deb.debian.org (optional French mirror)

Manual partitioning (example)

------------------ -------- -----
/boot or /boot/efi 512 Mi – 1 Gi ext4 / FAT32 EFI
swap 0–8 Gi (or zram later) swap
/ remainder ext4 or xfs

On NVMe + hardware RAID, the installer often sees a single volume md127 or sda.

Network during install

Manual mode if multiple VLANs:

  • IP: HolyCloud-provided address
  • Netmask: /24 or /32 per sheet
  • Gateway: indicated gateway
  • DNS: 1.1.1.1, 8.8.8.8 or client DNS

End of installation

Unmount virtual ISO before reboot:

  • IPMI → unmount virtual media
  • Boot order: hard disk first

First SSH:

ssh root@IP_PUBLIQUE
# or
ssh admin@IP_PUBLIQUE

Essential post-install

apt update && apt full-upgrade -y
apt install -y sudo vim curl wget git ufw fail2ban

Sudo user:

usermod -aG sudo admin

SSH key (from your workstation):

ssh-copy-id admin@IP_PUBLIQUE

Disable root password login if strict policy — /etc/ssh/sshd_config:

PermitRootLogin prohibit-password
PasswordAuthentication no
systemctl restart sshd

Sources and backports

/etc/apt/sources.list (Debian 12 bookworm):

deb http://deb.debian.org/debian bookworm main contrib non-free-firmware
deb http://security.debian.org/debian-security bookworm-security main
deb http://deb.debian.org/debian bookworm-updates main
apt update

NTP and timezone

timedatectl set-timezone Europe/Paris
apt install -y chrony
timedatectl status

Initial firewall

ufw default deny incoming
ufw allow 22/tcp
ufw allow 80,443/tcp
ufw enable

Failover IP (if applicable)

Add aliases after stable install — see « Configure a failover IP » guide.

Install troubleshooting

---------- -------
Installer does not see disk RAID driver — AHCI in BIOS or module
No network VLAN trunk, cable, wrong gateway

Debian rescue mode

From netinst, Rescue mode mounts partitions for repair without reinstalling.

Need help?

HolyCloud can confirm network layout (MAC, bonding) and UEFI/Legacy compatibility for your dedicated reference.