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

| Step | Dedicated server recommendation |

|-------|----------------------|

| 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)

| Mount point | Size | FS |

|------------------|--------|-----|

| /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

| Problem | Hint |

|----------|-------|

| Installer does not see disk | RAID driver — AHCI in BIOS or module |

| No network | VLAN trunk, cable, wrong gateway |

| Reboot loop on ISO | Unmount virtual CD |

| Grub rescue | Reinstall grub from Debian rescue |

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.