FreezeOS

Secure.Immutable.Fleet-Managed

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Built for the Edge

Every component engineered for zero-trust environments where reliability is non-negotiable.

Immutable Root

Read-only squashfs base with a persistent overlay. The core system cannot be modified at runtime — only via verified OTA updates.

A/B System Updates

Dual system slots enable zero-downtime OTA updates. Automatic rollback after 3 failed boot attempts protects against bad updates.

Full-Disk Encryption

AES-XTS with 512-bit keys on every partition. Server tokens unlock system; user PIN derives keys for personal data via PBKDF2.

Fleet Management

Central enrollment, provisioning, and health monitoring. Manage thousands of devices from a single API with revoke and suspend controls.

Hardware Diagnostics

17+ component tests covering CPU, GPU, storage, memory, and network. Health scoring from 0–100 with automated reporting to fleet.

Recovery Modes

Network recovery re-provisions from fleet server. Safe mode bypasses overlay. Manual rollback reverts to previous system slot.

FreezeLog

Remote debug sharing via encrypted HTTP. Capture boot logs, install traces, and system diagnostics — streamed to your log receiver.

Tron Desktop

Custom XFCE theme with cyan glow borders, wireframe icons, compositor effects, and a purpose-built wallpaper. Beauty meets function.

Security Deep-Dive

Every byte on disk is encrypted. Two independent key domains isolate system integrity from user privacy.

9-Partition Layout

ESP
512 MB • FAT32
EFI Boot
/boot
1 GB • ext4
Kernels, configs, tokens
System A  ↔  System B
8 GB each • LUKS • Server-key unlock
Immutable squashfs • A/B dual-slot
Apps
4–12 GB • LUKS
Persistent overlay upper
App Data
4–12 GB • LUKS
PIN-derived key
User Storage
Remainder • LUKS • PIN-derived key
/home — personal data
Swap
RAM-based • LUKS
PIN-derived key
BIOS Boot
2 MB
Legacy grub
Server-key partitions PIN-derived partitions
AES-XTS-512
Disk Encryption
600,000
PBKDF2 Iterations
RSA-4096
Device Certificates
HMAC-SHA256
Token Signing

Boot Authentication Flow

01

Token Validation

System token read from /boot, HMAC-SHA256 signature verified, expiry checked. Expired tokens accepted for key extraction; invalid tokens halt boot.

02

LUKS Decrypt

Server-provided AES key extracted from token payload. System partition unlocked via LUKS. On failure, recovery mode initiated.

03

Integrity Verify

SHA-256 hash of squashfs image compared against signed manifest. Mismatch triggers automatic rollback to alternate slot.

04

Overlay Mount

Read-only squashfs as lower, apps partition as persistent upper. User config and PAM hooks injected. switch_root to systemd.

05

PIN Unlock

User enters PIN at LightDM login. PBKDF2-HMAC-SHA256 derives 64-byte key from PIN + certificate fingerprint + salt. Unlocks data, appdata, and swap.

Factor 1: Server Token

Fleet-issued, time-limited token contains encrypted LUKS key. Automatic at boot — no user interaction required. Unlocks system and apps partitions.

+

Factor 2: User PIN

Knowledge factor entered at login. Combined with device certificate fingerprint via PBKDF2 to derive unique encryption key for personal data.

Command Your Fleet

Enroll, provision, monitor, and update every device from a single control plane.

Enrollment Pipeline

Boot ISO on target device
Run hardware diagnostics
Register with fleet server
Receive tokens + signed cert
Partition & install OS
Device online & checking in

Dashboard Controls

Enroll new devices
Revoke compromised nodes
Suspend & re-provision
View health cards (0–100)
Push OTA updates
Monitor checkin history

OTA Update Pipeline

Download squashfs image
SHA-256 integrity verify
Write to inactive slot (B)
Flip A/B active slot
Reboot into new system
Auto-rollback if 3 failures

Token Lifecycle

System Token7-day expiry
Apps Token30-day expiry

Tokens auto-refresh on device checkin. Expired tokens still decrypt (key is valid) — only tampered tokens are rejected. Revoked devices get empty token response, locking system on next boot.

Under the Hood

A vertically-integrated boot chain from GRUB to desktop, engineered for integrity at every layer.

Boot Flow

GRUB EFI
initramfs
Token Validate
LUKS Decrypt
SHA-256 Verify
Overlay Mount
switch_root
systemd
LightDM
PIN Unlock
Desktop

A/B Slot Design

Active
Slot A

version: 2.9.30
verified: true
boot_attempts: 0
status: running

Slot B

version: 2.9.28
verified: true
boot_attempts: 0
status: standby

Immutable OS Model

Overlay Upper (Apps partition, persistent) Read-Write
OverlayFS Merge — unified root filesystem
SquashFS Lower (System partition, immutable) Read-Only

User-installed packages and config changes write to the overlay upper on the Apps partition. The base system image is never modified. Safe mode boots with a tmpfs overlay, bypassing all user modifications. Factory reset wipes the overlay, restoring pristine state.