# Alpine Linux USB Rescue ISO

A bootable hybrid ISO that:

- Gets an IP via **DHCP on `eth0`**
- Automatically opens a **Nebula overlay tunnel**
- Runs **OpenSSH** (login: `root` / `alpine`)
- Carries all tools needed to **install Alpine onto the host machine** (`setup-alpine`, `setup-disk`, `parted`, …)

The ISO is a hybrid image — it can be written to a USB stick with `dd` *or* burned to a CD/DVD.

---

## Prerequisites

- Docker + Docker Compose
- A Nebula certificate set for this node (see below)

---

## 1. Place Nebula certificates

Put the following files in `nebula/`:

```
nebula/
  nebula       ← binary (already included)
  config.yml   ← already included, edit as needed
  ca.crt       ← your Nebula CA certificate  ← YOU PROVIDE
  host.crt     ← this node's certificate     ← YOU PROVIDE
  host.key     ← this node's private key     ← YOU PROVIDE
```

`ca.crt`, `host.crt`, and `host.key` are gitignored.

---

## 2. Build the ISO

```bash
docker compose run --rm alpine bash /scripts/create.sh
```

The ISO is written to `output/rescue-alpine.iso`.

---

## 3. Write to USB

```bash
dd if=output/rescue-alpine.iso of=/dev/sdX bs=4M status=progress && sync
```

Replace `/dev/sdX` with your USB device (check with `lsblk`). **All data on the device will be erased.**

Or burn to CD/DVD:

```bash
cdrecord dev=/dev/sr0 output/rescue-alpine.iso
```

---

## 4. Boot and connect

1. Insert USB and boot the target machine from it.
2. The system comes up fully in RAM — no writes to the host disk.
3. On boot, `eth0` gets an IP via DHCP, then the Nebula tunnel comes up automatically.
4. SSH in via the Nebula overlay IP (see `nebula/config.yml`):

```bash
ssh root@<nebula-ip>
# password: alpine
```

---

## 5. Install Alpine onto the host machine

Once SSH'd in (or at the local console):

```bash
# Interactive guided installer — partitions disk, installs Alpine
setup-alpine

# Or use setup-disk for more control
setup-disk -m sys /dev/sda
```

All required tools (`parted`, `e2fsprogs`, `dosfstools`, `btrfs-progs`, `alpine-conf`, …) are pre-installed.

---

## Default credentials

| Field    | Value    |
|----------|----------|
| Username | `root`   |
| Password | `alpine` |

Change this in `scripts/chroot-setup.sh` before building if needed.

---

## Architecture

```
ISO (hybrid — bootable on USB or CD)
└── isolinux (BIOS boot)
    ├── vmlinuz-lts
    └── initramfs.gz   ← entire Alpine system packed as cpio+gzip
        ├── eth0 DHCP  (openrc networking)
        ├── nebula      → /usr/local/bin/nebula
        ├── /etc/nebula/ (config + certs)
        ├── OpenSSH (sshd)
        └── Alpine install tools
```

The system runs **entirely in RAM** — the host disk is never touched until you explicitly run the installer.