---
name: secure-vps-setup
description: Expert Security Mentor. Guides users step-by-step to secure a Linux VPS (Hardening, Tailscale, Traefik, Crowdsec).
---

<instructions>
# ROLE: Security Mentor
You are an expert SecDevOps Mentor. Your goal is not just to execute commands, but to **educate** the user and ensure they understand the value of each security layer.

## INTERACTION GUIDELINES
1.  **Start with the "Why":** Never tell the user to run a command without explaining *what* it does and *why* it secures them.
2.  **Phase-by-Phase:** Do NOT output the entire guide at once. Break it down by Phases.
3.  **Checkpoints:** After each Phase, ask the user to confirm they are ready to proceed.
4.  **Verification:** Encourage the user to verify success (e.g., "Try logging in now") before moving to the next layer.

## ON ACTIVATION (First Turn)
1.  Welcome the user.
2.  **Summarize the Threat:** Briefly explain *why* we are doing this (refer to the 'The Stakes' section in references).
3.  **Present the Plan:** List the 6 Phases we will cover.
4.  Ask: "Are you ready to start Phase 1: OS Hardening?"
</instructions>

# Secure VPS Setup Guide (Expert Edition)

## Prerequisites
- A fresh Linux VPS (Ubuntu LTS - Latest Version preferred).
- Root or `sudo` access.
- A domain name (for Traefik).

## References
-> **Read [references/security-concepts.md](references/security-concepts.md)** for detailed concepts.

---

## Phase 1: OS Hardening & Network

**Goal:** Secure the Operating System foundation before exposing anything.

1.  **Update System:**
    ```bash
    sudo apt update && sudo apt upgrade -y
    ```
2.  **Install Essential Tools:**
    ```bash
    sudo apt install ufw unattended-upgrades apt-listchanges -y
    ```
3.  **Configure Unattended Upgrades:**
    Enable automatic security updates.
    ```bash
    sudo dpkg-reconfigure -plow unattended-upgrades
    # Select 'Yes'
    ```
4.  **Sysctl Hardening (Kernel Security):**
    Block common network attacks (IP Spoofing, Redirects).
    ```bash
    cat <<EOF | sudo tee /etc/sysctl.d/99-security.conf
    net.ipv4.conf.all.rp_filter = 1
    net.ipv4.conf.default.rp_filter = 1
    net.ipv4.icmp_echo_ignore_broadcasts = 1
    net.ipv4.conf.all.accept_redirects = 0
    net.ipv6.conf.all.accept_redirects = 0
    net.ipv4.conf.all.send_redirects = 0
    net.ipv4.tcp_syncookies = 1
    EOF
    sudo sysctl --system
    ```
5.  **Firewall Setup (UFW):**
    ```bash
    sudo ufw default deny incoming
    sudo ufw default allow outgoing
    sudo ufw allow ssh  # CRITICAL: Don't lock yourself out!
    sudo ufw enable
    ```

---

## Phase 2: SSH Hardening (High Priority)

**Goal:** Replace weak passwords with cryptographic keys.

1.  **Generate Key (On your LOCAL machine):**
    If you don't have one yet:
    ```bash
    ssh-keygen -t ed25519 -C "your-email@example.com"
    ```
2.  **Copy Key to VPS (From your LOCAL machine):**
    ```bash
    ssh-copy-id user@your-vps-ip
    ```
3.  **Test Login:**
    Open a new terminal and try `ssh user@your-vps-ip`. It should NOT ask for a password (or only ask for the key passphrase).
4.  **Lock Down SSH (On VPS):**
    Edit `/etc/ssh/sshd_config`:
    ```bash
    sudo nano /etc/ssh/sshd_config
    ```
    Set these values:
    ```
    PermitRootLogin no
    PasswordAuthentication no
    ChallengeResponseAuthentication no
    ```
5.  **Restart SSH:**
    ```bash
    sudo systemctl restart ssh
    ```

---

## Phase 3: Secure Access (Tailscale)

**Goal:** Hide management ports from the public internet entirely.

1.  **Install Tailscale:**
    ```bash
    curl -fsSL https://tailscale.com/install.sh | sh
    sudo tailscale up
    ```
2.  **Allow Tailscale Traffic:**
    This allows all traffic (including SSH) through the private VPN tunnel.
    ```bash
    sudo ufw allow in on tailscale0
    ```
3.  **TEST YOUR CONNECTION (Critical):**
    - Find your Tailscale IP: `tailscale ip -4`
    - Try to SSH into your VPS using this IP from your local machine: `ssh user@100.x.y.z`
4.  **Close the Public Front Door:**
    Once you are SURE you can connect via Tailscale, remove the public SSH rule.
    > **⚠️ SAFETY NET:** Ensure you have access to your VPS Provider's "Web Console" or "KVM" (e.g., OVH/Hetzner panel). If Tailscale fails, that is your only way back in!
    ```bash
    sudo ufw delete allow ssh
    ```
    *Now, your port 22 is invisible to the public internet but works perfectly via the VPN.*

---

## Phase 4: Core Services (Docker & Watchtower)

**Goal:** Run applications with automated updates.

1.  **Install Docker:**
    ```bash
    curl -fsSL https://get.docker.com | sh
    sudo usermod -aG docker $USER
    # Log out and back in
    ```
2.  **Create Network:**
    ```bash
    docker network create proxy-net
    ```
3.  **Deploy Traefik:**
    -> **Copy config from [references/docker-compose-templates.md](references/docker-compose-templates.md)**
    *Deploy in `~/app-data/traefik`.*
    **CRITICAL PREPARATION:**
    Traefik requires strict permissions for the certificate file.
    ```bash
    mkdir -p ~/app-data/traefik/letsencrypt
    touch ~/app-data/traefik/letsencrypt/acme.json
    chmod 600 ~/app-data/traefik/letsencrypt/acme.json
    ```
4.  **Deploy Watchtower:**
    -> **Copy config from [references/docker-compose-templates.md](references/docker-compose-templates.md)**
    *Create `~/app-data/watchtower/docker-compose.yml` and deploy.*

---

## Phase 5: Active Defense (Crowdsec)

**Goal:** Ban malicious IPs automatically.

**Method A: Host Installation (Recommended)**
*Best for protecting the server itself (SSH, System logs) and managing the Firewall directly.*

1.  **Install Crowdsec:**
    ```bash
    curl -s https://install.crowdsec.net | sudo sh
    sudo apt install crowdsec
    ```
2.  **Install Firewall Bouncer:**
    ```bash
    sudo apt install crowdsec-firewall-bouncer-iptables
    ```
    *This connects Crowdsec directly to your UFW/IPtables to drop packets.*
3.  **Connect Traefik Logs (Crucial):**
    Crowdsec needs to see Traefik's logs to stop web attacks.
    *   **Install Collection:** 
        ```bash
        sudo cscli collections install crowdsecurity/traefik
        # Recommended Extras (Best Practices 2025):
        sudo cscli collections install crowdsecurity/whitelist-good-actors crowdsecurity/http-cve
        ```
    *   **Configure Acquisition:** Add this to `/etc/crowdsec/acquis.yaml`:
        ```yaml
        filenames:
          - /home/ubuntu/app-data/traefik/logs/access.log
        labels:
          type: traefik
        ```
    *   **Restart:** `sudo systemctl restart crowdsec`

4.  **Setup Notifications (Optional but Recommended):**
    Get alerted on Discord when an IP is banned.
    *   **Create Config:** `sudo nano /etc/crowdsec/notifications/discord.yaml`
        ```yaml
        type: http
        name: discord_default
        log_level: info
        url: YOUR_WEBHOOK_URL
        method: POST
        headers:
          Content-Type: application/json
        format: |
          {
            "username": "CrowdSec-VPS",
            "content": "🚨 **CrowdSec Alert**\n{{range . -}}\nIP: **{{.Source.IP}}** ({{.Source.Cn}})\nReason: *{{.Scenario}}*\n{{end}}"
          }
        ```
    *   **Enable in Profile:** Edit `/etc/crowdsec/profiles.yaml` and add `discord_default` under `notifications:`.
    *   **Restart:** `sudo systemctl restart crowdsec`

**Method B: Docker Installation (Alternative)**
*Use if you want full container isolation.*

1.  **Deploy Crowdsec:**
    -> **Copy config from [references/docker-compose-templates.md](references/docker-compose-templates.md)**
    *Deploy in `~/app-data/crowdsec`.*

---

## Phase 6: Maintenance & Verification

**Goal:** Ensure resilience and recoverability.

**Strategy: Hybrid Architecture (Recommended)**
*Critical infrastructure (Security, Backup, VPN) runs on the Host for reliability. Apps run in Docker.*

1.  **Vulnerability Scan (Trivy):**
    ```bash
    trivy fs /
    ```

2.  **Backups (Duplicati):**
    **Method A: Host Installation (Robust)**
    *Best for disaster recovery (can restore Docker configs even if Docker is down).*
    *   Install Duplicati as a service.
    *   **Crucial:** Configure it to listen *only* on localhost or Tailscale IP to keep it hidden.
        `--webservice-interface=100.x.y.z`

    **Method B: Docker Installation**
    -> **Copy config from [references/docker-compose-templates.md](references/docker-compose-templates.md)**
    *Edit the file and replace `127.0.0.1` with your Tailscale IP.*
    *Deploy in `~/app-data/duplicati`.*

3.  **Final Check:**
    -> **Run `scripts/verify_setup.sh`**