#cloud-config

# Secure VPN Server Cloud-Init Configuration
# 
# BEFORE DEPLOYMENT:
# 1. Replace the example SSH keys below with your actual public keys
# 2. Generate your SSH key: ssh-keygen -t ed25519 -C "your_email@example.com"
# 3. Copy your public key: cat ~/.ssh/id_ed25519.pub
# 4. Paste it in the ssh_authorized_keys sections below
#
# AFTER DEPLOYMENT:
# - Connect via SSH: ssh -p 2222 vpnuser@YOUR_SERVER_IP
# - Download VPN configs: scp -P 2222 -r vpnuser@YOUR_SERVER_IP:/var/lib/vpn/clients/ ./

# SSH Keys Configuration - Add your SSH public keys here
# Keys are defined in the users section below for the vpnuser account

package_update: true
package_upgrade: true

# User configuration
users:
  - name: vpnuser
    shell: /bin/bash
    sudo: ['ALL=(ALL) NOPASSWD:ALL']
    ssh_authorized_keys:
      # Replace these example keys with your actual SSH public keys:
      - "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEXAMPLE1234567890abcdefghijklmnopqrstuvwxyz user@example.com"
      - "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAACAQEXAMPLE1234567890abcdefghijklmnopqrstuvwxyz user2@example.com"

packages:
  - wireguard
  - openvpn
  - easy-rsa
  - stunnel4
  - iptables-persistent
  - curl
  - fail2ban
  - unattended-upgrades

write_files:
  # Enable IP forwarding
  - path: /etc/sysctl.d/99-ip-forward.conf
    content: |
      net.ipv4.ip_forward=1
      net.ipv6.conf.all.forwarding=1
      # Security hardening
      net.ipv4.conf.all.send_redirects=0
      net.ipv4.conf.default.send_redirects=0
      net.ipv4.conf.all.accept_redirects=0
      net.ipv4.conf.default.accept_redirects=0
      net.ipv4.conf.all.secure_redirects=0
      net.ipv4.conf.default.secure_redirects=0
    permissions: '0644'

  # Secure firewall rules with DROP default policy
  - path: /etc/iptables/rules.v4
    content: |
      *filter
      :INPUT DROP [0:0]
      :FORWARD DROP [0:0]
      :OUTPUT ACCEPT [0:0]
      
      # Allow loopback
      -A INPUT -i lo -j ACCEPT
      -A OUTPUT -o lo -j ACCEPT
      
      # Allow established and related connections
      -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
      -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
      
      # Rate limiting for SSH (hardened port)
      -A INPUT -p tcp --dport 2222 -m conntrack --ctstate NEW -m recent --set --name ssh
      -A INPUT -p tcp --dport 2222 -m conntrack --ctstate NEW -m recent --update --seconds 60 --hitcount 4 --name ssh -j DROP
      -A INPUT -p tcp --dport 2222 -j ACCEPT
      
      # Rate limiting for VPN ports
      -A INPUT -p udp --dport 51820 -m conntrack --ctstate NEW -m limit --limit 10/min --limit-burst 20 -j ACCEPT
      -A INPUT -p tcp --dport 1194 -m conntrack --ctstate NEW -m limit --limit 10/min --limit-burst 20 -j ACCEPT  
      -A INPUT -p tcp --dport 443 -m conntrack --ctstate NEW -m limit --limit 20/min --limit-burst 50 -j ACCEPT
      
      # VPN traffic forwarding with security
      -A FORWARD -i wg0 -o eth0 -j ACCEPT
      -A FORWARD -i tun0 -o eth0 -j ACCEPT
      -A FORWARD -i eth0 -o wg0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
      -A FORWARD -i eth0 -o tun0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
      
      # Drop invalid packets
      -A INPUT -m conntrack --ctstate INVALID -j DROP
      -A FORWARD -m conntrack --ctstate INVALID -j DROP

      COMMIT
      
      *nat
      :PREROUTING ACCEPT [0:0]
      :INPUT ACCEPT [0:0]  
      :OUTPUT ACCEPT [0:0]
      :POSTROUTING ACCEPT [0:0]
      
      # NAT rules for VPN traffic
      -A POSTROUTING -s 10.66.66.0/24 ! -d 10.66.66.0/24 -o eth0 -j MASQUERADE
      -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -o eth0 -j MASQUERADE
      
      COMMIT
    permissions: '0644'

  # Fail2ban configuration for VPN protection  
  - path: /etc/fail2ban/jail.d/vpn.conf
    content: |
      [sshd]
      enabled = true
      port = 2222
      filter = sshd
      logpath = /var/log/auth.log
      maxretry = 3
      bantime = 3600
      
      [openvpn]
      enabled = true
      port = 1194,443
      filter = openvpn
      logpath = /var/log/openvpn/server.log
      maxretry = 5
      bantime = 1800
    permissions: '0644'

  # Secure stunnel config template
  - path: /etc/stunnel/stunnel.conf.template
    content: |
      pid = /var/run/stunnel4/stunnel.pid
      setuid = stunnel4
      setgid = stunnel4
      foreground = no
      debug = 3
      output = /var/log/stunnel4/stunnel.log
      
      # Security options
      options = NO_SSLv2
      options = NO_SSLv3
      options = CIPHER_SERVER_PREFERENCE
      ciphersuites = TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
      
      [openvpn-ssl]
      accept = 443
      connect = 127.0.0.1:1194
      cert = /etc/stunnel/stunnel.pem
      # Require client certificates for mutual TLS
      verify = 2
      CAfile = /etc/stunnel/ca.pem
    permissions: '0644'

  # Automatic security updates
  - path: /etc/apt/apt.conf.d/20auto-upgrades
    content: |
      APT::Periodic::Update-Package-Lists "1";
      APT::Periodic::Unattended-Upgrade "1";
    permissions: '0644'

  # SSH hardening configuration
  - path: /etc/ssh/sshd_config.d/99-hardening.conf
    content: |
      # Change default port (update firewall rules accordingly)
      Port 2222
      
      # Protocol and encryption
      Protocol 2
      
      # Authentication
      PermitRootLogin no
      PasswordAuthentication no
      ChallengeResponseAuthentication no
      PubkeyAuthentication yes
      AuthenticationMethods publickey
      
      # Login restrictions
      MaxAuthTries 3
      MaxSessions 2
      LoginGraceTime 30
      
      # Disable unused authentication methods
      KerberosAuthentication no
      GSSAPIAuthentication no
      UsePAM yes
      
      # Network settings
      ClientAliveInterval 300
      ClientAliveCountMax 2
      TCPKeepAlive no
      
      # Disable dangerous features
      AllowAgentForwarding no
      AllowTcpForwarding no
      X11Forwarding no
      PermitTunnel no
      GatewayPorts no
      PermitUserEnvironment no
      
      # Logging
      LogLevel VERBOSE
      SyslogFacility AUTH
      
      # Restrict users (adjust as needed)
      AllowUsers vpnuser
      DenyUsers root
      
      # Crypto settings
      Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
      MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha2-512
      KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512
      
      # Host key algorithms
      HostKeyAlgorithms ssh-ed25519,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,rsa-sha2-256,rsa-sha2-512
    permissions: '0644'

runcmd:
  # Apply sysctl settings
  - sysctl -p /etc/sysctl.d/99-ip-forward.conf
  
  # Auto-detect primary network interface
  - |
    PRIMARY_IFACE=$(ip route | awk '/default/ { print $5 ; exit }')
    sed -i "s/eth0/$PRIMARY_IFACE/g" /etc/iptables/rules.v4
  
  # Load iptables rules
  - iptables-restore < /etc/iptables/rules.v4
  - systemctl enable netfilter-persistent

  # Create VPN directories (user is created automatically by cloud-init)
  - mkdir -p /var/lib/vpn/clients /var/lib/vpn/server
  - chmod 700 /var/lib/vpn /var/lib/vpn/clients /var/lib/vpn/server
  - chown -R vpnuser:vpnuser /var/lib/vpn

  # === WireGuard setup ===
  - mkdir -p /etc/wireguard
  - chmod 700 /etc/wireguard
  
  # Generate WireGuard keys with better entropy
  - |
    umask 077
    wg genkey > /etc/wireguard/server.key
    wg pubkey < /etc/wireguard/server.key > /etc/wireguard/server.pub
    wg genkey > /var/lib/vpn/clients/wg-client.key  
    wg pubkey < /var/lib/vpn/clients/wg-client.key > /var/lib/vpn/clients/wg-client.pub
    chown vpnuser:vpnuser /var/lib/vpn/clients/wg-client.*

  # Create WireGuard server config
  - |
    SERVER_KEY=$(cat /etc/wireguard/server.key)
    CLIENT_PUB=$(cat /var/lib/vpn/clients/wg-client.pub)
    cat > /etc/wireguard/wg0.conf <> vars < /var/lib/vpn/client_name.txt
  
  - openvpn --genkey secret /etc/openvpn/ta.key
  - chmod 600 /etc/openvpn/ta.key /etc/openvpn/easy-rsa/pki/private/*

  # Secure OpenVPN server config
  - |
    mkdir -p /var/log/openvpn
    cat > /etc/openvpn/server.conf <<'EOF'
    port 1194
    proto tcp
    dev tun
    ca /etc/openvpn/easy-rsa/pki/ca.crt
    cert /etc/openvpn/easy-rsa/pki/issued/server.crt
    key /etc/openvpn/easy-rsa/pki/private/server.key
    dh /etc/openvpn/easy-rsa/pki/dh.pem
    
    # Strong crypto
    auth SHA512
    cipher AES-256-GCM
    ncp-ciphers AES-256-GCM:AES-128-GCM
    tls-version-min 1.2
    tls-auth /etc/openvpn/ta.key 0
    
    topology subnet
    server 10.8.0.0 255.255.255.0
    
    # Security options
    remote-cert-tls client
    tls-server
    
    # Networking
    push "redirect-gateway def1 bypass-dhcp"
    push "dhcp-option DNS 9.9.9.9"
    push "dhcp-option DNS 149.112.112.112"
    
    keepalive 10 120
    persist-key  
    persist-tun
    
    # Privileges
    user nobody
    group nogroup
    
    # Logging
    status /var/log/openvpn/status.log
    log-append /var/log/openvpn/server.log
    verb 3
    mute 20
    
    explicit-exit-notify 1
    EOF

  - systemctl enable openvpn@server
  - systemctl start openvpn@server

  # === Secure stunnel setup ===
  - |
    # Get public IP with fallback
    PUBLIC_IP=$(curl -s --max-time 10 ifconfig.me || curl -s --max-time 10 icanhazip.com || hostname -I | awk '{print $1}')
    
    # Generate stunnel server certificate using OpenVPN CA (not self-signed)
    cd /etc/openvpn/easy-rsa
    STUNNEL_SERVER="stunnel-server-$(openssl rand -hex 4)"
    ./easyrsa gen-req $STUNNEL_SERVER nopass
    ./easyrsa sign-req server $STUNNEL_SERVER
    
    # Create stunnel certificate bundle (cert + key)
    cat /etc/openvpn/easy-rsa/pki/issued/$STUNNEL_SERVER.crt \
        /etc/openvpn/easy-rsa/pki/private/$STUNNEL_SERVER.key > /etc/stunnel/stunnel.pem
    chmod 600 /etc/stunnel/stunnel.pem
    
    # Copy CA for client verification (same CA as OpenVPN)
    cp /etc/openvpn/easy-rsa/pki/ca.crt /etc/stunnel/ca.pem
    
    # Generate client certificate for stunnel mutual TLS
    STUNNEL_CLIENT="stunnel-client-$(openssl rand -hex 4)"
    ./easyrsa gen-req $STUNNEL_CLIENT nopass
    ./easyrsa sign-req client $STUNNEL_CLIENT
    
    # Create client certificate bundle for stunnel
    cat /etc/openvpn/easy-rsa/pki/issued/$STUNNEL_CLIENT.crt \
        /etc/openvpn/easy-rsa/pki/private/$STUNNEL_CLIENT.key > /var/lib/vpn/clients/client.pem
    chmod 600 /var/lib/vpn/clients/client.pem
    
    # Use secure stunnel config
    cp /etc/stunnel/stunnel.conf.template /etc/stunnel/stunnel.conf

  # Start services with proper ordering
  - systemctl enable stunnel4 fail2ban
  - sleep 5  # Allow OpenVPN to fully start
  - systemctl start stunnel4 
  - systemctl start fail2ban

  # Generate client configurations securely  
  - |
    PUBLIC_IP=$(curl -s --max-time 10 ifconfig.me || curl -s --max-time 10 icanhazip.com || hostname -I | awk '{print $1}')
    CLIENT_NAME=$(cat /var/lib/vpn/client_name.txt)
    
    # WireGuard client config
    CLIENT_KEY=$(cat /var/lib/vpn/clients/wg-client.key)
    SERVER_PUB=$(cat /etc/wireguard/server.pub)
    cat > /var/lib/vpn/clients/wg-client.conf < /var/lib/vpn/clients/client-direct.ovpn <
    $(cat /etc/openvpn/easy-rsa/pki/ca.crt)
    
    
    $(sed -n '/BEGIN CERTIFICATE/,/END CERTIFICATE/p' /etc/openvpn/easy-rsa/pki/issued/$CLIENT_NAME.crt)
    
    
    $(cat /etc/openvpn/easy-rsa/pki/private/$CLIENT_NAME.key)
    
    
    $(cat /etc/openvpn/ta.key)
    
    EOF
    
    # Secure stunnel client config
    cat > /var/lib/vpn/clients/stunnel-client.conf < /var/lib/vpn/clients/SECURITY-README.md </dev/null || true
    chmod 640 /var/log/stunnel4/* 2>/dev/null || true
    
    # Remove unnecessary packages
    apt autoremove -y
    
    # Update package database
    apt update

  # Status check
  - sleep 15
  - systemctl status wg-quick@wg0 openvpn@server stunnel4 fail2ban --no-pager