Ops Opnsense

OPNsense Configuration (Terraform)

Complete guide to configure OPNsense declaratively with Terraform and the browningluke/opnsense provider.

When to use this Skill

Activate this skill to:

• Configure OPNsense network interfaces (WAN, LAN, VLANs)
• Manage firewall rules
• Configure NAT and port forwarding
• Manage DHCP and DNS services
• Create aliases to simplify rules

Do not use for:

• Initial OPNsense installation (see manual documentation)
• VM provisioning (use /ops:ops-proxmox)
• Advanced OPNsense plugins (HAProxy, Suricata)

Terraform Provider

Provider Configuration

terraform {
  required_providers {
    opnsense = {
      source  = "browningluke/opnsense"
      version = "~> 0.11"
    }
  }
}

provider "opnsense" {
  uri                 = var.opnsense_uri        # https://192.168.10.1
  api_key             = var.opnsense_api_key    # Sensitive
  api_secret          = var.opnsense_api_secret # Sensitive
  allow_insecure = true                    # false in production
}

Configuration Patterns

1. Network Interfaces

# WAN interface (DHCP from ISP box)
resource "opnsense_interface" "wan" {
  device        = "vtnet0"
  description   = "WAN - Orange Box"
  ipv4_type     = "dhcp"
  block_private = true
  block_bogons  = true
}

# LAN interface (static IP)
resource "opnsense_interface" "lan" {
  device      = "vtnet1"
  description = "LAN - Local network"
  ipv4_type   = "static"
  ipv4_addr   = "192.168.10.1"
  ipv4_mask   = 24
}

2. Firewall Rules (CRITICAL: Anti-lockout)

# MANDATORY: Anti-lockout rule (ALWAYS first)
resource "opnsense_firewall_filter" "anti_lockout" {
  interface        = "lan"
  direction        = "in"
  action           = "pass"
  protocol         = "tcp"
  source_net       = "lannet"
  destination_net  = "(self)"
  destination_port = "443"
  description      = "ANTI-LOCKOUT: Admin access"
  sequence         = 1
}

# Allow outbound HTTP/HTTPS
resource "opnsense_firewall_filter" "lan_to_web" {
  interface        = "lan"
  direction        = "in"
  action           = "pass"
  protocol         = "tcp"
  source_net       = "lannet"
  destination_net  = "any"
  destination_port = "80,443"
  description      = "Allow outbound HTTP/HTTPS"
  sequence         = 10
}

# Block everything else (deny by default)
resource "opnsense_firewall_filter" "lan_block_all" {
  interface   = "lan"
  direction   = "in"
  action      = "block"
  protocol    = "any"
  source_net  = "any"
  destination_net = "any"
  log         = true
  description = "Block and log everything else"
  sequence    = 65535
}

3. NAT / Port Forwarding

# Port forward HTTPS to internal web server
resource "opnsense_nat_port_forward" "https_to_web" {
  interface        = "wan"
  protocol         = "tcp"
  source_net       = "any"
  source_port      = "443"
  destination_net  = "wanip"
  destination_port = "443"
  target           = "192.168.10.20"
  local_port       = "443"
  description      = "HTTPS to web server"
  nat_reflection   = "enable"
  filter_rule_association = "add-associated"
}

# SSH on non-standard port
resource "opnsense_nat_port_forward" "ssh_to_server" {
  interface        = "wan"
  protocol         = "tcp"
  source_net       = "any"
  source_port      = "2222"
  destination_net  = "wanip"
  destination_port = "2222"
  target           = "192.168.10.10"
  local_port       = "22"
  description      = "SSH to server (port 2222)"
}

4. DHCP/DNS Services

# DHCP server on LAN
resource "opnsense_dhcp_v4_server" "lan" {
  interface   = "lan"
  enabled     = true
  range_from  = "192.168.10.100"
  range_to    = "192.168.10.200"
  gateway     = "192.168.10.1"
  dns_servers = ["192.168.10.1"]
  domain      = "home.local"
  lease_time  = 86400
}

# DHCP reservation
resource "opnsense_dhcp_v4_static_map" "server_web" {
  interface   = "lan"
  mac         = "00:11:22:33:44:55"
  ipaddr      = "192.168.10.20"
  hostname    = "server-web"
  description = "Main web server"
}

# DNS forwarder
resource "opnsense_unbound_forward" "cloudflare" {
  enabled  = true
  host     = "1.1.1.1"
  port     = 53
  priority = 10
}

# Local DNS entry
resource "opnsense_unbound_host_override" "server_web" {
  enabled  = true
  hostname = "server"
  domain   = "home.local"
  server   = "192.168.10.20"
}

5. Aliases

# Server alias
resource "opnsense_firewall_alias" "servers_web" {
  name        = "SERVERS_WEB"
  type        = "host"
  content     = ["192.168.10.20", "192.168.10.21"]
  description = "Internal web servers"
}

# Port alias
resource "opnsense_firewall_alias" "ports_web" {
  name        = "PORTS_WEB"
  type        = "port"
  content     = ["80", "443", "8080"]
  description = "Web service ports"
}

# Use in a rule
resource "opnsense_firewall_filter" "to_web_servers" {
  interface        = "lan"
  action           = "pass"
  protocol         = "tcp"
  source_net       = "lannet"
  destination_net  = opnsense_firewall_alias.servers_web.name
  destination_port = opnsense_firewall_alias.ports_web.name
  description      = "Access to web servers"
}

Security

Mandatory Rules

1. Anti-lockout (sequence = 1)

   • ALWAYS present
   • Allows admin access from LAN
   • Never delete

2. Deny by default (sequence = 65535)

   • Block anything not explicitly allowed
   • Log to detect attempts

3. Secure credentials

   • Environment variables or terraform.tfvars
   • NEVER in code
   • NEVER committed

Best Practices

ISP Box + OPNsense Architecture

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│   Internet      │     │   Orange Box    │     │    OPNsense     │
│                 │────▶│   (192.168.1.1) │────▶│   WAN: DHCP     │
│                 │     │   DMZ Mode      │     │   LAN: .10.1    │
└─────────────────┘     └─────────────────┘     └────────┬────────┘
                                                         │
                                           ┌─────────────┴─────────────┐
                                           │                           │
                                    ┌──────┴──────┐             ┌──────┴──────┐
                                    │  Server     │             │   Client    │
                                    │  .10.20     │             │   DHCP      │
                                    └─────────────┘             └─────────────┘

Orange Box DMZ Configuration

1. Access the Livebox: http://192.168.1.1
2. Network > NAT/PAT > DMZ
3. Enable DMZ to OPNsense WAN IP
4. All ports are redirected to OPNsense

WireGuard VPN (P3)

WireGuard VPN server configuration:

# WireGuard interface
resource "opnsense_wireguard_server" "vpn" {
  name         = "wg0"
  enabled      = true
  listen_port  = 51820
  tunnel_addr  = "10.10.10.1/24"
  dns          = "192.168.10.1"
  private_key  = var.wireguard_private_key  # Sensitive
}

# Peer (VPN client)
resource "opnsense_wireguard_peer" "laptop" {
  server_id   = opnsense_wireguard_server.vpn.id
  name        = "laptop-chris"
  public_key  = "CLIENT_PUBLIC_KEY"
  allowed_ips = "10.10.10.2/32"
}

# Firewall rule for WireGuard
resource "opnsense_firewall_filter" "wireguard_in" {
  interface        = "wan"
  direction        = "in"
  action           = "pass"
  protocol         = "udp"
  destination_port = "51820"
  description      = "WireGuard VPN"
}

Prometheus Monitoring (P3)

node_exporter Installation

1. Install the node_exporter package via OPNsense
2. System > Services > node_exporter
3. Enable and configure the port (9100)

Prometheus Configuration

# prometheus.yml
scrape_configs:
  - job_name: 'opnsense'
    static_configs:
      - targets: ['192.168.10.1:9100']
    metrics_path: /metrics

Useful Metrics

Troubleshooting

API connection error

# Test the connection
curl -k -u "api-key:api-secret" \
  "https://192.168.10.1/api/core/firmware/status"

# Check:
# 1. API enabled (System > Settings > Administration)
# 2. API user with permissions
# 3. Firewall is not blocking
# 4. HTTPS certificate

Lockout (lost access)

# Via Proxmox/local console
pfctl -d                    # Disable firewall
# Fix via web interface
pfctl -e                    # Re-enable firewall

Terraform state out of sync

# Import existing resource
terraform import opnsense_firewall_filter.rule "uuid"

# Refresh
terraform refresh

# Force recreation
terraform taint opnsense_firewall_filter.rule
terraform apply

Available Templates

Templates are in .claude/templates/opnsense/:

Resources

• OPNsense Documentation
• Terraform Provider
• OPNsense API
• WireGuard OPNsense