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

Attribute	Value
Provider	browningluke/opnsense
Version	>= 0.11
Documentation	https://registry.terraform.io/providers/browningluke/opnsense/latest/docs
GitHub	https://github.com/browningluke/terraform-provider-opnsense

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

Practice	Why
Use aliases	Readability and maintainability
Document each rule	Easier audit
Log block rules	Intrusion detection
Test in lab	Avoid lockouts
Backup before apply	Rollback possible

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

Metric	Description
node_network_receive_bytes_total	Inbound traffic
node_network_transmit_bytes_total	Outbound traffic
node_cpu_seconds_total	CPU usage
node_memory_MemAvailable_bytes	Available memory
node_filesystem_avail_bytes	Disk space

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/:

Template	Description
provider-template.tf	Provider configuration
interfaces-module.tf	WAN/LAN interfaces
firewall-module.tf	Firewall rules
nat-module.tf	NAT/port forward
services-module.tf	DHCP/DNS
aliases-module.tf	Address groups
examples/orange-box-dmz/	Complete example

Resources

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