OPNsense MCP Server


A Model Context Protocol (MCP) server for comprehensive OPNsense firewall management. This server enables AI assistants like Claude to directly manage firewall configurations, diagnose network issues, and automate complex networking tasks.

Features

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- Complete CRUD operations for firewall rules
- Proper handling of API-created "automation rules"
- Inter-VLAN routing configuration
- Batch rule creation and management
- Enhanced persistence with multiple fallback methods

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- Outbound NAT rule management
- NAT mode control (automatic/hybrid/manual/disabled)
- No-NAT exception rules for inter-VLAN traffic
- Automated DMZ NAT issue resolution
- Direct XML configuration manipulation

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- Comprehensive routing analysis
- ARP table inspection with vendor identification
- Interface configuration management
- Network connectivity troubleshooting
- Auto-fix capabilities for common issues

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- Direct command execution on OPNsense
- Configuration file manipulation
- System-level operations not available via API
- Service management and restarts

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- VLAN management
- DHCP lease viewing and management
- DNS blocklist configuration
- HAProxy load balancer support
- Configuration backup and restore
- Infrastructure as Code support

Installation

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- Node.js 18+ or Bun 1.0+
- OPNsense firewall (v24.7+ recommended)
- API credentials for OPNsense
- SSH access (optional, for advanced features)

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1. Install the package:
``bash
npm install -g opnsense-mcp-server
`

2. Create a .env file with your credentials:
`bash


Required

OPNSENSE_HOST=https://your-opnsense-host:port
OPNSENSE_API_KEY=your-api-key
OPNSENSE_API_SECRET=your-api-secret
OPNSENSE_VERIFY_SSL=false

Optional - for SSH features

OPNSENSE_SSH_HOST=your-opnsense-host
OPNSENSE_SSH_USERNAME=root
OPNSENSE_SSH_PASSWORD=your-password

Or use SSH key

OPNSENSE_SSH_KEY_PATH=~/.ssh/id_rsa

`

3. Start the MCP server:
`bash
opnsense-mcp-server
`

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Bun provides significantly faster startup times and better performance.

1. Install Bun (if not already installed):
`bash
curl -fsSL https://bun.sh/install | bash
`

2. Clone and install:
`bash
git clone https://github.com/vespo92/OPNSenseMCP.git
cd OPNSenseMCP
bun install
`

3. Create your .env file (same as npm version above)

4. Run with Bun:
`bash


Development with hot reload

bun run dev:bun

Production

bun run start:bun
`

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`json
{
"mcpServers": {
"opnsense": {
"command": "bun",
"args": ["run", "/path/to/OPNSenseMCP/src/index.ts"],
"env": {
"OPNSENSE_HOST": "https://your-opnsense:port",
"OPNSENSE_API_KEY": "your-key",
"OPNSENSE_API_SECRET": "your-secret",
"OPNSENSE_VERIFY_SSL": "false"
}
}
}
}
`

Usage with Claude Desktop (npm)

Add to your Claude Desktop configuration (claude_desktop_config.json):

`json
{
"mcpServers": {
"opnsense": {
"command": "npx",
"args": ["opnsense-mcp-server"],
"env": {
"OPNSENSE_HOST": "https://your-opnsense:port",
"OPNSENSE_API_KEY": "your-key",
"OPNSENSE_API_SECRET": "your-secret",
"OPNSENSE_VERIFY_SSL": "false"
}
}
}
}
`

Common Use Cases

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`javascript
// Automatically fix DMZ to LAN routing
await mcp.call('nat_fix_dmz', {
dmzNetwork: '10.0.6.0/24',
lanNetwork: '10.0.0.0/24'
});
`

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`javascript
// Allow NFS from DMZ to NAS
await mcp.call('firewall_create_rule', {
action: 'pass',
interface: 'opt8',
source: '10.0.6.0/24',
destination: '10.0.0.14/32',
protocol: 'tcp',
destination_port: '2049',
description: 'Allow NFS from DMZ'
});
`

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`javascript
// Run comprehensive routing diagnostics
await mcp.call('routing_diagnostics', {
sourceNetwork: '10.0.6.0/24',
destNetwork: '10.0.0.0/24'
});
`

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`javascript
// Run any OPNsense CLI command
await mcp.call('system_execute_command', {
command: 'pfctl -s state | grep 10.0.6'
});
`

MCP Tools Reference

The server provides 50+ MCP tools organized by category:

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- firewall_list_rules - List all firewall rules
- firewall_create_rule - Create a new rule
- firewall_update_rule - Update existing rule
- firewall_delete_rule - Delete a rule
- firewall_apply_changes - Apply pending changes

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- nat_list_outbound - List outbound NAT rules
- nat_set_mode - Set NAT mode
- nat_create_outbound_rule - Create NAT rule
- nat_fix_dmz - Fix DMZ NAT issues
- nat_analyze_config - Analyze NAT configuration

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- arp_list - List ARP table entries
- routing_diagnostics - Diagnose routing issues
- routing_fix_all - Auto-fix routing problems
- interface_list - List network interfaces
- vlan_create - Create VLAN

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- system_execute_command - Execute CLI command
- backup_create - Create configuration backup
- service_restart - Restart a service

For a complete list, see docs/api/mcp-tools.md.

Documentation

- Quick Start Guide
- Configuration Guide
- NAT Management
- SSH/CLI Execution
- Firewall Rules
- Troubleshooting

Testing

The repository includes comprehensive testing utilities:

`bash


Test NAT functionality

npx tsx scripts/test/test-nat-ssh.ts

Test firewall rules

npx tsx scripts/test/test-rules.ts

Test routing diagnostics

npx tsx scripts/test/test-routing.ts

Run all tests

npm test
`

Development

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`bash
git clone https://github.com/vespo92/OPNSenseMCP.git
cd OPNSenseMCP
npm install
npm run build
`

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`
OPNSenseMCP/
├── src/ # Source code
│ ├── api/ # API client
│ ├── resources/ # Resource implementations
│ └── index.ts # MCP server entry
├── docs/ # Documentation
├── scripts/ # Utility scripts
│ ├── test/ # Test scripts
│ ├── debug/ # Debug utilities
│ └── fixes/ # Fix scripts
└── dist/ # Build output
`

Troubleshooting

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- Verify API key and secret are correct
- Ensure API access is enabled in OPNsense
- Check firewall rules allow API access

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- Verify SSH credentials in .env
- Ensure SSH is enabled on OPNsense
- Check user has appropriate privileges

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- NAT management requires SSH access
- Add SSH credentials to environment variables
- Test with: npx tsx scripts/test/test-nat-ssh.ts`

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

- Issues: GitHub Issues
- Discussions: GitHub Discussions
- Documentation: Full Documentation

Acknowledgments

- Built for use with Anthropic's Claude
- Implements the Model Context Protocol
- Designed for OPNsense firewall

---

Version: 0.8.2 | Status: Production Ready | Last Updated: August 2025