Initial commit: DHCP whitelist service for direct link connections

Features:
- Docker-based DHCP server with MAC address whitelisting
- Binds to specific ethernet interface only
- NO DNS/gateway advertised (direct link only, not a router)
- Configurable network parameters (subnet, DHCP range, lease times)
- Systemd service integration for Arch/Manjaro
- Test environment with isolated network (172.20.0.0/24)
- Auto-configuration script to detect network settings
- Complete Makefile with management targets

Security:
- Only responds to whitelisted MAC addresses
- deny unknown-clients configuration
- Runs in Docker container for isolation

Configuration:
- Copy .example files to create your config
- interface.conf: Network interface to bind to
- whitelist.conf: Allowed MAC addresses
- network.conf: Network parameters (optional)

README.md

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+# DHCP Direct Link Only Service
+
+A Docker-based DHCP server that only serves IP addresses to whitelisted MAC addresses on a specific ethernet interface. Designed for secure, controlled network environments where only authorized devices should receive DHCP leases.
+
+## Features
+
+- **MAC Address Whitelisting**: Only responds to DHCP requests from pre-authorized MAC addresses
+- **Interface Binding**: Binds to a specific ethernet interface only
+- **Docker-Based**: Runs in an isolated container environment
+- **Systemd Integration**: Can be installed as a system service on Arch/Manjaro
+- **Auto-Configuration**: Automatically detects network settings and connected devices
+- **Testing Environment**: Includes isolated test environment with virtual networks
+
+## Requirements
+
+- Docker
+- Docker Compose
+- Make
+- systemd (for service installation)
+- sudo (for service installation)
+
+## Quick Start
+
+1. Auto-configure for current network:
+```bash
+make autoconfig
+```
+
+2. Start the DHCP server:
+```bash
+make up
+```
+
+3. Stop the server:
+```bash
+make down
+```
+
+## Configuration
+
+### Manual Configuration
+
+Edit the following files in the `config/` directory:
+
+- `interface.conf`: Specify the ethernet interface to bind to
+- `whitelist.conf`: List MAC addresses (one per line) that should be served
+
+### Auto Configuration
+
+Run `make autoconfig` to automatically:
+- Detect your ethernet interface
+- Find connected devices on the network
+- Generate configuration files
+
+## Make Targets
+
+| Target | Description | Requires sudo |
+|--------|-------------|---------------|
+| `up` | Start DHCP server in userland mode | No |
+| `down` | Stop DHCP server | No |
+| `install` | Install as systemd service | Yes |
+| `service_up` | Enable and start systemd service | No |
+| `service_down` | Disable and stop systemd service | No |
+| `test` | Run isolated test environment | No |
+| `autoconfig` | Auto-generate configuration | No |
+| `clean` | Remove generated files | No |
+
+## Installation as System Service
+
+To install and run as a systemd service:
+
+```bash
+# Install the service (requires sudo)
+sudo make install
+
+# Start the service
+make service_up
+
+# Check service status
+systemctl status dhcp-whitelist
+
+# Stop the service
+make service_down
+```
+
+The service configuration will be stored in `/etc/dhcp-whitelist/` and will persist across system reboots.
+
+## Testing
+
+Run the test environment with virtual networks:
+
+```bash
+make test
+```
+
+This creates an isolated Docker network with:
+- A DHCP server with test whitelist
+- Test clients with different MAC addresses
+- Validation of whitelist enforcement
+
+## Network Configuration
+
+Default DHCP settings:
+- Subnet: 192.168.75.0/24
+- Range: 192.168.75.10 - 192.168.75.100
+- Gateway: 192.168.75.1
+- DNS: 8.8.8.8, 8.8.4.4
+- Lease time: 12 hours
+
+## Troubleshooting
+
+### DHCP server not responding
+- Check that the interface in `config/interface.conf` is correct
+- Verify the MAC address is in `config/whitelist.conf`
+- Check Docker logs: `docker-compose logs dhcp-server`
+
+### Permission denied errors
+- Service installation requires sudo: `sudo make install`
+- Ensure Docker daemon is running
+- Check that your user is in the docker group
+
+### Service won't start
+- Check systemd logs: `journalctl -u dhcp-whitelist -f`
+- Verify Docker and docker-compose are installed
+- Check configuration files in `/etc/dhcp-whitelist/`
+
+## Security Considerations
+
+- This server uses MAC address filtering as the primary security mechanism
+- MAC addresses can be spoofed; use additional security measures in production
+- The server runs with host networking to access the physical interface
+- Consider firewall rules to restrict DHCP traffic further
+
+## License
+
+MIT