Rust DHCP Server

A simple DHCP server written in Rust that leverages dnsmasq for managing DHCP leases and network configurations. This project allows you to configure multiple network interfaces, set DHCP ranges, and assign static IP addresses based on MAC addresses.

Table of Contents

• Features
• Prerequisites
• Installation
• Configuration
• Usage
• Testing
• Project Structure

Features

• Configurable Network Interfaces: Manage multiple network interfaces with customizable DHCP ranges.
• Static DHCP Leases: Assign fixed IP addresses to devices based on their MAC addresses.
• Automated dnsmasq Setup: Automatically installs and configures dnsmasq based on your configuration.
• Flexible Configuration: Easy-to-edit Config.toml for setting up your DHCP server parameters.

Prerequisites

• Operating System: Debian-based Linux distribution (e.g., Ubuntu, Raspberry Pi OS)
• Rust: Installed with cargo (Installation Guide)
• Root Privileges: Required for installing packages and configuring network interfaces

Installation

1. Clone the Repository

   git clone https://github.com/BetelGeuseee/dhcp-dnsmasq.git

2. Install Dependencies

   The project relies on toml and serde crates, which are specified in the Cargo.toml and will be automatically installed when you build the project.

3. Build the Project

   cargo build --release

   The compiled binary will be located at ./target/release/dhcp-server.

Configuration

The DHCP server is configured using the Config.toml file. Below is an example configuration:

Config.toml

[dhcp_config]
conf = "/etc/dnsmasq.conf"
port = 0 # disable dns in dnsmasq

# ==========================
# dnsmasq Configuration File
# ==========================

# Define the network interfaces to be managed by dnsmasq
[[interfaces]]
# Name of the network interface (e.g., eth0)
name = "raspberry"

# Whether to bind dnsmasq explicitly to the interface
bind_interfaces = true

# DHCP range in the format: start_ip, end_ip, lease_time
dhcp_range = "192.168.50.50,192.168.50.150,12h"

# List of static DHCP leases based on MAC addresses
[[interfaces.static_leases]]
# MAC address of the device
mac = "92:01:c8:a9:b2:c0"

# Reserved IP address for the device
ip = "192.168.50.100"

# Uncomment and configure additional static leases as needed
# [[interfaces.static_leases]]
# mac = "11:22:33:44:55:66"
# ip = "192.168.50.101"

# ==========================
# Additional Interfaces (Optional)
# ==========================
# To manage multiple interfaces, replicate the [[interfaces]] table.

# [[interfaces]]
# name = "eth1"
# bind_interfaces = true
# dhcp_range = "192.168.51.10,192.168.51.100,12h"

# [[interfaces.static_leases]]
# mac = "CC:DD:EE:FF:00:11"
# ip = "192.168.51.50"

Configuration Options:

• [dhcp_config]

  • conf: Path to the dnsmasq configuration file.
  • port: Port number for dnsmasq DNS service (0 to disable DNS).

• [[interfaces]]

  • name: Name of the network interface (e.g., eth0, raspberry).

  • bind_interfaces: Boolean to explicitly bind dnsmasq to the interface.

  • dhcp_range: DHCP IP range in the format start_ip, end_ip, lease_time.

  • [[interfaces.static_leases]]

    • mac: MAC address of the device.
    • ip: Reserved IP address for the device.

Usage

1. Configure the DHCP Server

   Edit the Config.toml file to match your network setup and desired DHCP configurations.

2. Run the DHCP Server

   sudo ./target/release/dhcp-server

   This will:

   • Install dnsmasq if it's not already installed.
   • Generate the dnsmasq configuration file based on Config.toml.
   • Override the existing dnsmasq configuration with the generated one.

3. Restart dnsmasq

   After running the DHCP server, restart dnsmasq to apply the new configurations:

   sudo systemctl restart dnsmasq

Testing

To test the DHCP server setup, follow these steps to create virtual network interfaces and simulate DHCP requests.

1. Create a Virtual Ethernet (veth) Pair

   Name the ends of the veth pair as raspberry (to represent the Raspberry Pi interface) and mindray (to represent the Mindray monitor interface):

   sudo ip link add raspberry type veth peer name mindray

2. Verify the Interfaces

   ip link show

   You should see both raspberry and mindray interfaces listed.

3. Assign ip addresses to both interfaces

   sudo ip addr add 192.168.50.1/24 dev mindray
   sudo ip addr add 192.169.50.2/24 dev raspberry

4. Use the MAC Address from the mindray Interface and Map it to IP in Rust Config

   • Retrieve the MAC address of the mindray interface:

     ip link show mindray

     Example output:

     5: mindray: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
         link/ether aa:bb:cc:dd:ee:ff brd ff:ff:ff:ff:ff:ff
     

     Note the MAC address (aa:bb:cc:dd:ee:ff in this example).

   • Update your Config.toml to map this MAC address to a desired IP:

     [[interfaces.static_leases]]
     mac = "aa:bb:cc:dd:ee:ff"
     ip = "192.168.50.101"

5. Bring Up the Interfaces

   sudo ip link set mindray up
   sudo ip link set raspberry up

6. Install DHCP Client

   sudo apt-get install isc-dhcp-client

7. Send DHCP Request from mindray Interface

   sudo dhclient mindray

   This will send a DHCP request from the mindray interface and should receive an IP address based on your Config.toml settings.

8. Verify the IP Address Assignment

   ip addr show mindray

   Ensure that mindray has been assigned the correct IP address as per your static lease configuration (e.g., 192.168.50.101).

9. Clean Up the veth Pair

After testing, delete the mindray interface. Both ends of the veth pair (raspberry and mindray) will be removed:

```bash
sudo ip link delete mindray
```

Project Structure

dhcp-server/
├── Cargo.toml
├── Config.toml
├── README.md
└── src
    ├── config.rs
    └── main.rs

• Cargo.toml: Rust project configuration, including dependencies.
• Config.toml: Configuration file for the DHCP server.
• src/main.rs: Main application logic for setting up and configuring dnsmasq.
• src/config.rs: Configuration structures for parsing Config.toml.

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