DHCP Server Scanner

A lightweight cross-platform command-line utility that scans your local network for DHCP servers. It broadcasts DHCP Discover packets, captures server responses, and displays configuration details returned by any responding servers.

Features

• Lightweight, pure C with minimal external dependencies
• Cross-platform support for Linux and macOS
• Uses raw sockets (Linux) and BPF (macOS) for packet capture
• Detects server MAC addresses, IP assignments, DNS, gateway, and subnet info
• Fast network scanning with configurable timeout
• Single binary with no runtime dependencies

Installation

git clone https://github.com/fycth/DHCP-server-scanner.git
cd DHCP-server-scanner
make

Usage

sudo ./bin/dhcpd-detector-release -i <interface> [-t <timeout>]

Parameters:

• -i - Network interface (required)
• -t - Scan timeout in seconds (default: 3)
• -h - Show help
• --version - Show version

Example:

sudo ./bin/dhcpd-detector-release -i eth0 -t 5

Use Cases

• Network diagnostics - Troubleshoot DHCP-related connectivity issues
• Security audits - Detect unauthorized/rogue DHCP servers that could redirect traffic
• IT infrastructure monitoring - Verify expected DHCP servers are responding
• Learning - Understand DHCP protocol mechanics hands-on

Requirements

• Linux or macOS
• GCC or Clang compiler
• Make
• Root/sudo access (required for raw packet operations)

Tech Stack

• C - Core implementation
• Raw sockets - Packet capture on Linux (PF_PACKET)
• BPF - Packet capture on macOS
• Make - Build system