Network Interface Subnet Allocation Tool

Overview

This tool scans network interfaces, identifies groups connected to the same physical network, detects existing DHCP servers, and calculates available subnets. The outputs are designed to be line-oriented for easy integration with shell scripts and automation.

Features

• Scans network interfaces and identifies groups sharing the same Layer 2 network.
• Detects pre-existing DHCP servers and their offered subnets.
• Calculates available subnets based on user-provided pools and existing allocations.
• Outputs data in a simple, parseable line-oriented format.

Dependencies

Install required system packages (Void Linux) and install define-networks to the system path:

sudo bash install.sh

Usage

Run the tool with appropriate arguments:

define-networks -i eth -t 10 -s 10.0.0.0/8 -m eth0 192.168.1.0/24 -d 24

Arguments:

• -i, --interfaces: Specify interface types (e.g., eth, wlan, tap).
• -t, --timeout: Set the timeout for ARP scanning (in seconds).
• -s, --subnets: Define subnet pools in CIDR format (e.g., 10.0.0.0/8).
• -m, --manual: Assign manual interface-subnet pairs (e.g., eth0 192.168.1.0/24).
• -d, --subnetsize: Set the default subnet size for dynamic allocations (e.g., /25).
• -j, --join: Specify interfaces assumed to share the same Layer 2 network.

Example Command:

define-networks -i eth wlan -t 5 -s 192.168.0.0/16 -m eth0 192.168.1.0/24 -d 24 -j eth0 eth1

Example Output:

The output is line-oriented and looks like this:

ifaces: eth0 eth1 status: discovered subnet: 192.168.1.0/24
ifaces: eth2 status: none subnet: 10.0.0.0/24

Notes

• Permissions: Root or sudo access is required to interact with network interfaces and run ARP scans.
• Output-Only: This tool does not configure DHCP servers or modify network settings. It outputs discovery and allocation data for manual or automated use.
• Line-Oriented Output: Designed for easy parsing in shell scripts and automation workflows.