Subnetron

Subnetron is a high-performance subnet calculator built in Go.
It validates IP addresses and CIDR notations, generates subnet masks, computes network and broadcast addresses, determines usable IP ranges and calculates host availability — all with comprehensive unit test coverage to ensure correctness and reliability.

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Features

• IP Address Validation – Rejects invalid or reserved addresses.
• CIDR Validation – Supports the full IPv4 range (/0–/32).
• Subnet Mask Generation – Derives masks directly from CIDR values.
• Network Address Calculation – Computes the base network address via bitwise operations.
• Broadcast Address Calculation – Identifies the last address in a subnet.
• Usable IP Range – Determines the first and last usable hosts.
• Host Capacity – Calculates available host addresses per subnet.
• Unit Tested – All core functions validated using Go’s testing framework.

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Installation

Option 1: Download Prebuilt Binary

1. Go to the Releases page.
2. Download the binary for your platform (Linux, macOS, or Windows).
3. Make it executable (Linux/macOS):

   chmod +x subnetron

    Run the tool:

    ./subnetron -ip 192.168.1.10 -cidr 24 

Option 2: Build from Source

Make sure you have Go installed.

    git clone https://github.com/lenardjombo/subnetron.git
    cd subnetron
    go build -o subnetron main.go
    ./subnetron -ip 192.168.1.10 -cidr 24

Why This Project Matters

Subnetting is a foundational skill in networking, system administration and cybersecurity. Misconfigurations in subnetting often lead to:

• Inefficient IP allocation and wasted address space
• Increased routing complexity
• Security vulnerabilities from improper segmentation

Subnetron automates subnet calculations, reducing human error and providing:

• Network Engineers → Faster IP planning and allocation
• Security Analysts → Reliable tools for auditing segmentation
• Students & Learners → A hands-on way to master IP addressing

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How Subnetron Performs Its Calculations

Subnetron leverages CIDR arithmetic and bitwise operations to compute subnet details.

Example: 192.168.1.10/24

• CIDR → Subnet Mask

  • /24 means 24 network bits, 8 host bits
  • Subnet mask → 255.255.255.0

• Network Address

192.168.1.10 AND 255.255.255.0 = 192.168.1.0

• Broadcast Address

Invert mask, OR with network = 192.168.1.255

• Usable Range

• First usable → 192.168.1.1

• Last usable → 192.168.1.254

• Host Capacity

2^(32-24) - 2 = 254 usable hosts

Sample outputs :

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Testing Strategy

Subnetron includes unit tests for every core function, ensuring accuracy and preventing regressions.
Coverage includes:
Sample tests :

• CIDR validation (0 ≤ CIDR ≤ 32)
• IP validation (rejects invalid/reserved addresses)
• Subnet mask generation for multiple CIDR values
• Network & broadcast address derivation
• Usable IP range correctness
• Host count verification

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Technical Highlights

• Written in Go for performance and reliability
• Uses Go’s net and math standard libraries
• Structured with modular, testable functions
• Implements defensive programming practices

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Next Steps

• Extend support for IPv6 subnetting
• Build a CLI tool for system administrators
• Add a web-based UI for educational and visualization purposes

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Project Status

• Completed core functionality
• Comprehensive testing included
• Planned feature expansions (IPv6, CLI, Web UI)

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License

This project is released under the MIT License.

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