Enhanced CIDR Block Calculator with Expanded Input Formats in Go
Jan 07, 2025 pm 12:07 PMEfficient management of IP address ranges is critical in network engineering, cloud infrastructure, and cybersecurity. CIDR (Classless Inter-Domain Routing) blocks provide a compact way to represent IP address ranges but handling them manually can be cumbersome. Enter the CIDR-Converter, a Go-based utility designed to simplify this process while supporting expanded input formats.
Check out my repo here:
pat-glitch
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cidr-converter
A CIDR block-converter
CIDR Convert
A command-line utility written in Go that processes, validates, and merges IP address ranges in various formats. The tool supports CIDR notation, wildcard notation, and multiple input/output formats.
Features
Input Processing
- Multiple input formats supported:
- CIDR notation (e.g., "192.168.1.0/24")
- Wildcard notation (e.g., "192.168.1.*")
- CSV files containing CIDR blocks
- JSON files containing CIDR blocks
- Interactive stdin mode for manual input
CIDR Operations
- Validates IP ranges and CIDR blocks
- Converts wildcard notation to CIDR format
- Merges overlapping CIDR blocks
- Sorts CIDR blocks for optimal organization
Output Handling
- Automatically saves merged results to JSON file
- Pretty-printed JSON output
- Comprehensive error handling and reporting
Installation
Ensure you have Go installed on your system, then:
git clone [repository-url] cd [repository-name] go build
Usage
The tool supports three input modes:
1. Standard Input Mode
git clone [repository-url] cd [repository-name] go build…
I'm also planning to create a web-app with additional features, to increase functionality and scope of the application!
This project was inspired by Andy Walker's cidr-convert repository.
Key Features
1. Flexible Input Formats
- Supports traditional CIDR notation (e.g., 192.168.0.0/24)
- Parses wildcard notations (e.g., 192.168..)
- Converts binary strings into CIDR blocks (e.g., 11000000101010000000000000000000/24)
- Reads CIDRs from CSV and JSON files
2. Intelligent Merging
- Merges overlapping CIDRs into a minimal set, reducing redundancy
- Aggregates smaller subnets into larger ones where feasible
3. File I/O Support
- Parses input from files or standard input
- Saves merged CIDRs to a JSON file for easy sharing and storage
The Problem It Solves
Handling large lists of CIDRs can be tedious, especially when dealing with overlapping or adjacent ranges. Manually aggregating these ranges is error-prone and time-consuming. This tool automates the process, ensuring optimal aggregation and reducing the risk of mismanagement.
How It Works
Core Functionalities
1. CIDR Parsing and Validation
The parseCIDR function ensures input conforms to valid CIDR notation.
2. Wildcard and Binary Parsing
- Wildcards (e.g., 192.168..) are converted into CIDRs by analyzing the mask length
- Binary strings (e.g., 11000000101010000000000000000000/24) are translated into IP addresses
3. CIDR Merging
- The mergeCIDRs function removes redundancy by merging overlapping ranges
- The aggregateCIDRs function combines smaller subnets into larger, encompassing blocks
4. File Parsing
Reads CIDRs from CSV and JSON formats using parseCSV and parseJSON functions.
5. Output
The merged CIDRs are saved to a JSON file for easy consumption by other tools or teams.
Example Usage
Command-Line Execution
Run the tool directly from the terminal, specifying input type:
git clone [repository-url] cd [repository-name] go build
Sample Output
Given the input:
./cidr-processor <span># Enter CIDR blocks interactively, one per line:</span> 192.168.1.0/24 10.0.0.* <span># Press Ctrl+D (Linux/Mac) or Ctrl+Z (Windows) to</span>
The tool outputs a single aggregated block:
# Standard input $ go run main.go Enter CIDR blocks, one per line. Press Ctrl+D (Linux/Mac) or Ctrl+Z (Windows) to end input: 192.168.0.0/24 192.168.1.0/24 # CSV Input $ go run main.go input.csv # JSON Input $ go run main.go input.json
Saved to merged_cidrs.json.
Code Walkthrough
Parsing Wildcard Notation
Wildcards like 192.168.. are converted into CIDRs:
192.168.0.0/24 192.168.1.0/24
The function calculates the appropriate prefix length and constructs a CIDR block.
Merging and Aggregation
The mergeCIDRs function eliminates redundancy:
[ "192.168.0.0/23" ]
Aggregation follows with:
git clone [repository-url] cd [repository-name] go build
This step combines adjacent ranges into larger blocks.
File Parsing
CSV and JSON input files are parsed with parseCSV and parseJSON, enabling seamless integration with existing workflows:
./cidr-processor <span># Enter CIDR blocks interactively, one per line:</span> 192.168.1.0/24 10.0.0.* <span># Press Ctrl+D (Linux/Mac) or Ctrl+Z (Windows) to</span>
Why Go?
Go's robust standard library, including packages like net, regexp, and encoding/json, makes it an excellent choice for building network-related tools. Its strong concurrency model ensures high performance, even with large datasets.
Future Enhancements
1. IPv6 Support
- Extend functionality to handle IPv6 ranges
2. Dynamic Input Formats
- Add support for YAML and XML
3. Web Interface
- Build a lightweight web application for interactive CIDR management
Conclusion
The Enhanced CIDR Block Calculator simplifies CIDR management with expanded input formats, intelligent merging, and robust file support. Its versatility makes it a valuable tool for network engineers, cloud architects, and cybersecurity professionals. Inspired by Andy Walker's cidr-convert, this tool builds upon foundational ideas to offer a more comprehensive solution. Give it a try and streamline your CIDR workflows today!
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