Subnet Calculator (subcalc)

A powerful command-line subnet calculator that supports both Variable Length Subnet Mask (VLSM) and Fixed Length Subnet Mask (FLSM) calculations. Designed for network administrators, students, and anyone working with IP addressing and subnetting.

Features

• Network Information: Display detailed information about any IP network
• VLSM Calculation: Create optimally-sized subnets based on specific host requirements
• FLSM Calculation: Create equal-sized subnets based on either:
  • Number of required subnets
  • Specific prefix length
• Interactive Mode: User-friendly interactive input with command history and editing
• Command-line Mode: Scriptable operation for automation

Installation

Clone the repository

git clone https://github.com/nazdridoy/SubnetCalculator.git
cd SubnetCalculator

Make the script executable

chmod +x subcalc

Usage

Network Summary

Display detailed information about a network:

./subcalc --network 192.168.0.0/24

FLSM Subnet Calculation

Create equal-sized subnets in two ways:

1. By number of subnets:

./subcalc --network 192.168.0.0/24 --flsm 8

2. By specific prefix length:

./subcalc --network 192.168.0.0/24 --flsm /28

VLSM Subnet Calculation

Create optimally-sized subnets based on host requirements:

./subcalc --network 192.168.0.0/24 --vlsm 50 30 10 5

Interactive Mode

Run the tool interactively:

./subcalc --flsm     # For FLSM calculation
./subcalc --vlsm     # For VLSM calculation

Command-line Arguments

usage: subcalc [-h] [--network NETWORK] [--vlsm [VLSM ...]] [--flsm [FLSM]]

Subnet Calculator Tool - Calculate and display subnet information

options:
  -h, --help           show this help message and exit
  --network NETWORK    Base network address in CIDR notation (e.g., 192.168.0.0/24)
  --vlsm [VLSM ...]    Run Variable Length Subnet Mask calculator with specified host 
                       requirements (e.g., --vlsm 20 40 80)
  --flsm [FLSM]        Run Fixed Length Subnet Mask calculator with either number of 
                       subnets (e.g., --flsm 4) or target prefix length (e.g., --flsm /28)

Examples:
  ./subcalc --network 192.168.0.0/24                    # Display network summary
  ./subcalc --network 192.168.0.0/24 --flsm 16          # Create 16 equal-sized subnets
  ./subcalc --network 192.168.0.0/24 --flsm /28         # Create subnets with prefix /28
  ./subcalc --network 192.168.0.0/24 --vlsm 20 40 50    # Create subnets with specified host capacities
  ./subcalc --flsm                                      # Run FLSM in interactive mode
  ./subcalc --vlsm                                      # Run VLSM in interactive mode

Example Outputs

Network Summary

Network Summary for 192.168.0.0/24:
Network Address:     192.168.0.0
Broadcast Address:   192.168.0.255
Netmask:             255.255.255.0
Prefix Length:       /24
Number of Addresses: 256
Usable Hosts:        254
First Usable Host:   192.168.0.1
Last Usable Host:    192.168.0.254

FLSM Output

FLSM Summary:
Base Network:         192.168.0.0/24
Subnet Bits:          2
New Prefix Length:    /26
Subnet Mask:          255.255.255.192
Hosts per Subnet:     62
Requested Subnets:    3
Actual Subnets:       3
Unused Subnets:       1

+----------+------------------+-----------------+---------------+---------------+---------------+---------------+-------+
| Subnet   | CIDR Notation    | Subnet Mask     | Network ID    | Broadcast ID  | First Host IP | Last Host IP  | Hosts |
+----------+------------------+-----------------+---------------+---------------+---------------+---------------+-------+
| Subnet 1 | 192.168.0.0/26   | 255.255.255.192 | 192.168.0.0   | 192.168.0.63  | 192.168.0.1   | 192.168.0.62  | 62    |
+----------+------------------+-----------------+---------------+---------------+---------------+---------------+-------+
| Subnet 2 | 192.168.0.64/26  | 255.255.255.192 | 192.168.0.64  | 192.168.0.127 | 192.168.0.65  | 192.168.0.126 | 62    |
+----------+------------------+-----------------+---------------+---------------+---------------+---------------+-------+
| Subnet 3 | 192.168.0.128/26 | 255.255.255.192 | 192.168.0.128 | 192.168.0.191 | 192.168.0.129 | 192.168.0.190 | 62    |
+----------+------------------+-----------------+---------------+---------------+---------------+---------------+-------+

...

VLSM Output

+------------------+-----------------+---------------+---------------+---------------+---------------+--------------+-------------+
| Subnet           | Subnet Mask     | Network ID    | Broadcast ID  | First Host IP | Last Host IP  | Needed Hosts | Total Hosts |
+------------------+-----------------+---------------+---------------+---------------+---------------+--------------+-------------+
| 192.168.0.0/26   | 255.255.255.192 | 192.168.0.0   | 192.168.0.63  | 192.168.0.1   | 192.168.0.62  | 40           | 62          |
+------------------+-----------------+---------------+---------------+---------------+---------------+--------------+-------------+
| 192.168.0.64/26  | 255.255.255.192 | 192.168.0.64  | 192.168.0.127 | 192.168.0.65  | 192.168.0.126 | 50           | 62          |
+------------------+-----------------+---------------+---------------+---------------+---------------+--------------+-------------+
| 192.168.0.128/27 | 255.255.255.224 | 192.168.0.128 | 192.168.0.159 | 192.168.0.129 | 192.168.0.158 | 20           | 30          |
+------------------+-----------------+---------------+---------------+---------------+---------------+--------------+-------------+

...

Author

nazdridoy

Contributing

Contributions, issues, and feature requests are welcome!

License

This project is licensed under the MIT License. See the LICENSE file for details.