Ip Address Range Calculator

IP Address Range Calculator

function ipToLong(ip) { var parts = ip.split('.'); if (parts.length !== 4) return NaN; var longIp = 0; for (var i = 0; i < 4; i++) { var part = parseInt(parts[i], 10); if (isNaN(part) || part 255) return NaN; longIp = (longIp <>> 0; // Ensure unsigned 32-bit } function longToIp(longIp) { return ((longIp >>> 24) & 0xFF) + '.' + ((longIp >>> 16) & 0xFF) + '.' + ((longIp >>> 8) & 0xFF) + '.' + (longIp & 0xFF); } function calculateIpRange() { var ipAddressInput = document.getElementById('ipAddressInput').value.trim(); var cidrMaskInput = document.getElementById('cidrMaskInput').value.trim(); var resultDiv = document.getElementById('result'); var networkAddressResult = document.getElementById('networkAddressResult'); var broadcastAddressResult = document.getElementById('broadcastAddressResult'); var firstUsableIpResult = document.getElementById('firstUsableIpResult'); var lastUsableIpResult = document.getElementById('lastUsableIpResult'); var totalHostsResult = document.getElementById('totalHostsResult'); var usableHostsResult = document.getElementById('usableHostsResult'); var subnetMaskDecimalResult = document.getElementById('subnetMaskDecimalResult'); // Clear previous results networkAddressResult.innerHTML = 'Network Address: -'; broadcastAddressResult.innerHTML = 'Broadcast Address: -'; firstUsableIpResult.innerHTML = 'First Usable IP: -'; lastUsableIpResult.innerHTML = 'Last Usable IP: -'; totalHostsResult.innerHTML = 'Total Hosts: -'; usableHostsResult.innerHTML = 'Usable Hosts: -'; subnetMaskDecimalResult.innerHTML = 'Subnet Mask (Decimal): -'; // Validate IP Address var ipParts = ipAddressInput.split('.'); var isValidIp = true; if (ipParts.length !== 4) { isValidIp = false; } else { for (var i = 0; i < 4; i++) { var part = parseInt(ipParts[i], 10); if (isNaN(part) || part 255) { isValidIp = false; break; } } } if (!isValidIp) { resultDiv.innerHTML = '

Error: Invalid IP Address format. Please enter a valid IPv4 address (e.g., 192.168.1.0).

'; return; } // Validate CIDR Mask var cidr = parseInt(cidrMaskInput, 10); if (isNaN(cidr) || cidr 32) { resultDiv.innerHTML = '

Error: Invalid CIDR Subnet Mask. Please enter a number between 0 and 32.

'; return; } var ipLong = ipToLong(ipAddressInput); var subnetMaskLong = 0xFFFFFFFF << (32 – cidr); // Calculate subnet mask as a 32-bit integer var networkAddressLong = ipLong & subnetMaskLong; var broadcastAddressLong = networkAddressLong | (~subnetMaskLong); var totalHosts = Math.pow(2, (32 – cidr)); var usableHosts = 0; var firstUsableIp = 'N/A'; var lastUsableIp = 'N/A'; if (cidr === 32) { usableHosts = 0; firstUsableIp = longToIp(ipLong); lastUsableIp = longToIp(ipLong); } else if (cidr === 31) { usableHosts = 0; firstUsableIp = 'N/A (No usable hosts in /31)'; lastUsableIp = 'N/A (No usable hosts in /31)'; } else { usableHosts = totalHosts – 2; firstUsableIp = longToIp(networkAddressLong + 1); lastUsableIp = longToIp(broadcastAddressLong – 1); } networkAddressResult.innerHTML = 'Network Address: ' + longToIp(networkAddressLong); broadcastAddressResult.innerHTML = 'Broadcast Address: ' + longToIp(broadcastAddressLong); firstUsableIpResult.innerHTML = 'First Usable IP: ' + firstUsableIp; lastUsableIpResult.innerHTML = 'Last Usable IP: ' + lastUsableIp; totalHostsResult.innerHTML = 'Total Hosts: ' + totalHosts; usableHostsResult.innerHTML = 'Usable Hosts: ' + usableHosts; subnetMaskDecimalResult.innerHTML = 'Subnet Mask (Decimal): ' + longToIp(subnetMaskLong); } // Calculate on page load with default values window.onload = calculateIpRange;

Understanding IP Address Ranges and CIDR

An IP (Internet Protocol) address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It serves two main functions: host or network interface identification and location addressing. IPv4 addresses, the most common type, are 32-bit numbers typically displayed in dot-decimal notation (e.g., 192.168.1.1).

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and for IP routing. It was introduced in 1993 to replace the previous classful network addressing architecture in the Internet. CIDR allows for more efficient use of IPv4 addresses and helps to slow down the exhaustion of the IPv4 address space.

A CIDR notation appends a slash (/) and a decimal number to an IP address. This number, known as the CIDR prefix or subnet mask length, indicates the number of bits in the IP address that represent the network portion. The remaining bits represent the host portion.

For example, 192.168.1.0/24 means that the first 24 bits (192.168.1) identify the network, and the last 8 bits (.0) identify specific hosts within that network.

Key Components of an IP Address Range

When you define an IP address and a CIDR mask, you're essentially defining a specific network segment. Here are the critical components derived from this information:

• Network Address: This is the first IP address in a given network range. It's used to identify the network itself and cannot be assigned to a host. All host bits are set to 0.
• Broadcast Address: This is the last IP address in a given network range. Packets sent to this address are delivered to all hosts within that network segment. All host bits are set to 1.
• First Usable IP: This is the first IP address that can be assigned to a device (host) within the network. It's always one greater than the Network Address.
• Last Usable IP: This is the last IP address that can be assigned to a device (host) within the network. It's always one less than the Broadcast Address.
• Total Hosts: This is the total number of IP addresses available within the defined network range, including the network and broadcast addresses. It's calculated as 2^(32 - CIDR).
• Usable Hosts: This is the number of IP addresses that can actually be assigned to devices. For most networks, it's Total Hosts - 2 (subtracting the network and broadcast addresses). However, for /31 and /32 subnets, the number of usable hosts is 0.
• Subnet Mask (Decimal): This is the subnet mask represented in dot-decimal notation (e.g., 255.255.255.0 for a /24 mask). It helps to distinguish the network portion from the host portion of an IP address.

Example Calculation

Let's take the example of an IP address 192.168.10.50 with a CIDR mask of /27.

A /27 mask means 27 bits are for the network, and 32 - 27 = 5 bits are for hosts.

• Subnet Mask (Decimal): 255.255.255.224
• Total Hosts: 2^5 = 32
• Usable Hosts: 32 - 2 = 30

The network address for 192.168.10.50/27 would be 192.168.10.32.

The broadcast address for this network would be 192.168.10.63.

Therefore:

• Network Address: 192.168.10.32
• Broadcast Address: 192.168.10.63
• First Usable IP: 192.168.10.33
• Last Usable IP: 192.168.10.62
• Total Hosts: 32
• Usable Hosts: 30

This calculator simplifies the process of determining these critical network parameters, which is essential for network planning, troubleshooting, and security.