Analysis Results
Exposure Risk Score (Based on Subnet Size):
Network Scale Comparison (Log Scale)
Detailed CIDR Breakdown
| Parameter | Value | Description |
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Cloud CIDR Risk Calculator - IPv4
Understanding Cloud CIDR Risk and Subnet Calculations
The Cloud CIDR Risk Calculator transforms complex subnetting mathematics into actionable security insights. In cloud architecture (AWS, Azure, GCP), defining the correct Classless Inter-Domain Routing (CIDR) block is the foundation of network security. A subnet mask that is too large (e.g., /16) exposes a vast number of IP addresses to potential scanning, while a mask that is too small (e.g., /29) may limit scalability.
The Mathematics of Network Exposure
This calculator determines the Exposure Risk Score by analyzing the relationship between the subnet mask bits and the total addressable space. The formula for total hosts is \(2^{(32 - \text{mask})}\). As the mask value decreases, the host count grows exponentially, increasing the attack surface. For example:
- /24 Network: 256 IPs (Standard departmental size).
- /16 Network: 65,536 IPs (Enterprise VPC size).
Network administrators use this data to apply the Principle of Least Privilege at the network layer, ensuring subnets are sized precisely for their intended workload without unnecessary surplus.
Calculating Usable Hosts and Overhead
Beyond total capacity, network planning must account for reserved addresses. In standard IPv4 networking, every subnet sacrifices the first address (Network ID) and the last address (Broadcast IP), reducing the Usable Hosts count by 2. Furthermore, analyzing Protocol Overhead is vital for VPN tunnels. A standard TCP/IPv4 packet consumes 40 bytes of header space. Wrapping this in an IPSec tunnel adds approximately 80 bytes, significantly reducing the Maximum Transmission Unit (MTU) available for actual data payload.