Subnet Calc

CIDR and subnet calculator for network engineers. Calculate network address, broadcast, host range, subnet mask, wildcard mask, and more from CIDR notation....

Security Scan

The skill's code, instructions, and requirements match its stated purpose (a CIDR/subnet calculator); it has no network calls, no secret access, and no install steps that would write arbitrary code to disk.

Purpose & Capability

Name/description, SKILL.md examples, and the included Python script all implement a CIDR/subnet calculator (IPv4/IPv6, split, containment). There are no unrelated dependencies or requested credentials.

Instruction Scope

SKILL.md instructs running the included script with arguments; the script only parses input, computes network properties using the stdlib ipaddress module, and prints results. It does not read unrelated files, environment variables, or transmit data externally.

Install Mechanism

No install spec or external downloads. The skill is instruction-only with one included Python script that uses only the Python standard library.

Credentials

No environment variables, credentials, or config paths are requested or used; this is proportionate for a local subnet calculator.

Persistence & Privilege

always is false and the skill does not request persistent system-wide changes or modify other skills. Allowing agent invocation is the platform default and is not problematic here.

Assessment

This appears to be a straightforward, self-contained Python subnet calculator. If you plan to run it, review the included script (scripts/subnet_calc.py) yourself (it’s short and uses only the stdlib), run it with Python 3 in a controlled environment, and avoid giving it any credentials or elevated filesystem permissions—none are required. If you need to run it as an autonomous agent skill, be comfortable with the agent being able to invoke the script (no additional privileges are requested).

CIDR/subnet calculator CLI. IPv4 and IPv6 support with no external dependencies.

Quick Start

# Basic subnet calculation
python3 scripts/subnet_calc.py 192.168.1.0/24

# JSON output
python3 scripts/subnet_calc.py 10.0.0.0/8 -f json

# Check if IP is in a network
python3 scripts/subnet_calc.py 172.16.0.0/16 --contains 172.16.5.10

# Split into smaller subnets
python3 scripts/subnet_calc.py 192.168.0.0/22 --split 24

# IPv6
python3 scripts/subnet_calc.py 2001:db8::/32

Output Fields (IPv4)

• CIDR — Normalized CIDR notation
• Network/Broadcast Address — First and last address in the range
• Subnet Mask / Wildcard Mask — Standard and inverted masks
• Total Addresses / Usable Hosts — Address count minus network and broadcast
• First/Last Host — Usable host range
• Binary representations — Network and mask in binary
• Flags — Private, loopback, multicast, link-local detection

Options

Flag	Description
-f, --format	plain or json output
--contains IP	Check if IP is within the network
--split PREFIX	Split into subnets with given prefix (IPv4)

Notes

• Python 3 stdlib only (uses ipaddress module)
• Handles /31 (RFC 3021 point-to-point) and /32 correctly
• Input is normalized with strict=False (host bits are masked)