subnet-calc
# Subnet Calc
CIDR/subnet calculator CLI. IPv4 and IPv6 support with no external dependencies.
## Quick Start
```bash
# 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)
标签
skill
ai
