https://github.com/jaketrogers/subnetcalc
subnet calculator
https://github.com/jaketrogers/subnetcalc
cobra-cli golang network networking utility
Last synced: 6 months ago
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subnet calculator
- Host: GitHub
- URL: https://github.com/jaketrogers/subnetcalc
- Owner: JakeTRogers
- License: apache-2.0
- Created: 2023-07-14T23:58:39.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2025-08-18T22:24:57.000Z (10 months ago)
- Last Synced: 2025-08-21T08:01:33.634Z (10 months ago)
- Topics: cobra-cli, golang, network, networking, utility
- Language: Go
- Homepage:
- Size: 193 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
# subnetCalc
## Description
This is a Go CLI utility (built with [Cobra](https://github.com/spf13/cobra)) to calculate network information from a CIDR.
It can also split a “supernet” into smaller subnets and render the result either as a styled table or JSON. There is also an optional interactive TUI for splitting/joining subnets.
IPv4 is the primary target. IPv6 works for basic calculations/output, but deeper functionality (especially around very large splits) is intentionally limited.
## Usage
`subnetCalc /`
### Flags
- `--subnet-size`, `-s` — split the input network into subnets of this prefix length
- `--json`, `-j` — output JSON
- `--interactive`, `-i` — launch the interactive TUI (mutually exclusive with `--json`)
- `--verbose`, `-v` — increase verbosity (repeat for more)
### Interactive TUI Key Bindings
When using `--interactive` mode:
- `↑/k` — move cursor up
- `↓/j` — move cursor down
- `←/h` — scroll split columns left
- `→/l` — scroll split columns right
- `pgup` — page up through rows
- `pgdn` — page down through rows
- `s` — split selected subnet
- `x` — join selected subnet with sibling
- `u` — undo last split/join operation
- `r` — redo last undone operation
- `e` — export tree as JSON
- `c` — copy JSON to clipboard
- `?` — toggle help display
- `q` — quit
## Examples
### List /12 Subnets Contained in a /8 Network Using the Interactive TUI
### Get Network Information for a /19 Network
`subnetCalc 10.12.34.56/19`
```text
Network: 10.12.32.0/19
Host Address Range: 10.12.32.1 - 10.12.63.254
Broadcast Address: 10.12.63.255
Subnet Mask: 255.255.224.0
Maximum Hosts: 8,190
```
### List /27 Subnets Contained in a /25 Network
`subnetCalc 192.168.10.0/25 --subnet-size 27`
```text
Network: 192.168.10.0/25
Host Address Range: 192.168.10.1 - 192.168.10.126
Broadcast Address: 192.168.10.127
Subnet Mask: 255.255.255.128
Maximum Hosts: 126
192.168.10.0/25 contains 4 /27 subnets:
╭──────────────────────────────────────────────────────────────────────────────────────────────────╮
│ # Subnet Subnet Mask Assignable Range Broadcast Hosts │
│1 192.168.10.0/27 255.255.255.224 192.168.10.1 - 192.168.10.30 192.168.10.31 30 │
│2 192.168.10.32/27 255.255.255.224 192.168.10.33 - 192.168.10.62 192.168.10.63 30 │
│3 192.168.10.64/27 255.255.255.224 192.168.10.65 - 192.168.10.94 192.168.10.95 30 │
│4 192.168.10.96/27 255.255.255.224 192.168.10.97 - 192.168.10.126192.168.10.127 30 │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
```
### List /20 Subnets Contained in a /19 Network in JSON Format
`subnetCalc 10.12.34.56/19 --subnet-size 20 --json`
```json
{
"cidr": "10.12.32.0/19",
"firstIP": "10.12.32.1",
"lastIP": "10.12.63.254",
"networkAddr": "10.12.32.0",
"broadcastAddr": "10.12.63.255",
"subnetMask": "255.255.224.0",
"maskBits": 19,
"maxHosts": "8,190",
"subnets": [
{
"cidr": "10.12.32.0/20",
"firstIP": "10.12.32.1",
"lastIP": "10.12.47.254",
"networkAddr": "10.12.32.0",
"broadcastAddr": "10.12.47.255",
"subnetMask": "255.255.240.0",
"maskBits": 20,
"maxHosts": "4,094"
},
{
"cidr": "10.12.48.0/20",
"firstIP": "10.12.48.1",
"lastIP": "10.12.63.254",
"networkAddr": "10.12.48.0",
"broadcastAddr": "10.12.63.255",
"subnetMask": "255.255.240.0",
"maskBits": 20,
"maxHosts": "4,094"
}
]
}
```
## Notes / Limitations
- `--subnet-size` will refuse to generate an extremely large number of subnets (currently capped at 1,000,000) to avoid accidental OOM/hangs.
- IPv6 output is supported, but some concepts (like “broadcast”) are displayed as the last address in the range.
## Feedback
Bug reports, feature requests, and pull requests are welcome but may not be responded to in an even remotely timely manner.