More screenshots
Works with the AI Agents you already use
Claude Code
Cursor
Codex CLI
Muse
Dots+22 moreClaude CodeCursorCodex CLIMuseDots
OpenClaw
Manus
Grok
Grok Bot+18 agentscloud subnet cidr planner
Size and pack VPC/VNet subnets for AWS, Azure or Google Cloud, catch overlapping ranges, and export the plan for Terraform.
$7
cloud subnet cidr planner
Example session with this skill installed
I'm building a new AWS VPC on 10.20.0.0/16 across us-east-1a, 1b and 1c. I need public subnets for about 60 load balancer and NAT IPs, private app subnets for up to 1,500 pod and instance IPs, data subnets for about 120, and one small management subnet for 20. Plan it with room to double, and give me something I can use in Terraform.
- Read your context and instructions
- Compiled the cloud subnet cidr
- Generated the data export
Plan for 10.20.0.0/16 (AWS: 5 reserved IPs per subnet, sized for 2x growth)
| Subnet | CIDR | Usable | Hosts | Headroom |
|---|---|---|---|---|
| private-us-east-1a / 1b / 1c | 10.20.0.0/20, 10.20.16.0/20, 10.20.32.0/20 | 4,091 each | 1,500 | 2,591 |
| data-us-east-1a / 1b / 1c | 10.20.48.0/24, 10.20.49.0/24, 10.20.50.0/24 | 251 each | 120 | 131 |
| public-us-east-1a / 1b / 1c | 10.20.51.0/25, 10.20.51.128/25, 10.20.52.0/25 | 123 each | 60 | 63 |
| mgmt-us-east-1a | 10.20.52.128/26 | 59 | 20 | 39 |
- Uses 13,504 of 65,536 addresses (20.6%). Free for later: 10.20.52.192/26, 10.20.53.0/24, 10.20.54.0/23, 10.20.56.0/21, 10.20.64.0/18 and 10.20.128.0/17. That's room for a whole extra zone or a new tier.
- Usable ranges skip AWS's reserved addresses (for example 10.20.0.4 to 10.20.15.254 in the first private subnet).
Files: plan.md (review), plan.csv, and subnets.tfvars.json. Use it with for_each = var.subnets on aws_subnet (example HCL in references/terraform-usage.md).
Before you build: send me your on-prem, VPN and other VPC ranges and I'll run an overlap check. Overlapping CIDRs can't be peered on AWS.
(Numbers come from a real run of the bundled script.)
plan.csv
CSV · data export
Example file from a real run - the skill writes it into your workspace.
Connects securely to your tools. The creator never sees your data.
About this skill
Get the subnet math right the first time. Subnets are hard to resize later.
cloud subnet cidr planner gives your AI agent a tested IP address planner instead of mental CIDR math. Tell it your cloud, your parent block, your availability zones and how many hosts each tier needs. It sizes every subnet with growth headroom, subtracts the addresses each cloud reserves, enforces each cloud's allowed subnet sizes, and packs everything into the block with no overlaps. You also get the free space left for later. A second command checks all your ranges (VPCs, on-prem, VPN, partners, Kubernetes pods) for overlaps that would break peering or VPN routing.
What it does
- plan: tiers like
public=60 private=1500 data=120, per zone or limited to fewer zones (mgmt=20/1), a growth factor (default x2), and an optional minimum subnet size. Output shows CIDR, first and last usable IP, usable count, hosts, the size each subnet was built for, headroom, and the remaining free blocks. - Cloud rules built in: AWS reserves 5 addresses per subnet (subnets /16 to /28, VPC blocks /16 to /28). Azure reserves 5 (subnets /29 to /2). Google Cloud reserves 4 in primary ranges (subnets /29 to /4). There's also a plain on-prem mode.
- When it doesn't fit: it tells you how many addresses you need and the smallest parent block that would work.
- overlap: identical, nested and partial overlaps across any list of named ranges, host-bit typos (
10.30.5.7/24is really10.30.5.0/24), CGNAT (100.64.0.0/10) and public-space warnings, and a collapsed summary of all space in use. - info and split: explain any block (netmask, range, usable IPs on each cloud, whether it's allowed as a subnet) or cut a block into equal subnets.
- Exports:
plan.mdfor review,plan.csv, andsubnets.tfvars.jsonthat drops into a Terraform/OpenTofufor_each. Example HCL for AWS, Azure and Google Cloud is included.
Problems it solves
- Off-by-one CIDR mistakes and forgetting each cloud's reserved addresses
- Subnets that run out of IPs when EKS/AKS/GKE pods, load balancers and endpoints start taking addresses
- New VPCs that overlap on-prem, a partner network or another VPC, and only show up when peering fails
- Fragmented address space with no room left for another zone or tier
- Hand-typing subnet CIDRs into Terraform
Who it's for
Cloud and DevOps engineers, platform teams, developers setting up their first production VPC, MSPs and consultants who design networks for clients, and anyone writing Terraform for AWS, Azure or Google Cloud networking.
What's included
SKILL.md: what to ask (counting pod IPs, endpoints and load balancers), run commands, how to present the plan, and what breaks when ranges overlapscripts/cidr_plan.py:plan,overlap,infoandsplitcommandsreferences/cloud-rules.md: each cloud's reserved addresses and allowed sizes with links to the official docs, plus the RFC address classesreferences/terraform-usage.md: using the JSON variables file with AWS, Azure and Google Cloud resourcesexamples/: a sample network list for overlap checks, an example plan and an example variables file
Standard-library Python only (ipaddress). No API keys, no cloud access, no network calls, no installs.
How to use
Skills on Agensi run inside your AI agent. Copy the prompt, paste it into your agent, and it connects to Agensi and installs this skill for you. If a payment is needed, your agent shows it to you first.
Reviews
No reviews yet
Be one of the first to try it. Every listed skill passes our trust checks below.
Security scanned
Passed our 8-point scan before listing
Fresh listing
Recently published to Agensi
Money-back guarantee
Doesn't do what its page promises? You get your money back.
Trust & safety
Security scanned
Verified clean 9 days ago
- Passed all security checks, Safe to install