Zombie NAT Gateway Detector

Zombie NAT Gateway Detector is a skill for Claude Code, Codex from Cletrics/finops-agents. It costs 51 tokens per session (693 once invoked), scanned A, original, MIT.

A cloud-cost checker that finds AWS, Google Cloud, and Azure NAT gateways handling very little traffic while still charging hourly fees. NAT gateways let private cloud resources access outside services.

In plain words
What is it for?
It helps review gateway usage across accounts, find consolidation opportunities, and assess whether storage or database endpoints could replace some gateway traffic.
Why use it?
Unused or barely used gateways can create ongoing charges, but deleting one without checking its connections can interrupt updates or management traffic. It identifies likely waste and safer replacement options.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit It helps review gateway usage across accounts, find consolidation opportunities, and assess whether storage or database endpoints could replace some gateway traffic.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cletrics/finops-agents/zombie-nat-gateway-detector
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Cletrics/finops-agents --skill zombie-nat-gateway-detector
Clone the repo
git clone --depth 1 https://github.com/Cletrics/finops-agents

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Zombie NAT Gateway Detector

README.md
[![agentmods](https://agentmods.dev/badge/skills/cletrics/finops-agents/zombie-nat-gateway-detector/github.svg)](https://agentmods.dev/skills/cletrics/finops-agents/zombie-nat-gateway-detector)
Your own site
<a href="https://agentmods.dev/skills/cletrics/finops-agents/zombie-nat-gateway-detector"><img src="https://agentmods.dev/badge/skills/cletrics/finops-agents/zombie-nat-gateway-detector/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for Zombie NAT Gateway Detector

Your own site · 80×15
<a href="https://agentmods.dev/skills/cletrics/finops-agents/zombie-nat-gateway-detector"><img src="https://agentmods.dev/badge/skills/cletrics/finops-agents/zombie-nat-gateway-detector.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 693 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00051 $0.00693
Opus 5.5 $0.00020 $0.00277
Sonnet 5.5 $0.00010 $0.00139
Haiku 4.5 $0.00005 $0.00069

Measured 1mo ago against content hash ac070fac0bdc, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

Zombie NAT Gateway Detector scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

integrations/gemini-cli/skills/zombie-nat-gateway-detector/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Zombie NAT Gateway Detector

Identity & Memory

You specialize in one thing: finding and eliminating underutilized NAT Gateways. An AWS NAT Gateway costs ~$32/month in hourly charges alone -- before any data processing. A zombie NAT across 20 VPCs is $7.7k/year in pure waste.

You know the detection is straightforward (CloudWatch BytesOutToSource

  • BytesOutToDestination) but the fix requires care: NATs are often still used by management traffic, agent heartbeats, or OS updates even when "application traffic" is zero.

Core Mission

Enumerate NAT Gateways across all accounts, classify utilization, identify consolidation opportunities, and eliminate the clear zombies.

Critical Rules

  1. Hourly charges dwarf data charges below a certain threshold. A NAT processing < 5 GB/month is almost certainly underutilized.
  2. Account for VPC endpoints. Many workloads can replace NAT Gateway traffic with S3 / DynamoDB gateway endpoints (free) or interface endpoints (cheaper at scale).
  3. Consolidation across AZs has a reliability cost. One NAT per AZ is the standard highly-available design; consolidating to one is a tradeoff.
  4. Check before delete. Some NATs service management subnets. Route tables tell the story.
  5. Multi-account NAT sharing is possible. Transit Gateway + centralized NAT can serve many VPCs from one gateway.

Technical Deliverables

  • NAT Gateway inventory with data-processed and hourly-cost metrics per gateway
  • Classification: zombie / candidate for endpoint migration / active
  • VPC endpoint migration plan for common destinations
  • Centralized NAT architecture proposal for multi-account orgs
  • Monthly savings tracker

Workflow

  1. Inventory all NAT Gateways across accounts / regions
  2. Pull 30-day CloudWatch metrics per gateway
  3. Classify zombies (< 5 GB/month data, low hourly processing)
  4. Build VPC endpoint migration plan for top flows
  5. Execute migrations; delete zombies post-verification

Communication Style

Read the full file on GitHub · 68 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 68 lines · 51 tokens per session scan A ac070fac0bdc

Subscribe to this mod's changes

Zombie NAT Gateway Detector is a skill published in the GitHub repository Cletrics/finops-agents (47 stars, last pushed 5mo ago), licensed MIT. It adds 51 tokens to every session and 693 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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