What is cilium-host-policy?

A project guide for Cilium network policies and host firewalls in a Kubernetes cluster. Cilium controls which network traffic is allowed, including traffic between cluster nodes and essential management services.

Use it when adding or changing Cilium host policies, cluster-wide network policies, node selectors, or host-firewall settings.

It prevents a policy from accidentally blocking the Kubernetes API, node health checks, or other access needed to recover the cluster. The guide explains a default-deny setting that can affect every host policy.

How Aviator-Coding/home-ops configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to Aviator-Coding/home-ops. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/Aviator-Coding/home-ops/main/.agents/skills/cilium-host-policy/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/Aviator-Coding/home-ops

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/aviator-coding/home-ops/cilium-host-policy/github.svg)](https://agentmods.dev/skills/aviator-coding/home-ops/cilium-host-policy)

Your own site

<a href="https://agentmods.dev/skills/aviator-coding/home-ops/cilium-host-policy"><img src="https://agentmods.dev/badge/skills/aviator-coding/home-ops/cilium-host-policy/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/aviator-coding/home-ops/cilium-host-policy"><img src="https://agentmods.dev/badge/skills/aviator-coding/home-ops/cilium-host-policy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 815 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.

Model	Per session	Once invoked
Fable 5.1	$0.00069	$0.00815
Opus 5.5	$0.00028	$0.00326
Sonnet 5.5	$0.00014	$0.00163
Haiku 4.5	$0.00007	$0.00081

Measured 25d ago against content hash 432418c53563, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cilium-host-policy 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 25d 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.

.agents/skills/cilium-host-policy/SKILL.md · 36 lines

How it starts

The opening of the file, as written. The whole thing — 36 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cilium host firewall and CiliumClusterwideNetworkPolicy

Tripwires

A CiliumClusterwideNetworkPolicy with a nodeSelector and an ingress: or ingressDeny: must set enableDefaultDeny: {ingress: false}. The CRD defaults that direction to deny. The host endpoint then drops Talos API 50000/50001, Kubernetes API 6443, kubelet 10250, etcd, Cilium health, and BGP 179. Three Talos nodes, no SSH: physical console. Default-deny is OR-ed across policies, so one new CCNP re-arms it for every host policy. Set egress the same way when the policy has egress rules. gates.md
The nodeSelector must match a label that exists on the host endpoint, not merely on the Node. Cilium's default filter strips kubernetes.io/os and kubernetes.io/hostname. An unmatched selector is VALID: True, policy-enabled: none, and zero Deny rows. The live selector is node-role.kubernetes.io/control-plane Exists. kubernetes.io/os: linux matched nothing. evidence.md
Do not trust the policy until both halves of the bpf gate hold on every node. Deny rows for the Ceph ports, and Allow Ingress ANY still present. Missing Deny means the policy is inert and Ceph is still LAN-exposed. Missing Allow means the host is in default-deny: roll back before debugging. gates.md
Ceph daemons are host-network. spec.network.provider: host. A NetworkPolicy or CiliumNetworkPolicy in rook-ceph does not apply to them. Host policy is the layer that can.
The only live host policy is cilium/app/hostpolicy-ceph.yaml. enableDefaultDeny is false in both directions. policyAuditMode is false and hostFirewall.enabled is true, so it enforces. Do not add a second host policy that omits tripwire 1.

Where things live

What	Path
Host policy	`kubernetes/apps/base/kube-system/cilium/app/hostpolicy-ceph.yaml`
hostFirewall and policyAuditMode	`kubernetes/apps/base/kube-system/cilium/app/helmrelease.yaml`
Chart tag	`kubernetes/apps/base/kube-system/cilium/app/ocirepository.yaml`
Two-way gate and rollback	gates.md
Why the selector and the policy look the way they do	evidence.md
Selector gate	`scripts/ci/hostpolicy-ceph-selector-test.py`

Read the full file on GitHub · 36 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

25d ago Changed · +20 lines 432418c53563
1mo ago First seen · 16 lines · 69 tokens per session scan A 37ccf3b1e249

Subscribe to this mod's changes

cilium-host-policy is a skill published in the GitHub repository Aviator-Coding/home-ops (3 stars, last pushed today), licensed MIT. It adds 69 tokens to every session and 815 once invoked, about $0.0003 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 2026-09-04.

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home-ops: Skill for Claude Code