network-interface-health

network-interface-health is a skill for Claude Code, Codex from nklofy/code-agent-skills. It costs 37 tokens per session (1,308 once invoked), scanned A, original, Apache-2.0.

A troubleshooting guide for network interface problems on routers, switches, and Linux hosts. It explains how to investigate errors, packet drops, CRC failures, duplex mismatches, link flapping, and speed negotiation.

In plain words
What is it for?
Use it to investigate packet loss and latency, compare both ends of a link, collect interface baselines, and check Linux link statistics and hardware counters.
Why use it?
It helps distinguish a faulty cable, optic, port, or setting from congestion or another network issue. Comparing counters over time gives better evidence than looking at one reading.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

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.

agentmods
npx agentmods add skills/nklofy/code-agent-skills/network-interface-health
Any agent
npx skills add nklofy/code-agent-skills --skill network-interface-health
Clone the repo
git clone --depth 1 https://github.com/nklofy/code-agent-skills

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 network-interface-health

README.md
[![agentmods](https://agentmods.dev/badge/skills/nklofy/code-agent-skills/network-interface-health.svg)](https://agentmods.dev/skills/nklofy/code-agent-skills/network-interface-health)
Your own site
<a href="https://agentmods.dev/skills/nklofy/code-agent-skills/network-interface-health"><img src="https://agentmods.dev/badge/skills/nklofy/code-agent-skills/network-interface-health.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,308 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00037 $0.01308
Opus 5 $0.00018 $0.00654
Sonnet 5 $0.00007 $0.00262
Haiku 4.5 $0.00004 $0.00131

Measured 2d ago against content hash 7811a643ffb8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

network-interface-health 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 2d 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.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

affaan-m-ECC/network-interface-health/SKILL.md · 154 lines

How it starts

The opening of the file, as written. The whole thing — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Network Interface Health

Use this skill when a network symptom might be caused by a physical link, switch port, cable, transceiver, duplex setting, or congested interface.

When to Use

  • A host or VLAN has packet loss, latency spikes, or intermittent reachability.
  • A switch or router interface shows CRCs, runts, giants, drops, resets, or flaps.
  • You need to compare both ends of a link before replacing hardware.
  • A change window needs before/after interface counter evidence.
  • Monitoring reports rising ifInErrors, ifOutErrors, or ifOutDiscards.

How It Works

Interface counters are evidence, but the trend matters more than the absolute number. Capture a baseline, wait a measurement interval, capture again, then compare increments.

show interfaces <interface>
show interfaces <interface> status
show logging | include <interface>|changed state|line protocol

On Linux hosts:

ip -s link show <interface>
ethtool <interface>
ethtool -S <interface>

Counter Reference

Counter Meaning Common cause
CRC Received frame checksum failed Bad cable, dirty fiber, bad optic, duplex mismatch
input errors Aggregate receive-side errors Check sub-counters before concluding
runts Frames below minimum Ethernet size Duplex mismatch, collision domain, faulty NIC
giants Frames larger than expected MTU MTU mismatch or jumbo-frame boundary
input drops Device could not accept inbound packets Burst, oversubscription, CPU path, queue pressure
output drops Egress queue discarded packets Congestion, QoS policy, undersized uplink
resets Interface hardware reset Flapping, keepalive, driver, optic, power
collisions Ethernet collision counter Half duplex or negotiation mismatch

Diagnosis Flow

CRCs Or Input Errors

  1. Confirm counters are incrementing, not just historical.
  2. Check both ends of the link. Receive-side errors usually point to the signal arriving on that side, not necessarily the port reporting the error.
  3. Replace patch cable or clean/replace fiber and optics.
  4. Confirm speed/duplex settings match on both sides.
  5. Check logs for flap events around the same timestamp.

Read the full file on GitHub · 154 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. 2d ago First seen · 154 lines · 37 tokens per session scan A 7811a643ffb8

Subscribe to this mod's changes

network-interface-health is a skill published in the GitHub repository nklofy/code-agent-skills (18 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 1,308 once invoked, about $0.0002 per session on Opus 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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