b4: Skill for Claude Code

.claude/skills/b4-hub/SKILL.md

b4-hub is a skill for Claude Code from DanielLavrushin/b4. It costs 125 tokens per session (1,300 once invoked), scanned A, original, GPL-3.0.

A workflow for changing b4hub, a separate Go-based community service with a command-line program, router API, moderation API, and web interface. It also covers the shared message format used between routers and the hub.

In plain words
What is it for?
Use it to modify the b4hub command-line tool, APIs, moderation console, web interface, or shared router and hub message format.
Why use it?
It keeps changes aligned across the service's separate code module, web interface, release boundaries, and router-to-hub communication. It also preserves established trust-model decisions.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is DanielLavrushin/b4's own configuration. It tells Claude Code how to work on b4 itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything b4 configures →

About the project

B4 is a Linux network packet-processing service that changes network traffic so deep packet inspection systems cannot identify or block its connections. It is used on routers, servers, and desktops to bypass DPI-based blocking, and a router installation can cover devices across the local network. The catalogue lists 12 skills associated with B4.

DanielLavrushin/b4 · 1,853 stars · on GitHub · docs.b4core.app

Reuse

Borrowing it

Nothing to install: this file belongs to DanielLavrushin/b4. 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/DanielLavrushin/b4/main/.claude/skills/b4-hub/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/DanielLavrushin/b4

Made for: Claude Code.

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 b4-hub

README.md
[![agentmods](https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-hub/github.svg)](https://agentmods.dev/skills/daniellavrushin/b4/b4-hub)
Your own site
<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-hub"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-hub/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 b4-hub

Your own site · 80×15
<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-hub"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-hub.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 125 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,300 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 unknown 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 $0.00125 $0.01300
Opus 5.5 $0.00050 $0.00520
Sonnet 5.5 $0.00025 $0.00260
Haiku 4.5 $0.00013 $0.00130

Measured 7d ago against content hash 6602f5439579, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

b4-hub 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 7d 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.

.claude/skills/b4-hub/SKILL.md · 90 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 7d ago First seen · 90 lines · 125 tokens per session scan A 6602f5439579

Subscribe to this mod's changes

b4-hub is a skill published in the GitHub repository DanielLavrushin/b4 (1,853 stars, last pushed yesterday), licensed GPL-3.0. It adds 125 tokens to every session and 1,300 once invoked, about $0.0005 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 2026-10-31.

Related

b4-hub compared with skills from other repositories

b4-hub next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
b4-hubDanielLavrushin/b4Skill1.9kyesterdayGPL-3.0A125Claude Code
mem0-oss-to-platformmem0ai/mem0Skill69kyesterdayApache-2.0A217Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skillsSkill3.2kyesterdayMITA78Claude Code
fastapi-router-pymicrosoft/skillsSkill3.2kyesterdayMITA46Claude Code
dev-runtimelangwatch/langwatchSkill5.0ktodayApache-2.0A172Claude Code
api-designericrisco/rsc-harnessSkill5293d agoMITA105Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1Skill253todayMITA106Claude Code