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.
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.
curl -O https://raw.githubusercontent.com/DanielLavrushin/b4/main/.claude/skills/b4-issue/SKILL.mdgit clone --depth 1 https://github.com/DanielLavrushin/b4Wrote 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.
[](https://agentmods.dev/skills/daniellavrushin/b4/b4-issue)<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-issue"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-issue/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.
<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-issue"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-issue.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00132 | $0.01466 |
| Opus 5.5 | $0.00053 | $0.00586 |
| Sonnet 5.5 | $0.00026 | $0.00293 |
| Haiku 4.5 | $0.00013 | $0.00147 |
Grade A, and why
b4-issue scanned grade A with 1 finding 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 6d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
- **Third-party egress**: where the reporter tests from, and where the agent's own `curl` 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.
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.
- 6d ago First seen · 92 lines · 132 tokens per session scan A ddff340e0e90
b4-issue is a skill published in the GitHub repository DanielLavrushin/b4 (1,848 stars, last pushed 4d ago), licensed GPL-3.0. It adds 132 tokens to every session and 1,466 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-31.
b4-issue compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| b4-issueDanielLavrushin/b4 | Skill | 1.8k | 4d ago | GPL-3.0 | A | 132 | Claude Code |
| systematic-debuggingopen-metadata/OpenMetadata | Skill | 16k | yesterday | Apache-2.0 | A | 37 | Claude Code |
| log-error-digestzebbern/claude-code-guide | Skill | 4.7k | 3d ago | MIT | A | 71 | Claude Code, Codex |
| cwv-optimizeradobe/skills | Skill | 319 | yesterday | Apache-2.0 | A | 112 | Claude Code |
| ci-fixersipyourdrink-ltd/bernstein | Skill | 1.2k | yesterday | Apache-2.0 | A | 15 | Claude Code, Codex |
| incident-response-incident-responsermyndharis/antigravity-skills | Skill | 1.9k | 23d ago | MIT | A | 36 | Claude Code |
| triaging-web-analytics-supportPostHog/posthog | Skill | 41k | today | none | A | 151 | Claude Code, Codex |