# Netcat Async

> Maintain bidirectional netcat-style TCP communications with persistent asynchronous input/output. Use when an agent must keep a connection open across multiple commands, send messages while receiving background output, inspect connection logs, or safely start/stop reusable sessions for protocol testing, CTF services, debugging sockets, or interactive line-based services.

- **Type:** Skill
- **Install:** `agentstack add skill-02loveslollipop-opencrow-netcat-async`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [02loveslollipop](https://agentstack.voostack.com/s/02loveslollipop)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [02loveslollipop](https://github.com/02loveslollipop)
- **Source:** https://github.com/02loveslollipop/OpenCROW/tree/main/skills/netcat-async

## Install

```sh
agentstack add skill-02loveslollipop-opencrow-netcat-async
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# OpenCROW I/O - Netcat Async

## Runtime preflight

Probe required commands with `command -v` and Python modules with `importlib.util.find_spec` before use. Prefer a PATH-resolved OpenCROW MCP helper or the `ctf`/`sage` environment when available, then the managed helper or system Python. If a capability is missing, stop that path safely and report the exact missing command or module.

Prefer the `opencrow-netcat-mcp` server for session lifecycle, reads, and writes. Fall back to `scripts/ncx` only when you need to inspect or debug the backend directly.

## MCP First

- Use `toolbox_info`, `toolbox_verify`, and `toolbox_capabilities` first.
- Use the generic session tools:
  - `session_start`
  - `session_listen`
  - `session_send`
  - `session_read`
  - `session_status`
  - `session_stop`
- Keep one named session per target flow so the MCP server can report stable artifacts under `/tmp/opencrow-nc-async//`.

Use `scripts/ncx` to manage long-lived TCP sessions instead of one-shot `nc` invocations when you are operating outside MCP.

## Workflow

1. Start a named outbound session, or listen for one inbound connection.
2. Send one or more payloads while the daemon keeps receiving output asynchronously.
3. Read logs (`tail` for recent data, `follow` for streaming).
4. Stop the session when done.

## Commands

```bash
# Start session
scripts/ncx start --name demo --host 127.0.0.1 --port 9001

# Listen on loopback for one inbound connection (port 0 selects a free port)
scripts/ncx listen --name inbound --port 0

# Send text (append newline for line-oriented protocols)
scripts/ncx send --name demo --data 'ping' --newline

# Send exact bytes using hex or strict base64
scripts/ncx send --name demo --hex '00 03 ff'

# Read latest output
scripts/ncx read --name demo --tail 40

# Follow output live
scripts/ncx read --name demo --follow

# Check metadata and process state
scripts/ncx status --name demo

# Stop session
scripts/ncx stop --name demo
```

## Operational Rules

- Use one session per target/service flow (`--name` scoped per host+port interaction).
- Prefer `--newline` for interactive text protocols.
- Non-loopback listeners require `--allow-remote`; restrict known peers with `--expected-peer`.
- Read with `--tail` before `--follow` to avoid missing context.
- Stop sessions explicitly to avoid stale daemons.
- If `status` reports `running: false`, inspect `daemon.log` and restart.

## Files and State

Session state lives at `/tmp/opencrow-nc-async//`:

- `io.log`: timestamped TX/RX events
- `rx.raw`: raw received bytes
- `daemon.log`: daemon stdout/stderr
- `meta.json`: session metadata
- `pid`: daemon PID

## References

- For usage patterns and recovery steps, read `references/patterns.md`.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [02loveslollipop](https://github.com/02loveslollipop)
- **Source:** [02loveslollipop/OpenCROW](https://github.com/02loveslollipop/OpenCROW)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-02loveslollipop-opencrow-netcat-async
- Seller: https://agentstack.voostack.com/s/02loveslollipop
- Browse the marketplace: https://agentstack.voostack.com/browse

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