netcat-async

name	netcat-async
description	Maintain bidirectional netcat-style TCP communications with persistent asynchronous input/output. Use when Codex 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.

OpenCROW I/O - Netcat Async

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_send
  • session_read
  • session_status
  • session_stop
• Keep one named session per target flow so the MCP server can report stable artifacts under /tmp/codex-nc-async/<name>/.

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 session.
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

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

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

# 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.
• 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/codex-nc-async/<name>/:

• 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.