# Serial Proxy (MITM)

A small Python app that sits between the Arduino IDE and a real COM device. It creates (or uses) a **virtual COM port** that you open in the Arduino IDE, while it talks to the **real device** on another port. All traffic is **recorded** both ways and **passed through unchanged**.

## What it does

1. **CLI** — Lists connected COM ports; you choose the real device (e.g. your Arduino).
2. **Virtual port** — Tries to create a virtual COM pair with [com0com](https://sourceforge.net/projects/com0com/); if that fails, you pick one end of an existing pair.
3. **Relay** — Data from Arduino IDE → virtual port → this app → real device, and the reverse. No modification, only copying.
4. **Logging** — Every byte in both directions is logged to `serial_log.txt` (and optionally to the console) with timestamps and hex.

## Requirements

- Python 3.10+
- [pyserial](https://pypi.org/project/pyserial/): `pip install -r requirements.txt`
- **Virtual COM pair** (for “create virtual port” to work): install [com0com](https://sourceforge.net/projects/com0com/) and, if you want the app to create pairs automatically, run the script (or `setupc.exe`) with **Administrator** rights so it can create port pairs.

## Usage

1. Install dependencies:
   ```bash
   pip install -r requirements.txt
   ```
2. (Optional) Install com0com and, if needed, run the app as Administrator so it can create a virtual pair.
3. Run the proxy:
   ```bash
   python serial_proxy.py
   ```
4. Select the **real device** COM port (e.g. the actual Arduino).
5. If the app created a virtual pair, it will tell you which port to select in the Arduino IDE (e.g. COM252). Otherwise, select the end of the pair that **this app** will use; in the Arduino IDE you must select the **other** end of that pair.
6. Enter baud rate (default 115200) or press Enter.
7. In the Arduino IDE, choose the indicated virtual port and use Serial Monitor / upload as usual. All traffic is logged to `serial_log.txt`.

Stop with **Ctrl+C**.

## Log file

- Path: `serial_log.txt` in the same folder as `serial_proxy.py`.
- Each line has timestamp, direction (`IDE->device` or `device->IDE`), byte count, hex dump, and a raw repr of the bytes.

## Without com0com

If you don’t install com0com, the app cannot create a virtual pair. You’ll need another way to get a **pair** of linked virtual ports (e.g. another null-modem/virtual serial driver). Then run the app, select the **real** device port, and when asked, select the port that **this app** should open (one end of the pair). Use the **other** end of that pair in the Arduino IDE.

## Summary

| You select in the app | You select in Arduino IDE |
|------------------------|----------------------------|
| Real device (e.g. COM3) | — |
| Virtual port “for this app” (e.g. COM251) | The **other** end of the pair (e.g. COM252) |

Traffic flows: **Arduino IDE ↔ virtual pair ↔ this app ↔ real device**, with full logging both ways.