VirtualBox Virtual Serial Port and Shared Host Machine Ports

# 1. Introduction to Virtual Serial Ports

## 1.1 Serial Port Concepts and Functions

A serial port, also known as a communication port, is an interface used for data transfer between devices. Serial ports are primarily used for data transmission between computers and external devices such as printers, mice, and keyboards. Serial communication can be simplex, half-duplex, or full-duplex, and it enables data transfer and communication between devices through the serial port.

In the realm of computing, serial ports can be implemented via traditional RS-232 interfaces or USB-to-serial adapters. Serial communication is known for its simplicity, stability, and cost-effectiveness, and it remains widely used in many scenarios.

## 1.2 The Role of Virtual Serial Ports in Virtualization Technology

Virtual serial ports are an integral part of virtualization technology, allowing virtual machines to communicate with the host machine (Host) or other virtual machines via serial communication. Through virtual serial ports, virtual machines can simulate hardware devices with serial port functionality, facilitating data transfer with external devices or other virtual machines.

The applications of virtual serial ports in virtualized environments are extensive, such as for debugging, data transfer, monitoring, and more. Virtual serial ports enable convenient serial communication between virtual machines or between a virtual machine and a physical machine, offering convenience for system management and development.

# 2. Introduction to VirtualBox's Virtual Serial Port Features

VirtualBox offers virtual serial port functionality, allowing virtual machines to communicate with the host or other virtual machines via serial ports. Here is a detailed introduction to VirtualBox's virtual serial port features:

- **2.1 Configuring Virtual Serial Ports**

Configuring a virtual serial port in VirtualBox requires the following steps:

1. Open the VirtualBox management interface, select the virtual machine to be configured, and click on Settings.
2. In the settings window, choose the Serial Ports tab, check the box to enable the serial port, and select the appropriate serial port mode (e.g., Host Pipe or Raw File).
3. For the Host Pipe mode, set the path and parameters for communication between the virtual machine and the host.
4. After confirming the settings, save and start the virtual machine; the serial port configuration is now complete.

- **2.2 Using Virtual Serial Ports in a Virtual Machine**

To use a virtual serial port in a virtual machine, typically follow these steps:

1. Install the appropriate serial communication software (such as minicom, HyperTerminal, etc.) in the virtual machine.
2. Configure the serial port parameters, including serial port number, baud rate, parity bits, etc.
3. Open the serial communication software and connect to the configured virtual serial port.
4. The virtual machine can now communicate with the host or other serial devices.

Below is a Python example code demonstrating how to use a virtual serial port for simple communication in a virtual machine:

import serial

# Configure virtual serial port parameters
ser = serial.Serial('COM1', 9600, timeout=1)

# Send data to the serial port
ser.write(b'Hello from virtual machine!')

# Receive data from the serial port and print it
data = ser.readline()
print(data.decode())

# Close the serial port connection
ser.close()

The above code utilizes the PySerial library to perform operations to open, write, read, and close a serial port, achieving the basic communication functionality of a virtual serial port.

Next, let's visually represent the configuration and usage process of virtual serial ports with a flowchart:

graph LR
     A(Open VirtualBox Management Interface) --> B(Select Virtual Machine and Click Settings)
     B --> C(Select Serial Ports Tab)
     C --> D(Check Enable Serial Port and Select Mode)
     D --> E(Configuring Path and Parameters)
     E --> F(Save Settings and Start Virtual Machine)

     G(Install Serial Communication Software) --> H(Set Serial Port Parameters)
     H --> I(Open Serial Communication Software)
     I --> J(Connect to Virtual Serial Port)
     J --> K(Perform Serial Communication)

This concludes the introduction to VirtualBox's virtual serial port features. By configuring and using virtual serial ports, we can enable serial communication between a virtual machine and the host or other external devices.

# 3. Shared Host Machine Port Settings

In VirtualBox, sharing host machine ports is a very useful feature that allows for the sharing and communication of ports between virtual machines and the host. Below we will detail the steps and methods for configuring shared host machine ports.

#### 3.1 What are Shared Host Machine Ports
Shared host machine ports refer to the association and sharing of a specific port on the host (such as serial ports, USB, etc.) with the correspon