Now it is perfectly fine to send the boot messages and start a login prompt on something else. For instance the Linux Kernel has a netconsole feature, to send the boot messages over the network to another Linux computer. It is also possible to send a copy of the boot messages, and start a login prompt on the serial port of the PC. We get then what is called a serial consoleIf you connect to this serial port any computing device with a terminal emulation program, it will be possible to work on the Linux PC as if you were using the PC locally in text mode. The requirements of the terminal emulation are quite low, so you could use HyperTerminal on a Windows PC, Minicom on Linux or even an old Atari ST with the appropriate program.
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In proxmox things work exactly the same, but with emulated devices. NoVNC/ VNC Applet connects to your VM keyboard and VM VGA display and displays the stuff you would expect from a real PC on a VGA display with a locally attached keyboard.Now we can also configure our VM to have an emulated serial port, and instruct the OS, to send a copy of the boot messages / start a login prompt on the emulated serial port.Once this is configured it will be possible to connect from the host (ie the server running pve) using a terminal emulation program, which is handily builtin in the Proxmox Qemu Manager.
You should have a look at ZOC, what I think to be the best terminal emulation program available for the Mac. I use it everyday for my job. It has the ability to do direct communication with a serial port. Of course it does way more than just serial communication.
"cs8" being the bit rate of router and "ixoff" specifying "No Flow Control". "115200" is the baud rate of router. Alternate settings would be "cs7" for 7 instead of 8 bit and "ixon" if flow control supported by your serial device. man screen
BTW, minicom -s (which would also need to be installed via macports or homebrew) also works great, but I prefer screen as I don't have to go through setup menus- I can just pass the serial connection parameters directly to the screen command.
In order to test sending and receiving serial data in PHP, the other end of the serial port should be open. On a windows system we recommend using Putty and on Mac OSX CoolTerm (see this FAQ for more details) to configure a serial for for transmitting and receiving data. We also recommend opening the other side of the serial connection in the terminal initially to confirm that data is definitely able to be sent and received across the connection.
Chapter 1 described how to connect the Arduino serial port to your computer to upload sketches. The upload process sends data from your computer to Arduino and Arduino sends status messages back to the computer to confirm the transfer is working. The recipes here show how you can use this communication link to send and receive any information between Arduino and your computer or another serial device.
Your Arduino sketch can use the serial port to indirectly access (usually via a proxy program written in a language like Processing) all the resources (memory, screen, keyboard, mouse, network connectivity, etc.) that your computer has. Your computer can also use the serial link to interact with sensors or other devices connected to Arduino.
Boards including the Uno, Duemilanove, Diecimila, Nano, and Mega have a chip to convert the hardware serial port on the Arduino chip to Universal Serial Bus (USB) for connection to the hardware serial port. Other boards, such as the Mini, Pro, Pro Mini, Boarduino, Sanguino, and Modern Device Bare Bones Board, do not have USB support and require an adapter for connecting to your computer that converts TTL to USB. See for more details on these boards.
The Arduino Mega has four hardware serial ports that can communicate with up to four different serial devices. Only one of these has a USB adapter built in (you could wire a USB-TTL adapter to any of the other serial ports). Table 4-1 shows the port names and pins used for all of the Mega serial ports.
You will usually use the built-in Arduino serial library to communicate with the hardware serial ports. Serial libraries simplify the use of the serial ports by insulating you from hardware complexities.
Sometimes you need more serial ports than the number of hardware serial ports available. If this is the case, you can use an additional library that uses software to emulate serial hardware. Recipes 4.13 and 4.14 show how to use a software serial library to communicate with multiple devices.
You can also send binary data using structures. Structures are a mechanism for organizing data, and if you are not already familiar with their use you may be better off sticking with the solutions described earlier. For those who are comfortable with the concept of structure pointers, the following is a function that will send the bytes within a structure to the serial port as binary data:
The draw function in Processing works like loop in Arduino; it is called repeatedly. The code in draw checks if data is available on the serial port; if so, bytes are read and converted to the integer value represented by the bytes. A rectangle is drawn based on the integer values received.
This sketch assumes that a serial LCD has been connected to pins 2 and 3 as shown in Figure 4-5, and that a serial console is connected to the built-in port. The loop will repeatedly display the same message on each:
As you did in Recipe 4.13, create a NewSoftSerial object in your sketch and tell it which pins to control. In the following example, we define a soft serial port called serial_gps, using pins 2 and 3 for receive and transmit, respectively:
If you installed Processing on the same computer that is running the Arduino IDE, the only other thing you need to do is identify the serial port in Processing. The following Processing sketch prints the serial ports available:
Set the variable portIndex to match the port used by Arduino. You can see the port numbers printed in the Processing text window (the area below the source code, not the separate Display window; see ). Recipe 1.4 describes how to find out which serial port your Arduino board is using.
First you'll want to find out which serial port your board is using. When you plug your board in to USB on your computer, it connects to a serial port. The port is like a door through which your board can communicate with your computer using USB.
In this guide, I'll show you how to connect your Raspberry Pi to a serial USB port and read its values with Python from the terminal (without a desktop environment). For this purpose, we'll use Pyserial and its terminal tool.
In this configuration, you can simply use the Pyserial miniterm tool to list available ports and their output. Use command python -m serial.tools.miniterm, then enter device port and receive port data on screen. Use CTRL+] to close connection:
Rasperry PI Zero W recommended PSU is at least 1,2 A.Typical bare board current consumption goes down to 150mA (Ref. -main-features-of-latest-rpi-models/). But for some projects (expecially if you want to power Arduino and external devices from Raspberry PI USB port) you may need more current capacity than the one RPI consumes alone. For this reason a bit higher power supply may be better. However also 2A is a good choise.Thank you for your feedback!
At the InfoSec Southwest 2013 conference I gave a presentation on serial port servers. This presentation was drawn from research that tried to determine how prevalent and exposed internet-connected serial port servers are. The results were pretty scary - authentication was rarely implemented and the types of devices exposed ranged from corporate VPN servers to traffic signal monitors. This post attempts to summarize that presentation, but the deck itself has more details. If you are unfamiliar with serial port servers or looking for some additional background, please consult the FAQ.
A typical serial port server is a box the size of a home router with one or more serial ports on one side and an ethernet, wireless, or mobile interface on the other. The serial port is connected to a target device, such as a router, server, or industrial control system, and the serial port server is configured to allow remote access to this port. Some examples of serial port servers are shown below.
In the first case, the serial port server requires some form of authentication before the user can interact with the serial-connected device. The most secure method is over a SSH session, but unless the attacker can eavesdrop on your connection, even telnet will do in a pinch.
In the second case, this is typically a clear-text TCP connection, accessed using the telnet command, and without any imposed authentication by the serial port server. If the serial-connected device requires authentication to access the serial console, this is the only layer of defense. The third case is usually identical, however some protocols (RealPort) can be configured to use both encryption and shared key authentication. In practice, however, these are mostly clear-text and unauthenticated as well.
In summary, we have a serial port exposed directly to the network. If the serial port is connected to a device that requires authentication, such as a Linux server, or a Cisco IOS router, it is theoretically protected from unauthorized access unless the attacker knows the correct password. Many serial devices do not require authentication and instead assume that if you are physically connected to a serial port, you probably have the right to configure the system.
Serial port servers change the authentication model in two significant ways. First, the concept of trusting a physical port goes out the window when that port is exposed to the internet, especially without an initial layer of authentication. Second, there is a significant difference between a SSH or telnet session and an authenticated serial console. If the user disconnects from SSH or telnet, the session is closed. This is not the case with serial consoles unless the device automatically logs out due to inactivity. Very few systems support inactivity timers on serial consoles (Cisco is one of the exceptions). An attacker just has to wait for a valid user to authenticate. Once logged in, the attacker can either hijack the serial port connection or wait for them to become idle and then steal a pre-authenticated shell on the target device. 2ff7e9595c
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