Emulate printer via inline usb port - linux

I need to emulate/fake a printer (any printer) that is connected through a usb port without touching the hosting computer. The connection needs to be via some kind of inline connection.
What i mean is to connect something to the hosting computer usb port and connect the printer to that device on another port (or on wifi). The computer that will send the printing should not know the difference when sending a printing job and also no software should be installed on the printing computer.
I need it in order to add text to the print jobs (whether they are in PCL/Postcript/Any other format) in various places based on the text being printed.
I've found the Red Titan solution, but it's working on windows and I rather work on a Linux environment.
If there is a Linux software that can emulate a printer port and can be customized for any printer type, I could just program a Raspberry Pi/Any other device to do all the conversions and editing and send it to the printer.
I just haven't found any software that could do that via an inline usb.
Any help would be appreciated!

Related

How to create a dummy "pipe" pseudo-serial device on Linux?

I need to write a program (C++) that uses a serial port to communicate with another device. The other device isn't even built yet so I need a software emulator For various reasons there is no point going into here, the software emulator needs to run on a different machine. I would like to send the data via UDP from the software emulator to the machine my program is running on and have it received by another serial interface type program that in some way acts as a serial port (serial tty device).
I also want to test my program in an automated fashion in a VM. Ideally my test program would also use UDP and would use the same UDP-serial interface program to forward the data back and forwards between my test program and the program under test.
Time is very tight. I don't really have time to learn to write and install kernel level device drivers.
I would be very grateful for any pointers as to how I can create some sort of "pipe" or "loopback" pseudo-serial device.
I am working on Linux.
Credit to meuh for his tip-off.
socat UDP:127.0.0.1:5001,bind=127.0.0.1:5000 \
PTY,link=/dev/ttyS0,raw,echo=0,waitslave
This listens on UDP port 5000 on the loopback network interface. All data received is sent to the virtual serial device at /dev/ttyS0. All data received on the virtual serial device is sent to UDP address 127.0.0.1:5001.
The IP address can be remote.
The command must be run as root, as must the process connecting to the serial port. To avoid this use a different file path, e.g. /tmp/ttyS99.
Apparently the file path specified must not already exist. However my PC has /dev/ttyS0 all the way to /dev/ttyS31 despite not having any serial ports, and using /dev/ttyS0 works fine. I suppose if I actually had a real serial port this wouldn't work.

Device to divert printing to PDF

I'm trying to build a device that is inserted between a client and a printer.
In the normal case this device should just allow the printing to occur as normal, but if a certain event happens it should instead divert the printing to a PDF file on disk.
In essence it should work as a print server that can decide where to send the data to be printed.
The problem is that I want to achieve this using an USB-A to USB-A cable between the client and the device, and the printer via USB to the device.
The device is at the moment a Raspberry Pie running Raspbian.
Printing from the Pie is tested using CUPS, so that works.
Now for the question(s):
How can I allow printing via USB cable from the client? Simply connecting the device and the client does not allow it to be recognised as a printer. CUPS does not seem to support this sharing option.
Can CUPS be configured to support sharing via USB?
Is there any other print software that supports this?
Is there another OS where this could be achieved easier?
Any input is appreciated!

Reading Bluetooth data and command (Raspberry pi 3)

I am currently working on a project that make me control media center and a few domotic parts in my living room.
I have connected on my raspberry pi 3 a NAS, my Spotify account (with hifiberry, controls to close my amp, my PC and a few lights...
At first to control it all I programmed a web server that I can access on my phone. That made the job but it is not completely user friendly since I have to have my phone go to the interface and do whatever I have to... And I'm not a web designer 😁 it's far from perfect!
I've made some research and I have decided to build a bluetooth remote control (raspberry pi 3 do have Bluetooth low energy).
Since nothing exist as I want, it is going to be a custom one made with Arduino mini and hm10 module.
But I'm stuck on the raspberry part!
How can I read the Bluetooth data send by my remote and launch scripts according to the command sent?
Via a serial listener of some kind?
Yes, in fact, you should use a serial port to connect your pi with Bluetooth module.
You then use software input information for your purposes, but you must first implement the hardware and hardware interface first.
You can build application software with the Python programming language.

Use a Linux Computer as a USB Coupler

I am on debian and:
I have a USB controller hooked up to a USB port on my PC (Device 1).
I have a male to male USB cord hooked up to another port on the PC that connects to Device 2. (it is a "bridging" usb cord, and has the chip for it)
I want to make them connect to each other as if they were one cord, so neither device knows that there is a computer in the middle.
This would be called a 'Coupler', except that I am using a PC as a coupler.
Here is a (really bad) diagram I made:
What I have done:
I have been able to connect the two devices independently of each other and sniff the results for when they fail to connect. The devices don't send a large volume of data back and forth.
Maybe there is some kind of command tool that I could use, for example (psudocode):
$ couple-usb-ports PORT1 PORT2
You're trying to reinvent the wheel here.
You might consider looking at this link instead.
http://dan3lmi.blogspot.com/2012/10/sniffing-usb-traffic-different.html
Specifically this.
Windows: You cannot directly capture raw USB traffic on Windows with Wireshark/WinPcap, but it is possible to capture and debug USB traffic on a virtual Windows machine under Oracle Virtual Box.
You cannot use a simple PC as transparent USB sniffer without extra (expensive) hardware. An USB bus has always one host (and one or more devices), and the PC can only be the host. This is a hardware limitation.
But you can capture USB data in a Windows machine using Wireshark and USBPcap, eliminating the need for the middle box in most cases.
As this post is tagged Linux, I suppose the controller PC is a Linux machine. Instead of connecting USB ports with a male-male connector, which is all kinds of bad (you are connecting the 5V lines of both machine with each other!), just run Wireshark in the controller PC.
There might be a little work to be done previously, as you have to enable Wireshark for USB monitoring (Particularly in Debian, this is disabled by default), and you might have to install a small driver to enable the monitoring. Have a look at this page for more information.
Once you get it working, Wireshark is an excellent tool for this!

Sniffing IOCTL and serial port communication

I'm trying to reverse the protocol used by an early nineties logic analyzer an its PC software.
The device is connected via RS-232 (propietary wiring) and communicates with a DOS program, successfully running on DOSBOX.
I'm able to control the device with the original software but it would be useful to autimathe the downloading of data from the analyzer using a custom program but to do so I need to know what is going on the serial port.
Ineed to know what mode is the serial port set, while I know for sure the datarate is either 1200 or 9600 bps (configurable on the device) I don't know the flow control (I guess it is RTS/CTS).
I also need to tap into the conversation between the prgram and the device without disturbing their communication.
Reading the serial port with another program (cutecom/minicom) prevents the emulator from receiving the data from the hardware.
So, summing up, what I need to know is:
What configuration is set on /dev/ttyS0 (via IOCTL calls, i think)
What goes on between program and device.
I was thinking in programming a library which acts as a proxy for the standard c library (via LD_PRELOAD) but there must be an easier way to do this.
You can use slsnif (Serial Line SNIFfer).
http://linux.die.net/man/1/slsnif
Here's a link to the sourceforge project so you can download it. I don't believe it comes with any modern distributions but I could be wrong so check your distro's software repository first.
http://sourceforge.net/projects/slsnif/
I use ttyrpld for tty sniffing. I ported it to PPC and run it on 2.6.32. It logs all of the tty traffic on the board to files, one per tty. Works well.

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