re-ws.pl – ReverseEngineering WorkStation

How to recover torrent from rtorrent meta files

Posted on May 27, 2024 - May 28, 2024 by Kamil (aka. v3l0c1r4pt0r)

meta2torrent result in torrent file editor

rtorrent is very nice tool to download torrents quickly and on headless systems. However, while making such a quick use, I was caught by its weird design decision that it comes unconfigured and while not configured explicitly it does not store its session in any way, even as torrent files of jobs that were started. I can imagine that in many cases it is not a problem as still usually torrent files are easily available and if not using magnet to obtain one is not a problem. Unfortunately I ran into such a weird situation where I was not able to start a job again with just a magnet link and obviously was not able to download whole torrent at one run. Also saving session in rtorrent was not working. So the only chance for me to recover download job was to use meta file that rtorrent leaves behind for reason unknown. There is even Github issue discussing those files and requesting ability to use them to recover the job. But unfortunately it is still open. So the only way for me was to do it myself. Continue reading “How to recover torrent from rtorrent meta files” →

Connecting WMS services to apps able to handle only OpenStreetMap format like OsmAnd Android app

Posted on July 1, 2023 by Kamil (aka. v3l0c1r4pt0r)

So thing is that there is a lot of interesting map data provided by state institutions (at least here in Europe), but at the same time viewer that at least Polish Geoportal provides does not provide experience good enough for everyone (that is my personal opinion) and at the same time there exist cool Android app that is able to integrate many different map providers and for some reason include neither WMS, nor WMTS support. And these two are core of services like mentioned Geoportal and seems like a standard for GIS purposes. As this seemed to me like a nice, little and easy side project, I took an opportunity. What I did is basically a wrapper that takes format used by OSM (called Slippy Map) and generates WMS-compatible request under the hood. But as you, the user, are here, you probably are not interested that much in technical details, but rather seek a solution to the problem that I had. So, here it is.

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Pinout of laser driver for CPRI SFP+ module – GN1157

Posted on October 15, 2022 by Kamil (aka. v3l0c1r4pt0r)

On one of the usual sources of weird electronics I came across quiet unusual SFP+ module and could not resist buying it to see how it works. For now I was unable to make it work, but at least I made few photos of its internals. It turned out its main part is obscure chip made by Semtech and described as GN1157, which serves as laser diode driver. Obviously obtaining datasheet is impossible even in China. However, thanks to being able to see the board, I was able to reverse engineer some part of its pinout. Continue reading “Pinout of laser driver for CPRI SFP+ module – GN1157” →

Sniffing USB traffic with DSLogic logic analyzer into pcap file

Posted on August 3, 2022 - August 29, 2022 by Kamil (aka. v3l0c1r4pt0r)

Lately I came back to reverse engineering project that I started few years ago. Direct reason for such a long break was being stuck at attempts in using usbmon to capture USB traffic. The traffic that I wanted to sniff was between router and modem that connects to it via USB. As is usual with this kind of devices there is no SDK available and compiling custom kernel module for such system, while has huge educational value, is most likely going to end up with failure. So definitely I needed another way around this problem. Fortunately I have DSLogic logic analyzer, that could easily record such a slow protocol as USB. Then a bit of exporting and you get pcap file for wireshark. This might sound like a simple task, but I am going to show that it is not necessarily is. Continue reading “Sniffing USB traffic with DSLogic logic analyzer into pcap file” →

New ccfactory on its way, binutils are already here

Posted on July 16, 2021 - July 16, 2021 by Kamil (aka. v3l0c1r4pt0r)

From the beginning of current year I am learning Docker. First result of this interest on my Github was publishing ccfactory tool, which was supposed to provide easy way to produce compiler toolchains. Almost like they were mass-produced in a factory, thus the name. However, since then I learned a lot and gained some experience. At the moment it is obvious to me, what I did then is not the best design. And because the project is still very fresh, I decided to start once again, from scratch, to create way better design that will be easy to develop and maintain.

Today is time to publish first step to this new design – binutils. I would not do that, but Docker Hub allows to have only one private repo, so the way that I do it disallows me to have it private anyway. So better idea is to describe it somehow to avoid confusion. As I wrote, this first step is binutils and this is simple container that contains binutils and nothing else. My goal is to finally make toolchain base on gcc version 3.3, which might sound weird, but this is what I needed in the past and is best way to prove what this new approach can achieve. With previous one, that I will call legacy from now on, I failed in that and before failing I did even more complicated Dockerfile, than originally planned. So, when finished this one will be proof of good design, I hope. Continue reading “New ccfactory on its way, binutils are already here” →

Unboxing, startup and first impression of Nezha board marketed as first affordable RISCV SBC

Posted on July 6, 2021 by Kamil (aka. v3l0c1r4pt0r)

Some of you may have already heard about new RISCV board that popped up in China recently. It is called Nezha and is the first available SBC having new Allwinner D1 SoC with RISCV core and capable of running Linux. Authors are marketing it as first affordable RISCV Linux SBC and there is a lot of truth in these claims. Maybe this board cannot compete in any way with boards based on ARM Cortex A cores. On the other hand all previous RISCV offerings were in different galaxy in terms of price tag. $999 for Hifive Unleashed during its Crowdsupply campaign vs. $99 for Nezha on Indiegogo. They even claimed to go down as low as to $12, but as they say global supply chain problems made it impossible for now. We have to wait for all this pandemic troubles to end to check, if these claims could be verified by facts. Continue reading “Unboxing, startup and first impression of Nezha board marketed as first affordable RISCV SBC” →

Docker image with just cURL

Posted on June 7, 2021 by Kamil (aka. v3l0c1r4pt0r)

Lately I play a bit with Docker containers. In a chain of problems that I have right now, I needed to have static cURL library on Debian. As it turned out linking cURL statically is not an easy task. Rather it causes a lot of problems, especially when trying this with packages available in Debian repos. After a long fight with these I decided to prepare my own distribution of cURL. But instead of creating usual deb package, I did it all on Docker and as a result, I have Docker image. In it I utilized possibilities of staged builds, where there can be few steps having in common only certain files. As a result I created base image, means the one created from scratch, where there are no other files, than the ones that we provide. So I provided only complete cURL install directory and musl libc to be able to run curl binary, as I did not want to tinker with cURL’s build system even more, than I did. Final image weights only ~1,5 MiB, so a result is really nice space saving compared to usual approach to Docker images. Inside, you can run curl binary separated from your operating system (to extent that Docker provides – remember, it is not virtualization!). Also it is possible to use libcurl to link your own binaries with it, this time completely statically!

As always, sources are on Github and this time there are also ready-to-use images on Docker Hub, so you can pull them directly, without need to build them. All instructions are on both pages and this is nothing unusual for any user of Docker, so I will not repeat myself here.

uCM4 – really small CM4 carrier board for network projects

Posted on May 22, 2021 - May 22, 2021 by Kamil (aka. v3l0c1r4pt0r)

Few days back I published a hint that I am working on some hardware project, that utilized some networking, by publishing KiCAD footprints of connectors that I use. Now the time has come to reveal all the details. This was possible due to board being basically working.

And the project is Raspberry Pi Compute Module 4 carrier/base board. Just to give a brief here, it is a board that is meant to allow connecting CM4 SoM modules to network and take as little space as practically possible. I would call this device smallest possible CM4 carrier board, but then probably somebody will prove me wrong by designing something smaller. But to still be practical, it is almost the smallest it could, as it is exactly same footprint as CM4 itself. By making it even smaller, I would have to remove mounting holes, as they are exactly at the edges.

Getting to the interesting part, it is meant to connect to Ethernet and allow you to do whatever you like. The only thing you need to connect beside Ethernet is power via Micro USB connector. Worth to mention is that this is requirement of this particular iteration of the board, as it should be fairly easy to redesign it a bit to use PoE instead. Anyway, comparing to traditional Raspberry Pi, you get a lot of saved space at a cost of only 3 connector available (not counting UART header). And third, not mentioned yet, is microSD card slot, that is completely optional, but present in my case, as I use CM4Lite variant with no storage, so this is rather a useful feature. Getting rid of this requirement on CM4Lite SoMs might be a subject of future research from my side, as I heard about network boot on RPi, but have not tried it myself yet. Continue reading “uCM4 – really small CM4 carrier board for network projects” →

My small library of KiCAD footprints

Posted on May 16, 2021 - May 16, 2021 by Kamil (aka. v3l0c1r4pt0r)

This time just a quick info. I just published library of KiCAD footprints that I made recently for my new project. The project itself has not been published yet and I want to keep it that way until I get first working prototype (what I hope will happen really soon). Meanwhile I am publishing this small library of footprints that I made for it with perspective of extending it in future with other hardware projects.

Still this is quite new topic for me as I have no electronics education, nor professional experience, so there is still a risk that I may fail at what I do and abandon such kind of projects. But for now, I just finished validation of footprints published here with a board that I ordered from JLCPCB, so you are guaranteed that they are fine (except one marked explicitly as such). Continue reading “My small library of KiCAD footprints” →

Creating one-file Linux distribution with docker

Posted on May 9, 2021 by Kamil (aka. v3l0c1r4pt0r)

Few months ago I wrote a tutorial about creating Linux distribution consisting of just busybox as its userspace. In the meantime I worked a bit with docker and it sounded like nice next step in learning docker to automate the process of creating Linux distribution using it. As a result, today I present Linux distribution built with docker and based on my previous tutorial. I called it busy-linux due to it consisting of only busybox at the moment. My plan is to develop it further, most likely for private purposes only, so there might not be much happening in the project, but for sure I want to create dynamically linked variant in the near future, as this is what my use case requires. In the meantime feel free to try it yourself. Continue reading “Creating one-file Linux distribution with docker” →