Running Starnet2/Starnet++ with GPU on Linux

Remove stars from your astro pictures

StarNet ( has become the de-facto star reduction software of choice for astrophotography. Its purpose is to remove stars from the pictures, so you can focus on treating the background that require different settings than the stars. StarNet++ works pretty well on Linux (as a CLI application) but the executable does not support CUDA and GPU acceleration by default, making it a bit slow.

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My journey to astrophotography (part 1)

Astrophotography is an awesome passion that’s a mix of science, technology, history, art and dedication. I’m writing this post to share on my journey, not as a way to teach you anything about astronomy, but to offer a window in my life and also show that it’s possible to get started from zero in a new hobby, provided you invest some time into it.

Three years ago, I wrote a blog post on the reasons why I left my job and was pursuing something better suited to my mindset and where healing some wounds wound be possible. I removed it because a person I’d rather not have read it did (if you think it’s you, please return my calls). One or two years before, I started to notice that not only my job had eaten my hobby, but I was less and less interested in computer security and hacking in general – as doing 2 or 3 hours of hacking at home after having spent the day on a pentest was simply not something I enjoyed anymore. It was time for me to be passionate in something else that didn’t involve reading social media for hours (which is unfortunately one of my other hobbies). Maybe go back to something I always loved without taking the time to explore it, partially because I thought that was out of reach or because I should spend all my time trying to be the best hacker in the world (that didn’t work). A few people may know that I was using the handle “spacewalker” until the mid-2000, it didn’t come out of nowhere but from my fascination for the night sky and poor science-fiction cultural references.

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SSH: Best practices

The comments around the last OpenSSH issue (CVE 2016-0777, you must read excellent Qualys’ analysis if you’re interested with the details), I noticed that many people were not aware of some basic features of OpenSSH. I will attempt to give a few advises, prioritized in feasibility order, and with graphical annotations:

Very easy to set up.

Requires a lot of work to set up.

Will provide you some protections against difficult attacks.

Will protect against very simple or effective attacks.

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TrendMicro CTF 2015 : Poison Ivy (Defense 300) write-up

TrendMicro CTF logo

The challenge

This challenge was one of the 25 (minus a few canceled ones) written and organized by TrendMicro for their TMCTF 2015. I played with the Swiss team “On est pas contents” and I won’t disclose how badly we ranked 🙂 Some challenges were really boring (a crossword where half the solutions come from the commercial product aisle? Not for me). Some were frustrating, and one was really great: Poison Ivy network capture.

TrendMicro was very fast in shutting down the whole CTF website, so I can’t get an hand on the original challenge text. From memory:

A hacker was caught using Poison Ivy on a real system. Please understand what he was doing to get the flag. (ps: password is admin).

With that exciting information I start downloading the pcap. Opening in wireshark, it appears it’s a single TCP connection on the 443 port. This doesn’t look like https and the wireshark dissector doesn’t want to parse it. Right click on a packet, “Decode as…” and check “do not decode” makes us see the raw exchange.


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