Archive | Debian

How to compile ezstream from source

Debian Stretch’s version of ezstream is currently a bit out of date. Here is how you compile ezstream from source to get the latest improvements and bugfixes. Not even the INSTALL file in the ezstream repo has all the steps:

Note that the configuration file structure has changed from what can be found on older blog […]

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Boot your Raspberry Pi from nothing but an Ethernet cable

Zero Client: Boot kernel and root filesystem from network with a Raspberry Pi2 or Pi3

A Zero Client is a computer that has nothing on its permanent storage but a bootloader. Rather, it loads everything from the network. With the method presented in this article, you will be able to boot a Raspberry Pi into a full Debian OS with nothing more on the SD card other than the Raspberry firmware […]

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Gnome on Wayland on Raspberry Pi 2

Raspberry Pi2 and Pi3 running pure Debian 9 (“Stretch”) and the Linux Mainline/Vanilla Kernel

Update 2017 Feb 25: I have updated the step-by-step instructions based on the suggested fixes and improvements contained in the reader comments. I also have copied the step-by-step instructions from this blog post to the file hosted on From now on I will update the instructions only on github, so expect that the instructions in this […]

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How to convert images to PDF with paper and image size, without ImageMagick

ImageMagick’s convert tool is handy for converting a series of images into a PDF. Just for future reference, here is one method how you can achieve the same without convert. It is useful if you have 1-bit PBM images (e.g. scanned text) at hand:

This command concatenates all .pbm files, pipes the data to pnmtops to create an […]

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Digitizing books 
(International Dunhuang Project, CC BY-SA 3.0)

Digitize books: Searchable OCR PDF with text overlay from scanned or photographed books on Linux

Here is my method to digitize books. It is a tutorial about how to produce searchable, OCR (Optical Character Recognition) PDFs from a hardcopy book using free software tools on Linux distributions. You probably can find more convenient proprietary software, but that’s not the objective of this post. Important: I should not need to mention that depending […]

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'Hashed' brown potatoes. Hashing is important on more than just one level (picture by Jamie Davids, CC-BY-2.0)

Hashing passwords: SHA-512 can be stronger than bcrypt (by doing more rounds)

On a server, user passwords are usually stored in a cryptographically secure way, by running the plain passwords through a one-way hashing function and storing its output instead. A good hash function is irreversible. Leaving dictionary attacks aside and by using salts, the only way to find the original input/password which generated its hash, is to simply try all possible […]

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Unprivileged Unix Users vs. Untrusted Unix Users. How to harden your server security by confining shell users into a minimal jail

As a server administrator, I recently discovered a severe oversight of mine, one that was so big that I didn’t consciously see it for years. What can Unprivileged Unix Users do on your server? Any so-called “unprivileged Unix users” who have SSH access to a server (be it simply for the purpose of rsync’ing files) is not really “unprivileged” as the […]

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