Testing J-Pilot feature-gtk3 branch

, 3 min read

J-Pilot 1.8 still relies on GTK+ 2, which is heading towards planned deprecation. The entire work to migrate to GTK+ 3 is done by volunteers, Judd Montgomery and David Malia. This post is about testing this new experimental branch feature-gtk3 from GitHub. Installing this branch is…

Analysis And Usage of SSHGuard

, 5 min read

To ban annoying ssh access to your Linux box you can use fail2ban. Or, alternatively, you can use SSHGuard. SSHGuard's installed size is 1.3 MB on Arch Linux. Its source code, including all C-files, headers, manuals, configuration, and makefiles is 8 KLines. In contrast, for fail2ban just the…

ssh as SOCKS server

, 1 min read

Assume three computers A, B, and C. A can connect to B via ssh, but A cannot connect to C, but B can connect to C. A -> B -> C On A open ssh as SOCKS-server with ssh -N -D 9020 user@B Now on A one can use brave --proxy-server="socks5://localhost:9020" The browser will then show…

Poisson Log-Normal Distributed Random Numbers

, 1 min read

Task at hand: Generate random numbers which follow a lognormal distribution, but this drawing is governed by a Poisson distribution. I.e., the Poisson distribution governs how many lognormal random values are drawn. Input to the program are $\lambda$ of the Poisson distribution, modal value and…

Performance comparison Ryzen vs. Intel vs. Bulldozer vs. ARM

, 2 min read

For comparing different machines I invert the Hilbert matrix $$ H = \left(\begin{array}{ccccc} 1 & {1\over2} & {1\over3} & \cdots & {1\over n} \\ {1\over2} & {1\over3} & {1\over4} & \cdots & {1\over n+1} \\ {1\over3} &…

dumpe2fs: When was my hard-drive first formatted?

, 3 min read

I repeatedly forget to remember when my hard-drive or SSD was first formatted. Command for this is dumpe2fs. This command is part of package e2fsprogs. Example: # dumpe2fs -h /dev/sda1 dumpe2fs 1.45.6 (20-Mar-2020) Filesystem volume name: <none> Last mounted on: /boot Filesystem…

Unitymedia und SIP VoIP

, 1 min read

Folgendes schrieb ich an die Firma Unitymedia, jetzt Vodafone: Ich möchte gerne meine Rufnummer XXX über meine YYY Telefonanlage via VoIP betreiben. Ich verwende den von Ihnen bereitgestellten Router "Vodafone Station". Meine Kundennummer lautet ZZZ. Ich benötige nun folgende sieben…

Compiling Java source to binary (native)

, 2 min read

With GraalVM you can now fully compile a Java file to a native binary. This is also called AOT, ahead-of-time compilation. Compilation is very slow, and resulting binary is huge as it must contain all code which might be referenced. In contrast the class file usually is quite small. Though, it is…

Windows 10 very slow after reboot

, 1 min read

I repeatedly noticed that my Microsoft Windows 10 laptop is noticeably slow when restarted. This time I rebooted the laptop and just watched what happened in task manager. Below are the results. Waiting for more than 10 minutes doing nothing: one third of the machine is loaded with managing its…

Online Dial-A-Ride

, 44 min read

window.MathJax = { tex: { tags: 'ams' } }; Introduction 1. Preliminaries 2. State of the art 3. Algorithms 3.1 Algorithm: ABORT 3.1.1 ABORT for open online Dial-a-Ride 3.1.2 ABORT for closed online Dial-a-Ride 3.2 Algorithm: ABORT-AND-WAIT (AAW) 3.2.1 AAW for closed online…

Statistics of this Blog: Crossed 110.000 Views

, 1 min read

This blog was viewed more than 110.000 times since its inception and had more than 84.500 visitors. The averages per month are: The most popular posts this year are: The most popular posts over all years are: Distribution of countries accessing this blog over last 365 days, USA is number one,…

Configure boot settings in UEFI

, 2 min read

Main source for trouble-shooting is Arch-Wiki UEFI. It describes the commands: bcfg within UEFI shell Linux command efibootmgr 1. It is ighly recommended to install the UEFI-shell, which is in package edk2-shell. On Asrock copy cp -p /usr/share/edk2-shell/x64/Shell_Full.efi /boot/shellx64.efi So…

SSD Speed on Dell XPS 13 9350 with Samsung EVO 970 Plus

, 1 min read

In continuation of blog-post SSD Speed on Dell XPS 13 9350, here are performance measurements for a Samsung EVO 970 Plus in Dell XPS 13. Caveat from Dell xps 13 9350 and Samsung 970 evo M.2 nvme Compatability?: However, be aware that although the XPS 13 9350 uses a PCIe x4 configuration for its…

Blocking IP addresses with ipset

, 2 min read

In Chinese Hackers I mentioned that I block ssh attackers with the help of fail2ban. Unfortunately, fail2ban uses iptables to create firewall rules in "Chain f2b-SSH" for each individual IP address. For a modern processor this is no problem, even if you have thousands of these rules.…

ASRock DeskMini A300M with AMD Ryzen 3400G

, 3 min read

Below are some photographs during assembly of the Asrock A300M with an AMD Ryzen 5 Pro 3400G processor. The Asrock website detailing the specs of the A300M: DeskMini A300 Series. Three noticable reviews on the A300M: Anandtech has a very readable review of the A300M: Home> Systems …

Reply to: Neural Network Back-Propagation Revisited with Ordinary Differential Equations

, 2 min read

This article is worth reading: Neural Network Back-Propagation Revisited with Ordinary Differential Equations I replied: Thank you very much for this very informative article providing many links, the Python code, and the results. According the mentioned paper from Owens + Filkin the speedup…

Calling C from Julia

, 1 min read

Two ways to compute the error function or Bessel function in Julia. 1. Calling C. On UNIX libm provides erf() and j0(). So calling them goes like this: ccall(("erf","libm.so.6"),Float64,(Float64,),0.1) ccall(("j0"),Float64,(Float64,),3) In this case one can omit the…

Gunnar Uldall's Tax Tariff

, 2 min read

Gunnar Uldall wrote a a book with title "Die Steuerwende" in 1996. 1. Proposal. In this book he proposed the following tariff, $x$ is in DEM. $$ t_u(x) = \begin{cases} 0 & \mbox{if } x\le12000 \\ 0.08\left(x-12000\right) & \mbox{if } 12001\le x\le20000 \\ …

Splitting and anti-merging vCard files

, 2 min read

Sometimes vCard files need to be split into smaller files, or the file needs to be protected against merging in another application. 1. Splitting. Below Perl script splits the input file into as many files as required. Output files are named adr1.vcf, adr2.vcf, etc. You can pass a command line…

Automated Rebooting of Auerswald Communication System

, 2 min read

The wired telephones in my house are connected to a telephone-system from Auerswald. It's Auerswald COMpact 5020 VoIP. This PBX handles VoIP and ISDN. My children make fun of me that I still use landlines, they just use cell phones. Unfortunately since a couple of months the system no longer is…