Engineering notes since 2020

Michał Sobczak

Hands-on articles about Architecture, IT infrastructure, DevOps, Security, and AI/ML — tested on real hardware, written down so they can be reused.

Technology 103

  1. Technology1 min

    Frigate on ROCm in LXC container

    I thought that the best option to run Frigate is to run bare metal and skip virtualization and system containers. However now situation changed a little bit as I was able to fire up Frigate on LXC container on Proxmox with little help of AMD ROCm hardware assisted video decryption.

  2. Technology1 min

    PBS: decryption failed or bad record mac

    During sync between two Proxmox Backup Server instances I got “decryption failed or bad record mac” error message. So I decided to go for upgrading source PBS to match its version with target PBS. PBS upgrade To upgrade PBS: Get rid of bookworm sources.

  3. Technology1 min

    Resize TrueNAS drives

    Imaging you are running TrueNAS virtualized and would like to resize drive increasing its capacity. Then reboot and new size should be visible in ZFS pool. It has ability to auto expand by default.

  4. Technology1 min

    GitLab service desk with iRedMail: details

    In addition to my previous article about GitLab service desk feature with iRedMail I would like to enhance it a little bit my fixing some missing parts. Starting with connecting to PostgreSQL vmail database: Verifying mail server connectivity and TLS issues. GitLab (and iRedMail also) does not allow expired certificates.

  5. Technology3 min

    Hetzner Cloud with pfSense gateway

    Instead of using dedicated Hetzner servers you can use their cloud solutions for less demanding use case scenarios. The idea is to have one server for pfSense and the other one for regular private use, hidden behind gateway.

  6. Technology1 min

    Design and 3D-print wall switch in OpenSCAD

    So we decided to try Zigbee wall switches and many of available brands work with Fibaro. But not all of them and not in all configurations. Even if some switch or module works it may only work with Tuya gateway and application and not with Fibaro gateway.

  7. Technology1 min

    NextCloud 26 update failed

    I use NextCloud as alternative to Google Photos. My smartphone sends pictures over OpenVPN to my NextCloud instance. However for over a year Android application has been showing notification that server version is outdated, and from time to time automatic upload do not work.

  8. Technology2 min

    Maxed-out HP z800 RAM: 384 GB of DDR3

    In our lab we have 2 x HP z800 workstations. It is somehow ridiculous piece of hardware in terms of today standards. It’s got over 1 kW power supply, dual CPU motherboard and 12 memory slots.

  9. Technology1 min

    Sentry: broken transactions section

    Managing self-hosted Sentry is pretty straightforward. However due to high number of containers which Sentry is comprised of, there is high chance that we can encounter some kind of issues due to obvious nature of software development products which consists by definition some flaws.

  10. Technology1 min

    CentOS 7.9.2009 repository configuration

    As for year 2025 there is no more updates for CentOS 7.9.2009. Moreover you need to adjust repository file as network locations changed a little bit. So edit /etc/yum.repos.d/CentOS-Base.repo as follows: Then recreate yum cache: And if necessary: Now you are good to go with packages installation.

  11. Technology1 min

    RPCEnvironment init request failed

    I thought of adding another Proxmox node to the cluster. Instead of having PBS on separate physical box I wanted to have it virtualized, same as on any other environment I setup. So I installed fresh copy of the same Proxmox VE version and tried to join the cluster.

  12. Technology1 min

    IP2Location – complete IPv4 ranges ingestion

    IP2Location is a IP address databases where you can find the latest IP to location associations. The complete IPv4 range is 4 294 967 296 addresses which is 32 bit. IP2Location contains 4 291 944 710 addresses which is a little less.

  13. Technology4 min

    Cassandra performance tuning

    From 8k to 29k writes per second We took IP2Location version DB11 database. It holds few millions of IPv4 ranges which should unwrap onto over 2 billion addresses. Such number of entries is actually not a big deal for PostgreSQL RDBMS or Apache Cassandra distributed databases system.

  14. Technology8 min

    Casssandra: the introduction

    Distributed, partitioned, multi-master, increment horizontal scale-out NoSQL data manegement system for global mission-critical use cases handling petabyte sized datasets Dynamo, Amazon, Facebook, Apache… “Reliability at massive scale is one of the biggest challenges we face at Amazon“ source: “Dynamo: amazon’s highly available key-value store” In 2004 there have been…

  15. Technology3 min

    PostgreSQL manual partitioning

    Have you ever wondered how many tables can we create and use in PostgreSQL database server? Shall we call them partitions or shards? Why not to use built-in “automatic” partitioning? Partitions or shards? Lets first define the difference between partitions and shards.

  16. Technology1 min

    How to build computer inside computer?

    Even wondered how computer is built? And no, I’m not talking about unscrewing your laptop… but exactly how the things happen inside the CPU. If so, then check out TINA from Texas Instruments and open my custom-made all-in-one computer. I spend few weeks preparing this schematic.

  17. Technology2 min

    Big-tech cloud vs competitors: price-wise

    Imagine you would like run 2 x vCPU and 4 GB RAM virtual machine. Which service provider do you choose? Azure, AWS or Hetzner? With AWS you pay 65 USD (c5.large instance… and by the way why this is called large at all?).

  18. Technology1 min

    Who’s got the biggest load average?

    Ever wondered what can be the highest load average on the unix-like system? Do we even know what this parameter tells about? It shows the average number of either actively running or waiting processes.

  19. Technology1 min

    1000 Docker containers in Swarm mode

    I defined Docker Swarm cluster with 20 nodes and created service using Nginx HTTP server Docker image. I scaled it to 1000 container instances, which took a while on my demo hardware.

  20. Technology6 min

    Enterprise Architecture: modelling ArchiMate with Archi

    The article explores the use of ArchiMate, a modeling language, for enterprise architecture, focusing on its application through the Archi tool. ArchiMate offers a structured approach to modeling complex IT systems by providing various layers such as motivation, strategy, business, and technology.

  21. Technology1 min

    Recovering Sentry from disk full state

    If you have Sentry on-premise installed and run out of space, then bringing it back can be a little bit tricky. Especially if you have tons of projects configured with loads of data coming into it.

  22. Technology2 min

    E-mail Service Desk with self-hosted GitLab EE and iRedMail

    In order to process incoming e-mail messages as issues registered in GitLab you need to have catch-all mailbox and GitLab configured to handle it. However, there are few quirks you need to know when setting it up. Assuming you have GitLab installed as well as iRedMail.

  23. Technology4 min

    BPMN process modeling with Bonita Studio

    Building applications to do things better leads to operational excellence. And using digital tools and applications across the enterprise to do business differently – to enable innovation and creativity – leads to strategic advantage.

  24. Technology1 min

    Nested virtualization on Proxmox 7.4

    If you would like to run virtual machine inside another virtual machine, then you need to have CPU with nested virtualization feature and this feature needs to be enabled.

  25. Technology1 min

    Configure outgoing mail on Redash

    Installing Redash is straightforward if you use https://github.com/getredash/setup repository. Just run setup script to download, install and configure all required packages. But there is one thing missing from the default. It is mail configuration.

  26. Technology1 min

    Proxmox LXC backup with exit code 11

    In case you have some LXC containers on your Proxmox server, then there is high chance that you will get some errors during backup them up. Some container templates may not support snapshot or suspend modes. Instead you should you use stop mode.

  27. Technology1 min

    Proxmox 8 on Scaleway

    Bare metal servers offered at Scaleway are at reasonable prices, which can be compared to those on Hetzner. You even get Proxmox installation by default contrary to Hetzner were you need to install Debian first.

  28. Technology1 min

    Almost private-only Proxmox cluster

    If you wonder if it is possible to have private-only Proxmox cluster in Hetnzer, then the answer is yes, almost. Of couse you can order dedicated hardware to hide your boxes from public eyes, but if you are not going that way, then you can try other way.

  29. Technology1 min

    oc rsync takes down OKD master processes

    It might sound a little weird, but that’s the case. I was trying to setup NFS mount in OKD docker registry (from this tutorial). During oc rsync from inside docker-registry container I found that OKD master processes are down because of heath check thinking that there is some connectivity problem.

  30. Technology1 min

    Conditional Nginx logging

    Logging all HTTP traffic is often unnecessary. It especially applies to website which include not only text content but also all kind of additional components, like JavaScripts, stylesheets, images, fonts etc.

  31. Technology1 min

    Mounting SSD drive as swap in VM

    First of all this SSD drive which I use is somehow faulty. It is a Goodram SSDPR-CX400-01T-G2 drive of 1TB. It have been working fine for few weeks until some construction worker made a electric short causing some abnormal frequences in wires resulting a faulty drives and memory sticks.

  32. Technology2 min

    iRedMail mail server with SPF and DKIM

    Having your own mail server could be useful but also sometimes dangereous. I am happy to see appliance such as iRedMail which cover variaty of topics regarding a somehow complete solution. I pick Ubuntu 22 on Hetzner.

  33. Technology1 min

    Install Redash

    Data is valuable if consumed or at least identified. For private and corporate usages I suggest installing Redash as it gives options for saving queries, exporting data, creating visualizations and dashboards and also setting up alerts.

  34. Technology1 min

    WebGL performance

    As already stated in my year 2023 plans, there will be some time for graphics programming. Back in the days I was exploring OpenGL but that was way long ago. Nowadays I think to try something much simpler and accessible like for instance WebGL.

  35. Technology1 min

    Plans for 2023

    I’m looking forward for new year’s technology opportunities. I have few ongoing projects which I would like to finish by the end of this year.

  36. Technology1 min

    pg gem on Ubuntu 22

    I thought that installing pg gem on my clean Ubuntu 22 will be easy, but no. I got some weird message: So I tried to force installation: After this: On this Ubuntu 22 release installing Ruby interpreter from packages you got 3.0.2p107.

  37. Technology1 min

    SMB shares on Ubuntu 22 server

    SMB shares can be created either with UI on a desktop version or command line on a server installation. You can use this shares both on Linux stations and Windows boxes as well. We are going to create editors group and add current user to this group.

  38. Technology1 min

    simpleproxy

    In case you use ever changing outbound public IP connection like in Microsoft Azure, then you can try create machine with public IP and passing your local traffic to remote site via simplaproxy. L switch is for local and R is for remote.

  39. Technology1 min

    OpenShift 4.11 TLS handshake timeout on oc login

    Finally after OKD 3.11 support has ended I’ve decided to try 4.x releases. I found that there is quite nice installation assistant available on console.redhat.com (Red Hat Hybrid Cloud Console). So I tried it and installed new cluster on my dedicated hardware.

  40. Technology1 min

    Proxmox Backup Server timeout on disk initialization

    I installed Proxmox Backup Server several times, both on bare metal and virtualized inside Proxmox VE. This time I did it in PVE as virtual machine and encountered an issue while initializing disk with GPT, creating directory, LVM or ZFS.

  41. Technology5 min

    Proxmox VE & pfSense on Hetzner dedicated servers

    There is not too much a precise documentation from Hetzner available if you want to know what exactly you should do to run dedicated servers with primary and secondary public IP, virtual machines and vSwitch. There are some articles but they are written in non-informative way.

  42. Technology1 min

    OKD Docker private Registry on NFS mount

    If you use OKD/OpenShift then most probably you also run internal and private Docker registry for your builds. Cluster uses this to lookup for containers images for further deployment. For basic, default installation your Docker Registry is located in a project called default.

  43. Technology2 min

    Redeploying OKD 3.11 certificates

    Since the beginning of 3.x line of OpenShift/OKD releases there are various issues with internal certificates. TLS communication inside the cluster is used in several places like router, registry, compute nodes, master nodes, etcd and so on.

  44. Technology1 min

    Elasticsearch fix read only index

    In case you have been low on disk space on your Elasticsearch instance, there is high probability that your indices are marked read only now. In order to fix this one, first either delete/archive indices or increase your disk space.

  45. Technology1 min

    Reinstalling GRUB

    In one of my previous posts I mentioned some troubles regarding reinstalling Ubuntu 22, loosing ability to select OS and to boot at all actually. I found that Ubuntu 20 recognizes properly my fresh Windows installation but Ubuntu 22 does not.

  46. Technology1 min

    Expand CentOS LVM disk and filesystem

    There are two ways of expanding your root filesystem space. It’s either by adding additional volumes or by resizing PV. Let’s try the latter. We have CentOS 7 wth XFS running on Proxmox. First expand drive size with admin UI.

  47. Technology1 min

    Windows/Ubuntu dual boot issues

    I have dual boot on my Lenovo Thinkpad T420s, Windows 10 and Ubuntu 22. Actually I had, because I tried to reinstall Ubuntu 22 and I’ve lost my dual boot and ability to boot at all.

  48. Technology1 min

    Proxmox node out of cluster

    I was replacing drives and memory in one of servers and out of a sudden node was unable to start. When finally it booted it was gone out of cluster. Weird. This node has been installed on SSD drive which had 2 years or constant runtime.

  49. Technology1 min

    Ubuntu resize LVM

    During installation Ubuntu will create LVM with half of the space available. In order to expand it to whole space available you need to extend logical volume and expand file system as…

  50. Technology3 min

    Geo location with Filebeat on Elasticsearch 7, HAProxy and NGINX

    Display geo location map for NGINX traffic logs in Kibana Summary There are 3 things to remember and configure in order to have geo location map working: Use “forwardfor” option on pfSense HAProxy TLS frontend Enable filebeat NGINX module and point particular log files Define custom NGINX log format…

  51. Technology20 min

    Data Mining & Exploration

    Among 3 million public IP address ranges for the whole world, 68k belongs to the Russian Federation. This translates into 45 million addresses. Scanning the HTTP port on this population took 20 hours. I obtained 630k IP addresses with listening on port 80.

  52. Technology4 min

    Semiconductors

    The basis for the construction of diodes and transistors A semiconductor is a material whose electrical conductivity is between the conductors and insulators. Their resistance and conductivity depends on temperature and admixtures. [W] The most commercially used semiconductors are those based on silicon, and in the past also on germanium.

  53. Technology1 min

    Coil

    Energy in a magnetic field [209] Just as a capacitor works by storing energy as an electric field, an inductor stores energy as a magnetic field. The energy stored in the coil is calculated in terms of current.

  54. Technology1 min

    WordPress quirks and features

    I will start with the werid experience with one of WP themes – Polite and Polite Grid. I was wondering why my website make double requests on every page. One for the document and other for content. This was annoying as I was unable to measure traffic properly.

  55. Technology1 min

    Voltage divider

    Lowering the voltage value [202] The next example I want to present in practice is a popular voltage divider. It allows the output voltage to be reduced to the desired value due to the properties described a little earlier.

  56. Technology1 min

    Kirchhoff’s law

    Theory and practice [W] One of the basic principles of current flow is the first law of Kirchhoff, which says that for the electric circuit node, the algebraic sum of flow rates is zero.

  57. Technology2 min

    Capacitor

    Signal filtering [202] Capacitors are divided into polarized and non-polarized depending on whether the direction of their inclusion in the circuit is important. Generally speaking, capacitors filter the waveform of the power source.

  58. Technology1 min

    growfs fsck required (pfSense)

    In case you’ve managed to overcome other issues with system unable to boot, disk size not updated then there might be still one problem left. Sometimes resizing with gpart works fine but file system resize does not.

  59. Technology1 min

    WordPress migration

    After 2 years on DigitalOcean I’ve decided to move out. Not because it’s bad or expensive, but because I need one more feature which is IDS/IPS. By default WordPress installation on DO contains fail2ban, which is fine, but I find Suricata way more powerful.

  60. Technology1 min

    Proxmox setting locale failed

    If you log in to Proxmox’s shell and see error stating that “setting locale failed“, then execute the following command to get rid of that message: Not quite sure why it happens, but I see it almost all the time.

  61. Technology1 min

    Ruby on Rails vs PostgreSQL 14 partitioning primary keys

    Starting from PostgreSQL 10 we have available new type of paritioning, which is declarative one. Before we had inheritance which is also good but has some limitations. Now, with declarative partitioning user need not to specify partition name while inserting data.

  62. Technology1 min

    Multiple ZFS pools on single drive

    Image a hypothetical scenario having two 512 GB drives and want to use a Proxmox ZFS VM replication onto a second server with one 1 TB drive. Solution is quite simple.

  63. Technology1 min

    disk/partition ‘/dev/sdX’ has a holder (500)

    Having LVM on the disk causes system to automatically active such volumes. I installed used drive with Ubuntu on it to my Proxmox server. Using Proxmox’s UI you will not be able to wipe this drive, because volume group has been already auto-activated.

  64. Technology1 min

    Package is in a very bad inconsistent state

    Aborting Ubuntu packages update via Ansible gave me some weird state of libatk-wrapper-java-jni package. My playbook installs default-jre and it was painfully slow so I thought that there is some lockup, but there was not.

  65. Technology1 min

    UnsupportedClassVersionError

    Changing Java language level to run compiled code on older runtimes I’m working on some Java project. I use IntelliJ IDEA and deciced to go with Oracle’s OpenJDK-18. But… this runtime is available by default only during compilation in the IDE. In the system I have OpenJDK-11.

  66. Technology1 min

    min.io server behind NGINX reverse-proxy

    The most recent min.io server release requires one additional thing in the configuration comparing to versions in the past years. Having min.io on one box and NGINX on another one requires setting up a reverse proxy, which is straightforward operation.

  67. Technology1 min

    PostgreSQL 14, btree_gin no such file

    In case you would like to enable some PostgreSQL extensions there is basically one thing you should do which is install postgresql14-contrib package and then fire CREATE EXTENSION from PostgreSQL itself.

  68. Technology1 min

    DEGRADED ZFS pool, hard disk failure

    I own a preowned HP z800 workstation. As purchased it contained HDD inside – Western Digital WD5000AAKX-75U6AA0, SATA III, 500GB, 7200 RPM, 16MB of cache. Unfortunately it passes SMART and do not show wearout metric.

  69. Technology1 min

    Docker Registry on Ubuntu 20.04

    Docker Registry could be useful in various scenarios, but the most common would be containers orchestration software such as Kubernetes, OpenShift/OKD or Nomad.

  70. Technology1 min

    Ubuntu 21 (impish) updates unavailable

    I was trying to add some new packages and figured it out that my Ubuntu 21 is out of date. Unfortunately some time ago I unchecked all repositories in Software & Updates so my /etc/apt/sources.list was empty.

  71. Technology1 min

    Mirror Git repository

    If you need to mirror remote repository and push it to another remote repo, then there is one thing you should do to be able to export all remote branches and not only the master.

  72. Technology1 min

    Extending CentOS7 partition on Azure

    Using CentOS7 templates on Azure could result in lack of LVM, swap and non auto-extendable partitions. Some other templates have such feature, but not all of them. In case you assigned bigger disk in Azure portal you need still to do few things.

  73. Technology1 min

    Zabbix Proxy 4.2 installation years later

    Old Zabbix Proxy 4.2 installation could be quite confusing as you cannot grab the latest one to work with old Zabbix server. Fortunately there is archive packages repository at repo.zabbix.com/zabbix/4.2/ubuntu/pool/main/z/zabbix/. You need to keep track which operating systemu should be used.

  74. Technology1 min

    Installing PostgreSQL 14 on CentOS 7

    PostgreSQL 14 has few improvements over previous versions, especially older ones, like 9.6. This includes automatic data direction using partitioning. So, let’s install it on CentOS 7. Then you should login to the database and set password: Basic configuration includes firewall setup (if it’s active), access control and performance settings:

  75. Technology2 min

    Ohm’s law

    Theory and practice [204] This is the SI unit of resistance. 1 ohm is the electrical resistance between two points on a conductor when a constant potential difference of one volt between the two points causes a current of one ampere in the conductor.

  76. Technology1 min

    Circuit simulation

    Construction and testing of circuits in the TINA TI program To translate theory into practice, we can use the TINA package from DesignSoft for Texas Instruments. It is a tool for building virtual analog and digital circuits.

  77. Technology3 min

    Electric voltage

    Measure of the strength of electric charges. Electrostatic potential difference. Electronics is based on physics. The basic concepts here are voltage, current and resistance. We should start with that. The voltage is therefore a measure of the strength of electric charges.

  78. Technology1 min

    Recovering Elasticsearch 7 after power outage

    In case you encounted power outage or just blindly pressed restart button on your machine, there is high chance you will have some issues with your cluster. Mine has only one node, so there is no redundancy. If I lose indices then data is gone.

  79. Technology1 min

    Install qemu-guest-agent with Ansible on Proxmox 7.2

    I already have over 10 virtual machines in my home virtual environment. It is the number I find enough to start using some automation tools like Ansible. Installing Ansible on Ubuntu or CentOS systems is straightforward, just use regular apt or yum commands.

  80. Technology1 min

    Trapping ctrl+c in Bash scripts

    If you happen to have some Bash scripts and would like to abort it in clean way there is way to do it. You need to trap ctrl+c command. In case you have some while loop in your scripts, without it, pressing any abort commands is only half way effective.

  81. Technology1 min

    Elasticsearch 7: Could not locate that index-pattern

    Recently I’ve been tryout Elasticsearch 7 with Kibana and Metricbeat as well as Filebeat. I encountered some issues with indices so I dropped dashboards and visualizations and tried to load them again. I also cleared indices and patterns thru index management page.

Security 20

  1. Security5 min

    Make Opera browser great again!

    Get rid of ads and stop sending your data for free to Opera Little history My favourite browser was Opera for so many years. Between 2000 and 2005 it was adware showing, well… ads. In 2005 ads have been remove as the financing came from Google, Opera’s default search engine.

  2. Security2 min

    Recovering Proxmox VM from failed HDD

    Due to previous failure of SSD drive from Goodram I was forced to use brand new 1TB HDD from Toshiba. It was not a problem because the system running on it mainly have been using writes with not too much reads.

  3. Security1 min

    Germany BSI abuse message prevention

    In case of an Abuse message from BSI (in Germany), the following services must be enabled and disabled: Verify in 2 ways: Cutting with DROP traffic by Suricata IPS is not sufficient, because not all possible traffic signatures on port 111 are used and in most cases this port…

  4. Security1 min

    Dual WAN with failover in pfSense

    Once in a while there is outage in my main internet connection. In order to keep everything up and running (fortunately) we can setup secondary WAN over LTE connection. Start with connecting your device (e.g. LTE router) over ethernet cable to pfSense box.

  5. Security2 min

    Compatibility of Suricata IPS on Proxmox

    For non-users of either Proxmox or Suricata: the first one is virtualization appliance which helps firing up virtual machines as well as LXC containers and the latter is network traffic security system which is able to identify (IDS mode) or even block malicious traffic (IPS mode).

  6. Security2 min

    DNS privacy issues

    Until recently I though that having DNS subdomain entries provides enough obscurity thus should it be secure. If your DNS server does not offer transfering domain to another place then any subdomains should be hidden from public sight.

  7. Security1 min

    MikroTik basic reconfiguration

    In case you have access to MikroTik device without UI available, only CLI then you possibly would like to know how to do some basic reconfiguration to gain access to admin panel listening on local network. So… to change user password: To see all the configuration: To create PPTP VPN:

  8. Security1 min

    KeeneticOS basic reconfiguration

    In case you would like to have PPTP VPN server but no such is installed. But first things first. For such an obsolete hardware and software keep in mind that accessing it requires passing old host key algorithms and cipers.

  9. Security1 min

    Cowrie Honeypot

    Until recently I did not know that honeypots I encounter are based on Cowrie. But it does not change much to be honest. I already seen almost 100 of these while randomly exploring things on the internet. It was first thought that they are honeypots, by pure intuition.

  10. Security1 min

    SSH access using Ruby to outdated servers

    If for some unknown reasons you need to connect thru SSH to some outdated server using Ruby code, then you are in the right place. But first a little piece of theory behind it. There are 4 configurable things in OpenSSH concerning security configuration: KexAlgorithms: per-connection keys (key exchange) HostkeyAlgorithms:

  11. Security1 min

    KeeneticOS PPTP VPN server

    If you own this router then you might be interested how to setup VPN Server. I am personally interested in a way of how to do this using CLI only. It looks easy however there is one odd settings you should be aware of.

  12. Security1 min

    PPTP VPN on Wive-NG router

    On Wive-NG router when talking about VPN you have either PPP or WireGuard. As PPP is first listed so I tried it before trying WireGuard. Here are my thoughts. Configuration is pretty simple. In the router menu, go to Services – VPN Server. Then select PPTP protocol.

  13. Security1 min

    EcoRouter 2008 change user password

    Possibility that you own or operate EcoRouter 2008 with EcoBNGOS are very low. However just in case you will have to work with this one it will be useful to know at least some basic commands.

  14. Security1 min

    MikroTik RouterOS 7.5 change default DNS

    Want to change default DNS for the network in MikroTik’s RouterOS CLI? You can use web UI but it could have some issues preventing from configuration save, so it is nice to know how to use it via CLI.

  15. Security2 min

    airodump-ng and aireplay-ng to deauthenticate clients from access point

    Disconnecting wireless clients from access points The problem The nature of wireless networking is quite problematic because transmission goes over air and can be intercepted by anyone. Of course there is data packet stream encryption. But deauthentication frames are not encrypted and can be forged.

  16. Security5 min

    Suricata IDS/IPS on pfSense

    Detecting and preventing threats Introduction To provide security in a network you can deploy IDS or IPS systems. The difference is on the second letter, D stands for detection and P for prevention.

Publications 6

  1. Publications1 minPL

    OpenCL

    Programowanie CPU i GPU “Mamy rok 2022. Minęła ponad dekada od pojawienia się OpenCL. Omówię standard, przykładowy sprzęt, a także zaprezentuję rzeczywiste przykłady, które można wykorzystywać obecnie zarówno na historycznym jak i najnowszym sprzęcie, co ma pokazać swego rodzaju uniwersalność tego rozwiązania. Przy okazji zobaczymy jak ewoluowała technologia na przestrzeni ostatnich lat i czy teoria odpowiada praktyce.

  2. Publications1 minPL

    Simple High Performance Computing

    Podstawy elektroniki i budowa komputera w symulatorze “Jest to pierwsza część serii Simple High Performance Computing o tytule Podstawy elektroniki i budowa komputera w symulatorze. Swoim zakresem obejmuje zagadnienia związane z elektroniką, a konkretnie jej podstawami, począwszy od pierwotnych zasad fizyki przekładających się na komponenty elektroniczne, z których można budować złożone układy, a finalnie najprostszą obliczeniową maszynę cyfrową.

  3. Publications1 minPL

    Poradnik dla miłośników roślin – to nie jest takie trudne

    “Był początek lat dziewięćdziesiątych, kiedy przed moim mężem pojawiła się szansa otrzymania działki pracowniczej. Co prawda na razie było to wysypisko śmieci na obrzeżach istniejącego kilkanaście lat Ogrodu. Czekała nas przeogromna praca. Nasze dzieci mówiły na ten kawałek ziemi „Kambodża”. Musieliśmy wywieźć sterty śmieci, złomu i szkła…” – Ridero. 2019 (ISBN 9788381893862).

  4. Publications1 minPL

    Ruby on Rails – ćwiczenia

    “Dzięki książce “Ruby on Rails. Ćwiczenia” opanujesz podstawy tworzenia aplikacji internetowych za pomocą tej technologii. Nauczysz się programować w języku Ruby: poznasz jego elementy i zasady projektowania obiektowego, metody przetwarzania danych tekstowych, pracy z plikami i katalogami oraz obsługi błędów i wyjątków.

  5. Publications1 minPL

    Jakość oprogramowania. Podręcznik dla profesjonalistów

    “Czym jest jakość oprogramowania? Czy to wyłącznie miara technicznej doskonałości kodu? A może jakość to coś znacznie więcej? Czy niezawodne działanie i brak błędów świadczą o wysokiej jakości programu? Co charakteryzuje kod, który można uznać za dobry? Jak mierzy się jakość w projektach informatycznych?

  6. Publications1 minPL

    Programowanie w języku Ruby. Mikrousługi i konteneryzacja

    “Ruby to nowoczesny, wieloparadygmatowy, interpretowany język programowania. Wraz z platformą Rails stanowi jedno z najpopularniejszych rozwiązań służących do szybkiego tworzenia aplikacji sieciowych; wspiera wiele znanych serwisów dostępnych w internecie.

AI/ML 35

  1. AI/ML1 min

    LLM training parameters explanation

    Quick overview of LLM MLX LORA training parameters. weight_decay A regularization technique that adds a small penalty to the weights during training to prevent them from growing too large, helping to reduce overfitting.

  2. AI/ML4 min

    Train LLM on Mac Studio using MLX framework

    I have done over 500 training sessions using Qwen2.5, Qwen3, Gemma and plenty other LLM publicly available to inject domain specific knowledge into the model’s low rank adapters (LORA). However, instead of giving you tons of unimportant facts I will just stick to the most important things.

  3. AI/ML1 min

    YOLOx ONNX models use in Frigate

    YOLOX is an anchor-free version of YOLO, with a simpler design but better performance! It aims to bridge the gap between research and industrial communities. For more details, please refer to our report on Arxiv. https://yolox.readthedocs.io/en/latest/demo/onnx_readme.html https://github.com/Megvii-BaseDetection/YOLOX/tree/main/demo/ONNXRuntime To configure this in Frigate:

  4. AI/ML2 min

    Generating AI video with FramePack

    Upload image, enter text prompt and press Start Generation. It is as easy as it looks like. So we take some pre-trained models, feed it with some text prompt and starting image and things happen on GPU side to generate frame by frame and merge it into motion picture.

  5. AI/ML1 min

    GPU pass-thru in Proxmox 7 and Ubuntu 20, follow-up

    In previous article about GPU pass-thru which can found here, I described how to setup things mostly from Proxmox perspective. However from VM perspective I would like to make a little follow-up, just to make things clear about it.

  6. AI/ML1 min

    Configuring NVIDIA RTX A6000 ADA in Ubuntu 22

    I thought that installing NVIDIA RTX A6000 ADA in default Ubuntu 22 server installation would be an easy one. However, installing drivers from the repository made no good. I verified if secure boot is enable and no it was disabled.

  7. AI/ML1 min

    Code generation and artifacts preview with WebUI and codegemma:7b

    Generate WebGL, Three.JS, HTML, CSS, JavaScript, no Python code, single page with rotating cube, ambient lighting. Load libraries from CDN. Let ambient lighting be as such cube edges are visible. add directional lighting also pointing at the cube. Scene needs to be navigable using arrow keys. Ensure browser compability.

  8. AI/ML1 min

    Single vs multiple GPU power load

    slight utlization drop when dealing with multi GPU setup TLDR Power usage and GPU utilization varies between single GPU models and multi GPU models. Deal with it.

  9. AI/ML1 min

    Run DeepSeek-R1:70b on CPU and RAM

    Utilize both CPU, RAM and GPU computational resources With Ollama you can use not only GPU but also CPU with regular RAM go run LLM models, like DeepSeek-R1:70b. Of course you need to have fast both CPU and RAM and have plenty of it.

  10. AI/ML2 min

    Ollama with Open WebUI on 2 x RTX 3060 12 GB

    Ollama with WebUI on 2 “powerful” GPUs feels like commercial GPTs online I thought that Exo would do the job and utilize both of my Lab servers. Unfortunately, it does not work on Linux/NVIDIA with my setup and following official documentation.

  11. AI/ML5 min

    Exo: the GPU cluster (tinygrad | MLX)

    Theory: running AI workload spreaded across various devices using pipeline parallel inference In theory Exo provides a way to run memory heavy AI/LLM models workload onto many different devices spreading memory and computations across.

  12. AI/ML2 min

    Qwen LLM

    What is Qwen? This is the organization of Qwen, which refers to the large language model family built by Alibaba Cloud. In this organization, we continuously release large language models (LLM), large multimodal models (LMM), and other AGI-related projects. Check them out and enjoy! What models do they provide?

  13. AI/ML1 min

    NVIDIA CC 7.0+: how to run Ollama/moondream:1.8b

    Well, in one of the previous articles I described how to invoke Ollama/moondream:1.8b using cURL, however I forgot to tell how to even run it in Docker container. So here you go: You can specify to run particular model in background (-d) or in foreground (without parameter -d).

  14. AI/ML3 min

    OpenVINO in AI computer vision object detection (Frigate + OpenVINO)

    What is OpenVINO? “Open-source software toolkit for optimizing and deploying deep learning models.” It is developed by Intel since 2018. It supports LLM, computer vision and generative AI. It runs on Windows, Linux and MacOS. As for Ubuntu, it is recommended to run on 22.04 LTS and higher.

  15. AI/ML1 min

    Invoke ollama/moondream:1.8b using cURL

    Given this image: You would like to describe it using Ollama and moondream:1.8b model you can try cURL. First encode image in base64: Then prepare request: And finally invoke cURL pointing at your Ollama server running: In response you could get somehing like this:

  16. AI/ML2 min

    AI video surveillance with DeepStack, Python and ZoneMinder

    For those using ZoneMinder and trying to figure out how to detect objects, there is deepquestai/deepstack AI model and builtin HTTP server. You can grab video frames by using ZoneMinder API or UI API: You need to specify address, monitor ID, user, password.

  17. AI/ML1 min

    Block AI web-scrapers from stealing your website content

    Did you know that you may block AI-related web-scrapers from downloading your whole websites and actually stealing your content. This way LLM models will need to have different data source for learning process! Why you may ask?

  18. AI/ML4 min

    BLOOM LLM: how to use?

    Asking BLOOM-560M “what is love?” it replies with “The woman who had my first kiss in my life had no idea that I was a man”. wtf?! Intro I’ve been into parallel computing since 2021, playing with OpenCL (you can read about it here), looking for maximizing devices capabilities.

  19. AI/ML3 min

    Microsoft Azure AI Services: computer vision

    Use Microsoft Azure AI Services to analyze images, voice, documents. No AI/ML or coding skills required. Responsible AI applies by EU AI act. Formerly Cognitive Services. Course of Action What is Microsoft Azure?

  20. AI/ML3 minPL

    Demaskowanie “możliwości” ChatGPT

    Wstęp Dzisiaj wyjątkowo będzie po polsku na temat ChatGPT. Zadałem sobie nieco trudu i wypróbowałem jego “możliwości” z zakresu programowania jako, że zasłyszałem o takiej opcji. Moim ulubionym w ostatnim czasie tematem jest OpenCL, zatem…. JA: to napisz mi kernel OpenCL który służy do sortowanie liczb zmiennoprzecinkowych Dostałem sortowanie bąbelkowe….

  21. AI/ML1 min

    Thoughts on GPU thermal issues

    I’ve been playing around with several devices in a context of running OpenCL code on them. They have one common thing which is excessive heat coming out of GPU and heatsink being unable to dissipate it. I start with MacBookPro3,1. It has NVIDIA 8600M GT, which is known to fail.

  22. AI/ML1 min

    Device performance in OpenCL DES

    Among various computing devices I have there is one that stands out it is NVIDIA Quadro NVS 140M because it supports only FP32 (float) operations, but not FP64 (double). It is generally too old. In OpenCL we have both pow function which takes double and float parameters.

  23. AI/ML6 min

    GPU passthru in Proxmox for OpenCL, ufff

    You can put your #GPU in #Proxmox server box and pass thru computational power to virtual machines… just in case you would like to run your AI/ML things alongside your virtualized NAS 😀 Finally I got it working. I think so.

  24. AI/ML3 min

    Text processing in OpenCL

    OpenCL is excellent in the field of numbers, but not that much into text processing. It lacks even basic functions available in regular C99. So the question is if it is worth trying to process some text in it.

  25. AI/ML5 min

    DES cipher is 40 times faster in OpenCL

    OpenCL implementation od DES cipher is way faster than regular single-threaded C program. 1 mln encryptions take less than a second on RTX 3050 Ti, but also as much as almost 40 seconds on Intel i5-10200h single-thread application.

  26. AI/ML1 min

    Failed to load library libOpenCL.so.1

    Today I came back to my OpenCL project (can be found here). I have had not tried it on my fresh Ubuntu 22 installation on my Dell g15 with RTX 3050 Ti. Altough I’ve got NVIDIA driver metapackage installed my program reported that there is some problem with shared library:

Hobby 14

  1. Hobby1 min

    OpenHAB failing to grab RTSP snapshots

    If you have OpenHAB on Proxmox or any other virtualization and it sometimes fails to grab RTSP stream and create snapshots, then there is high chance that everything is fine with the camera and network and the problem is within your server hardware.

  2. Hobby1 min

    Video playback not working on LinkedIn in Opera on Ubuntu 22

    On fresh installation of Ubuntu 22, using Opera for video playback can be an issue. So even after installing all things that you may think it could help – it does not work. The solution is to install chromium-ffmpeg and copy its libffmpeg.so library into Opera installation folder.

  3. Hobby2 min

    Fibaro Home Center 3 vs OpenHAB

    Recently we’ve ordered Fibaro’s HC3 as a replacement for OpenHAB. First because it has integration with Satel alarm system and second that it has native Zigbee support next to default Zwave. OpenHAB also has support for Satel and by using external adapter you can connect Zigbee devices too.

  4. Hobby1 min

    Fixing Ubuntu 22 camera recording

    I tried to record video on my Dell G15 laptop using built-in camera. Unfortunately, by default it does not work. I tried Cheese and Webcamoid using several different settings. Cheese did not work with both built-in and external camera. Webcamoid worked with external camera only.

  5. Hobby1 min

    Turn on/off Samsung SmartThings A/C from Fibaro HC3

    In order to integrate your SmartThings devices into Fibaro HC3 you need to create access token and review API documention which can be found here: https://developer.smartthings.com/docs/api/public#tag/Devices/operation/getDevices Then, to send on or off command to your device, grab its UUID, create QuickApp with the following code:

  6. Hobby1 min

    Connecting WiZ LED lights to Fibaro HC3

    In popular DIY markets you can buy Philips WiZ LED light bulbs. They are affordable choice over Hue lights. WiZ lights operate thru WiFi connection and can be integrated easily within OpenHAB system as a wizlighting binding coming from marketplace.

  7. Hobby1 min

    Create own shorcut icon in Ubuntu 22 panel

    If you want to run some curl on icon click from Ubuntu 22 panel, then you need to create file in ~/.local/share/applications: Then after few seconds, press special key (aka Windows key) and type your “application” name.

  8. Hobby1 min

    chromium downloader for MacOS 10.8.5

    If you happen to have MacBookPro3,1 with Intel Core 2 Duo 2.2Hz DDR2 SDRAM with MacOS 10.8.5 on board then you probably wonder if there is a chance to access internet with modern browser. Yes, now you can with chromium downloader for chromium-legacy.

  9. Hobby1 min

    Bash controlled Raspberry Pi 3B relay hat

    If you would like to control some electrical devices by switching them on and off then one possiblity is to use Rasberry Pi relay hat. It is from Waveshare/Botland and it fits on top of your Raspberry Pi. It contains 3 relays controllers with screw connectors.

  10. Hobby1 min

    c++11 on MacOS 10.8.5 or even 10.4.11

    I tried to compile my c++ code with c++11 features on GCC 4.2.1 which is default on my MacBookPro3,1 with MacOS 10.8.5. I used random library, so I needed newer version of GCC, 4.7 at least to be more precise.

  11. Hobby1 min

    MacPorts installation on 10.8.5

    To bring and old MacBookPro up to date you can use MacPorts. First you should download and install MacPorts package from macports.org. There is a pkg file to use specifically for Mountain Lion. That’s the easy one. A little harder would be to grab working XCode with command line tools.

  12. Hobby1 min

    Apple MacBook Pro 15 inch (2007)

    I have this nice MacBook Pro (3,1) from 2007. It has Intel’s Core 2 Duo running 2.2 GHz. Unfortunately the battery is dead or electronics reponsible for charging it. It arrived fully charged and was working for like 2 hours or so.

  13. Hobby1 min

    (X)Ubuntu on ThinkPad T61

    Recently I got Lenovo ThinkPad T61 in working conditions. It has Intel Core 2 Duo T7100 @1.8 GHz, 4 GB of DDR2.

Photography 17

  1. Photography1 min

    How to import files into darktable

    If you try using darktable 3.6 and previously been using older versions then you may be confused. In lighttable, import pane there are two buttons instead of one. Below you can find a little explanation. 1.

  2. Photography1 min

    RAW processing with darktable 3.6

    If you shoot RAW then most probably you need to have dedicated software for processing such files. I use darktable, however it is worth to mention that Windows Explorer and built-in image viewer can display RAW image. Just in case there is no other software available at the moment.

  3. Photography1 min

    Nikon D7100 vs D200

    Some time ago I got rid of my D200. But now I have another one in excellent shape. In the past I upgrade from it to D7100 which is better in terms of resolution, sharpness and features.

  4. Photography2 min

    NIKON D7100, Yongnuo 50/1.8

    It is a 24 megapixels digital SR camera. Sadly to say that I do not use this maximum resolution, because files are just too big. I even skipped using NEF raw files they are just enourmously huge for me. You can choose between 6 MP, 16MP and 24MP.

  5. Photography1 min

    Adapting SMENA 8M lens to NIKON F

    As previously stated, I tried to adapt SMENA 8M 40mm, f/4.0 lens to some DSLR. After week with no camera at all today I got my almost brand new NIKON D70s with only 1k pictures taken.

  6. Photography1 min

    SMENA 8M 40mm, f/4.0 lens

    Continuing with USSR made SMENA 8M. I decided to take apart lens unit. It consist of upper cover with levers and lower unit with shutter blades, shutter spring-based mechanism and optics. There are three blades. They are mounted on pins located on the rotating plate.

  7. Photography3 min

    SMENA 8M, 35mm camera

    I got this one as an exchange item for some old LCD TV. It is 35mm film compact camera made in USSR. Having quite a big monopoly on the eastern market, Soviet Russia manufacturer brought over 30 million of these to the markets. SMENA 8M is a very lightweight camera.

  8. Photography1 min

    KIMUNOR 300mm f/5.6

    It seems to be very decent lens. Especially speaking of build quality which is glass and metal with very little rubber and plastic. It is prime lens at 300mm with constant f/5.6. It is quite light. Has 3 rings. First to adjust focus. Second to adjust aperture.

  9. Photography1 min

    COSMOS AUTO TELEPLUS 2x

    Made in Japan. This teleconverter fits on NIKON F cameras. It is a MF thing, however it has automatic aperture control as stated in its name “AUTO”. It increases focal length by the factor of 2. It came with a very elegant zipping pocket.

  10. Photography2 min

    NIKON D200

    I was looking for NIKON camera that will allow me to use manual focus lenses with proper light metering. I found that D200 would suite this need. It a 10 megapixels camera with SONY ICX-483-AQA sensor. It seems that is the only camera using this one.

  11. Photography5 min

    NIKON D70S

    This would be my favorite and the only one digital camera, except one thing. It does not meter light on AI lenses, unfortunately. My copy already shot almost 50 000 pictures. It shows no wear at all, including battery.

  12. Photography1 min

    NIKKOR 50 f/2

    This is one of my favorites. It is a NIKON F mount, AI lens with constant speed at f/2. It is a regular/normal lens. It has no AF, only MF. This copy come from between 1977 and 1979. It is clean inside. Focus and aperture ring operate very well.

  13. Photography2 min

    SOLIGOR 70-150 F/3.5 MC

    As always I bought it for next to nothing. It is NIKON F mount lens. To be more precise it it a AI lens. No AI-S features. This review will be a little shorter than usually, because the lens is crippled by malfunctioning aperture blades.

  14. Photography3 min

    VIVITAR 70-210 F/4.5 MC

    Together with NIKON 75-150 f/3.5 and SOLIGOR 70-150 f/3.5 I recently purchased this one, which is NIKON F mount VIVITAR 70-210 telephoto lens with constant f/4.5. My main criteria did not change, so it should be reasonably priced and built. I thought that this would be a good one.

  15. Photography2 min

    NIKON 35mm film MF/AF – camera/lens compatibility

    As many know, NIKON cameras and lenses have been heavily used by pros in the 1970-1980. They invest a lot in their gear. That is why the compatibility is important. You do not choose only a camera or lens, you choose complete system.

  16. Photography3 min

    NIKON 75-150 f/3.5, SERIES E

    Recently I have been looking for some old style NIKON F AI MF lenses across the internet. I got this one. It is a discount, costs next to nothing. Of course it’s not only about the money, but about the performance you can get from it.

Other 3

  1. Other1 min

    About me

    Hello. I’m Michael, I’m IT professional and enthusiast. I graduated computer programming as well as economics at Szkoła Główna Handlowa in Warsaw. I’m author of 5 books concerning software design, development, quality assurance and performance.