Stalwart is an open-source mail & collaboration server with JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV and WebDAV support and a wide range of modern features.
https://stalw.art/docs/install/platform/docker/
https://github.com/stalwartlabs/stalwart
Coriolis is Cloud Migration as a Service.
Migrating existing workloads between clouds is a necessity for a large number of use cases, especially for user moving from traditional virtualization technologies like VMware vSphere or Microsoft System Center VMM to Azure / AzureStack, OpenStack, Amazon AWS or Google Cloud. Furthermore, cloud to cloud migrations, like AWS to Azure are also a common requirement.
You can find further information about the project Coriolis at GitHub - https://github.com/cloudbase/coriolis
I often build Software-Defined Storage systems, which require robust hardware with both high performance and large capacity. I have recently found that Seagate has ultra-dense SAS-4 JBOD systems combining next-gen Mozaic drive readiness with energy-efficient design for AI, edge, and sovereign data infrastructure. It supports up to 3.2PB in a single 4 RU enclosure.
Here are few pictures ...
I’m trying to explain that an AI Factory truly functions like a factory, and that it is a fundamentally different discipline from a traditional datacenter.
A picture is worth a thousand words, just look at the photos below.
Voltage pushes current; resistance slows it down. But can we find something similarly elegant in IT infrastructure?
Computers and networks are more complex than a simple circuit. However, several concepts in networking, storage, and CPU performance behave similarly to Ohm’s law and can be modeled using comparable relationships. Below are practical, engineer-friendly analogies you can use when sizing, troubleshooting, or explaining systems.
Distinguished engineer Kelsey Hightower explores why understanding fundamentals matters more than chasing trends, sharing lessons from 25 years in tech at HAProxyConf.
Battery systems often rely on combining multiple cells, but how you connect them determines the final voltage, current, and capacity. Series and parallel wiring follow simple electrical rules, yet they lead to very different behavior under load. This brief post will walk through the core differences so you can understand the impact of each configuration.
In the video below, Robert Vojčík delivers an excellent talk about troubleshooting, “ghost hunting,” and the realization that the more we know, the more we understand how much we don’t know - a timeless truth that goes back to Socrates.
The presentation is in Slovak, but that shouldn’t be a problem, at least not in the present and future age of AI, when automatic English subtitles are just a few clicks away. And for those of us from the former Czechoslovakia, Slovak language feels natural anyway.
I need to rack and stack Cisco Nexus 93180yc FX3 in my datacenter, therefore, I need to know what airflow mode to choose.
The network ports should be located on the same side of the rack as the server’s rear panel, therefore, I need portside exhaust airflow mode.
Hope this helps other IT guys in the field.
Bellow is my cheat sheet about IPv4 addresses and sub-netting.
The cheat sheet is primarily for myself :-), but somebody else can find it helpful and use it.
Description: The math binary representation of IP octets (bytes) and relation to Net Subnetting.
Keywords: Class Addressing, Classless Addressing, Tips & Tricks
This is a very short blog post. Here is the procedure howto manually mount macOS shared folders into Ubuntu Linux running as VM in VMware Fusion ...
sudo vmhgfs-fuse .host:/ /mnt/hgfs -o allow_other
I have Dell PowerEdge R620 with iDRAC7 in my home lab and here is the home power consumption in two scenarios
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| Scenario 1: shutdown server still connected to power |
 |
| Scenario 2: server fully disconnected from the power |
The difference between above two scenarios is ~ 50W. Why?
Let's dive deeper.
One of my customers would like to backup FortiGate configuration as part of DRBC (Disaster Recovery and Business Continuity) Solution.
FortiGate supports REST API so it is great solution to periodically get configuration, store it into some file directory and leverage Veeam Backup and Replication solution to backup FortiGate configurations in with company standard protection process.
In this blog post I document all customer's specific design factors and also the solution prototype how to fulfill these factors and backup FortiGate configuration into file directory.
I personally prefer *nix way over Windows, therefore, I will leverage Linux Docker and PowerShell to get information from FortiGate security appliance and put it into file directory. Docker solution could be leveraged on Windows operating systems as well.
If you are interested in details, read on.
Design documentation is not literature; it is a technical tool. The goal is clarity, precision, and usability. Here are 11 rules to guide you when writing a design document.
Here is Greg Ferro’s approach to designing network design documentation. The “world” of networks is too big and varied to have only one document to cover more than one or two projects, but here are some rules to write a detailed Design document.
tmux is a terminal multiplexer. It lets you switch easily between several programs in one terminal, detach them (they keep running in the background) and reattach them to a different terminal. Tmux is available on Linux and BSD systems.
Let's dive into TMUX usage ...
ZeroEcho is an open-source cryptography toolkit for Java. It builds on trusted providers such as Bouncy Castle (especially for post-quantum algorithms) and organizes them into a coherent, safe, and scriptable framework.
It is designed for developers, researchers, and practitioners who want to build cryptographic workflows that are:
📂 Repository: https://gitea.egothor.org/Egothor/ZeroEcho
📖 Documentation: https://www.egothor.org/javadoc/zeroecho/lib/
sshuttle: where transparent proxy meets VPN meets ssh
https://sshuttle.readthedocs.io/en/stable/overview.html
GPON stands for Gigabit Passive Optical Network.
It’s a type of fiber-optic broadband technology used by internet service providers (ISPs) to deliver high-speed internet, TV, and phone services to homes and businesses.
Under EU law (eIDAS 910/2014), electronic signatures can be:
SES – Simple Electronic Signature (basic: typed name, click-to-sign, tickbox).
AdES – Advanced Electronic Signature (cryptographically bound to the signer, integrity-protected).
QES – Qualified Electronic Signature (requires a qualified certificate + secure signing device; legally equivalent to handwritten signature in the EU).
👉 Signi supports SES, AdES, and in certain cases QES (e.g. with BankID or qualified certificates).
Original Source: https://fohdeesha.com/docs/perc.html
This guide allows you to crossflash 12th gen Dell Mini Mono & full size cards to LSI IT firmware. Mini Mono refers to the small models that fit in the dedicated "storage slot" on Dell servers. Because iDRAC checks the PCI vendor values of cards in this slot before allowing the server to boot, the generic full-size PERC crossflashing guides do not apply. This guide however solves that issue. Technical explanation for those curious. The following cards are supported:
Hardware
E-Shop: https://dratek.cz/
Training videos:
Here is the process how to get Device ID and Local Key for Tuya device.
Pro převod souboru z MKV na MP4 pomocí ffmpeg použij následující příkaz:
ffmpeg -i vstup.mkv -codec copy vystup.mp4
Pokud MKV obsahuje kodeky, které nejsou kompatibilní s MP4 (např. některé titulky nebo audio kodeky), můžeš použít překódování:
ffmpeg -i vstup.mkv -c:v libx264 -c:a aac -strict experimental vystup.mp4
Because of sustainability, I would like to use old Laptop/Printer/Scanner devices.
This blog post is focused on Printer and Scanner.
I have a Canon MX350, so the runbooks for installing and using the printer and scanner were tested only with this model.
[SKIP - NOT USED] Install driver for NVIDIA Graphics Card
[SKIP - NOT USED] Configure the NVIDIA driver in a configuration file
[SKIP - NOT USED] NVIDIA configuration (it creates /etc/X11/xorg.conf)
Here is the Onliner to list VMs with custom attribute "Last Backup" ...
Get-VM | Select-Object Name, @{N='LastBackup';E={($_.CustomFields | Where-Object {$_.Key -match "Last Backup"}).Value}} | Where-Object {$_.LastBackup -ne $null -and $_.LastBackup -ne ""}
and here is the another one to count the number of such VMs ...
Get-VM | Select-Object Name, @{N='LastBackup';E={($_.CustomFields | Where-Object {$_.Key -match "Last Backup"}).Value}} | Where-Object {$_.LastBackup -ne $null -and $_.LastBackup -ne ""} | Measure-Object | Select-Object Count
How to get all VMs restarted by VMware vSphere HA? PowerCLI OneLiner below will do the magic ...
Get-VIEvent -MaxSamples 100000 -Start (Get-Date).AddDays(-1) -Type Warning | Where {$_.FullFormattedMessage -match "restarted"} | select CreatedTime,FullFormattedMessage | sort CreatedTime -Descending | Format-Table
I'm using Linux Mint with xsane for scanning documents on my old but still good Canon MX350 printer/scanner. Scans are saved as huge PDF documents (for example 50 MB) and I would like to compress it to consume much less disk space.
Install Ghostscript
apt install ghostscript
Compress the file input.pdf
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output_compressed.pdf input.pdf
Let's break down these options
Lossy compression (322x) from 50 MB to 155 KB without any visible degradation is worth to keep cloud (Google drive) costs low.
My preferred editor in unix-like systems is vi or vim. VI is everywhere and VIM is improved for scripting and coding.
You can do a native VCF SDDC Manager backup via SFTP protocol. SFTP is a file transfer protocol that operates over the SSH protocol. When using SFTP for VMware VCF's backup, you're effectively using the SSH protocol for transport.
For VCF older than 5.1, you have to allow ssh-rsa algorithm for host key and user authentication on your SSH Server.
It is configurable in SSH Daemon Configuration (/etc/ssh/sshd_config) on your backup server should have following lines to allow ssh-rsa algorithm for host key and user authentication.
How to use RaspberryPi inputs and outputs? The easiest way is to use the GPIO pins directly on the RaspberryPi board.
Raspberry Pi has 8 freely accessible GPIO ports. which can be controlled. In the following picture they are colored green.
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| GPIO ports |
Attention!!! GPIO are 3.3V and do not tolerate 5V !! Maximum current is 16mA !! It would be possible to use more of them by changing the configuration.
First you need to install the ligthhttpd (or apache ) server and PHP5:
sudo groupadd www-data
sudo apt-get install lighttpd
sudo apt-get install php5-cgi
sudo lighty-enable-mod fastcgi
sudo adduser pi www-data
sudo chown -R www-data:www-data /var/www
In the lighthttpd configuration
you need to add:
bin-path" => "/usr/bin/php5-cgi
socket" => "/tmp/php.socket"
Now you need to restart lighthttpd:
sudo /etc/init.d/lighttpd force-reload
This will run our webserver with PHP.
Now we get to the actual GPIO control. The ports can be used as input and output. Everything needs to be done as root.
First you need to make the port accessible:
echo "17" > /sys/class/gpio/export
Then we set whether it is an input (in) or output (out):
echo "out" > /sys/class/gpio/gpio17/direction
Set the value like this:
echo 1 > /sys/class/gpio/gpio17/valu
Read the status:
cat /sys/class/gpio/gpio17/value
This way we can control GPIO directly from the command line. If we use the www interface for control, we need to set the rights for all ports so that they can be controlled by a user other than root.
chmod 666 /sys/class/gpio/gpio17/value
chmod 666 /sys/class/gpio/gpio17/direction
"In this post I will show you how to create a template in XenOrchestra and using an image we created and customized ourself. " ... full blog post is available at https://blog.bufanda.de/how-to-create-a-template-on-xcp-ng-with-xenorchestra/
During the investigation of high disk response times in one VM using vSAN storage, I saw a strange vSAN metric (TCP Connection Half Open Drop Rate).
What is it?
Here are scrrenshot from Canonical webcast
Feature comparison
OpenStack technological stack
System containers (LXD) vs Application Containers (Docker)
Source: https://checkmk.com/
Search Engine for the Internet of Everything
Shodan is the world's first search engine for Internet-connected devices. Discover how Internet intelligence can help you make better decisions.
Network Monitoring Made Easy
Within 5 minutes of using Shodan Monitor you will see what you currently have connected to the Internet within your network range and be setup with real-time notifications when something unexpected shows up.
České Radiokomunikace (CRA) finišují s přípravami jednoho z nejambicióznějších projektů v oblasti digitální infrastruktury v České republice, nového datového centra. Podařil se další významný krok, CRA získaly územní rozhodnutí. V lokalitě Praha Zbraslav vznikne do dvou let jedno z největších zařízení svého druhu nejen v České republice, ale i v Evropě, které bude mít kapacitou přes 2 500 serverových racků a příkon 26 megawattů.
Source: https://blog.ja-ke.tech/2019/
This is a performance comparison of the the three most useful protocols for networks file shares on Linux with the latest software. I have run sequential and random benchmarks and tests with rsync. The main reason for this post is that i could not find a proper test that includes SSHFS.
Source: https://www.
JetKVM - Control any computer remotely by JetKVM — Kickstarter
https://www.cra.cz/cra-acquires-cloud4com-a-leading-cloud-computing-provider
A significant deal on the Czech IT scene, ARICOMA Group and České Radiokomunikace (CRA), the subsidiary of Cordiant Digital Infrastructure Limited (CORD), a specialist investor in digital infrastructure, announce that CRA are acquiring Cloud4com (C4C) from ARICOMA Group, along with its data centre in Lužice (together “the Transactions”). The price of the Transactions are partly conditional on 2024’s results, but expected to exceed CZK 1 billion. The Transactions, which took legal effect upon signature, also includes the conclusion of a strategic cooperation between ARICOMA Group and České Radiokomunikace.
PACKAGES
pkg install virtualbox-ose-additions
pkg install drm-kmod
/etc/rc.conf
ifconfig_em0="DHCP"
sshd_enable="YES"
ntpd_enable="YES"
ntpd_sync_on_start="YES"
moused_nondefault_enable="NO"
# Set dumpdev to "AUTO" to enable crash dumps, "NO" to disable
dumpdev="AUTO"
kld_list="/boot/modules/vboxvideo.ko"
zfs_enable="YES"
dbus_enable="YES"
moused_enable="YES"
devd_enable="YES"
vboxguest_enable="YES"
vboxservice_enable="YES"
tailscaled_enable="YES"
/boot/load.conf
drm_load="YES"
vboxdrv_load="YES"
vboxguest_load="YES"
vboxvideo_load="YES"
Source: https://www.packetstreams.net/2018/07/the-secrets-of-mtu-l2-mtu-vs-l3-mtu.html
Question: Is possible to emulate HDD serial number on VMware Workstation?
Answer ...
Yes, it is possible to emulate or specify a custom HDD serial number on VMware Workstation. You can do this by editing the virtual machine's configuration file (.vmx).
Lot of URLs have been changed after Broadcom acquisition of VMware. That's the reason I have started to document some of useful links for me.
A container-based approach to boot a full Android system on regular GNU/Linux systems running Wayland based desktop environments.
