Microsoft Teams on Fedora and Wayland with screenshare

Since the whole COVID19 pandemic hoax started a couple of months ago, working from home has become the new hip thing every company brags about on every social media known to humankind. The first step to be able to call yourself a proper COVID19 ready(tm) company is the ability to bother every employees with just a few mouse clicks. So here we are, with Microsoft Teams(tm) and a lot of other not very secure and massively bloated software elected as the center of the office life. …

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Kubernetes cluster for manufacturing engineering: tale of an epic commissioning

- Introduction A quite big company that produces parts for some of the most important automotive industry companies was interested in a cloud-based system to monitor the overall efficiency of their production machines, analyze some key parameters and optimize the production activities scheduling. Goal of the project was to connect eleven industrial manufacturing machines to the cloud, extract specific machine data and develop a web application for the visualization and management of such data, while guaranteeing information confidentiality and security. …

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Resize QCOW2 disk image

QCOW2 disk images can be easily grown using libvirt command line utils. Unfortunately it isn’t possible to grow QCOW2 images in-place or online. First of all, power off the virtual machine, grow the file and make a copy of it: $ qemu-img resize image.qcow2 +200G $ cp image.qcow2 image-new.qcow2 Identify the specific partion you intend to grow: $ virt-filesystems -a image.qcow2 -l Name Type VFS Label Size Parent /dev/sda1 filesystem ext4 - 536870912 - /dev/sda3 filesystem xfs - 45885612000 - Expand the actual partition: …

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Intel CPU, Hyper-Threading and Spectre STIBP mitigation

Yesterday I was reading phoronix 0 and phoronix 1 articles on STIBP mitigation impact on CPU performance, since I run a pretty old laptop equiped with a Sandy Bridge CPU I figured that I should do my own tests to see how bad things really are or aren’t. CPU: Intel Core i3-2310M - 2 cores / 4 threads Motherboard: Lenovo Thinkpad RAM: 2x4 GB DDR3 @1333 MHz HDD: Plextor M5pro OS: Fedora 29 x86_64 with stock kernels My benchmark of choice is compiling the Linux kernel (version 4. …

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Generate a secure GPG key

For some reason gpg gen-key still defaults to SHA1 and RSA2048, due to the known weaknesses of SHA1 it is probably a better idea to use SHA256. First of all, we need to create a configuration file. cat ~/.gnupg/gpg.conf" --- personal-digest-preferences SHA256 cert-digest-algo SHA256 default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 ZLIB BZIP2 ZIP Uncompressed To generate a new key type (also specify to use RSA 4096): gpg --gen-key ### or gpg --full-generate-key Other useful commands are: …

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AMD Ryzen on Linux

Finally we have some new hardware worth writing of and also spending money on. I have been using an AMD Ryzen 7 1700X based build for some time now and so far I am really liking it, the CPU is marvelous considering the pricetag and felt like a worthwhile upgrade from the Xeon E3-1241v3 I was using before; it is basically twice the cores clocked at pretty much the same speed. …

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Monitor hard disk health status with smartd on Linux

This does not really works, read this: https://uwot.eu/blog/monitor-hard-disk-smart-status-in-python/ First of all install smartmontools, it has the same name on pretty much every distro: $ emerge -a1 smartmontools Proceed to edit its configuration file, at the bottom of the file there is a quick explaination of all the available parameters: cat/etc/smartd.conf --- DEVICESCAN -H -R 1 -R 5 -R 7 -R 10 -R 11 -R 196 -R 197 -R 199 -R 200 -m user@domain. …

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Copy Linux sparse files over network

Sparse files are nice to use to store virtual machine’s virtual disks but can be a real pain in the ass to backup efficiently, especially over the network. Luckily rsync provides a way to intelligently copy sparse files both locally and over the network. The trick is use --sparse and --inplace options. Let’s say we have a sparse 60 GB qemu virtual disk with only around 7 GB used: $ ls -lh fedora24. …

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