Setting up a v3 user on the server-side agent for the default Linux snmpd (net-snmp package). Out of scope: SNMP traps and read-write (rw) users.
SNMP version 3 allows packet transmission in encrypted form, making it safe to transfer telemetry over public networks without the risk of exposing either authentication information (analogous to a community string) or the data stream itself, which is encrypted using a symmetric algorithm with a shared key.
In the fast-paced world of software development, ensuring the quality and reliability of applications is crucial. With the ever-increasing complexity of software systems, it becomes essential to adopt a comprehensive and structured approach to testing. One such approach can be encapsulated in the acronym "RABBIT," where each letter stands for a distinct branch of testing. This multifaceted strategy covers various testing methodologies that together create a robust framework for quality assurance. This article explores each branch of RABBIT testing in detail, providing insights into their significance, implementation, and appropriate use cases.
Recently I have bought starfive visionfive-2 SoC for my own experiments, honestly speaking
I am striving to work with risc-v. After some time I decided to share my experience. Here my bulletpoints:
Small preparation USB-to-Serial connector Write image to microSD/SSD Set boot mode settings
Boot Update bootloader Build kernel Native build Pod build Cross-build on amd64: fast and handy
Chroot to risc-v system from amd64 and install packages
Bonus 1: run qemu with risc-v
Bonus 2: build deb packages for risc-v
Bonus 3: kernel build script
Conclusions
Hello my name is Dmitry. Recently I wrote article "Building firmware for Orange PI i96 (Orange PI 2g-iot) from scratch" . If you haven't read it yat, I highly recommend. And there I noticed that in order to build firware on current kernel, I have to rewrite drivers wirh new archetecture "Device tree". In this article I have revelate how I do it.
Hellow my name is Dmitry. Once I bought "Orange PI i96", but unfortunately producer not update it firmvere very long. Last firmwere kernel version is 3.10.62 but kernel current at time this article writing (russian version) is 6.5.1. And so I decide build my own firmware from scratch, and do it from sourse completely.
In this article, I will cover the memory consumption of .NET applications on Linux. Firstly, we will try to understand the idea of virtual memory. Then, we will examine the memory statistics that Linux provides, such as RSS (Resident Set Size), VmData, RES (Resident Memory Size), and SWAP. Following that, we will delve into specifics related to the .NET.
There are two articles on Russian, the author of which writes a virtual machine (interpreter) for executing a simple bytecode and then applies different optimizations to make this virtual machine faster. Besides that, there is a compiler of a simple C-like language into this bytecode. After reading this article and getting familiar with the compiler, I thought that it would be interesting to try writing a virtual machine for this language that would be able to apply JIT-compilation to this bytecode with the libjit library. This article describes the experience of doing that.
I found several articles online that describe the usage of this library, but those that I saw, describe the compilation of concrete programs with libjit, while I was interested in compiling arbitrary bytecode. For people interested in further reading, there is an official titorial, a series of articles and a series of comparisons (in Russian).
The implementation was done in C++ because we aren`t playing games here. All my code is in my repository. The "main" branch has just the interpreter of the PigletVM bytecode; "labels-with-fallbacks" has a partial JIT compilation implementation (that doesn`t support JUMP instructions), "full-jit" has fully working JIT-compilationl; "making-jit-code-faster" makes code generated by JIT work faster and "universal-base-vm*" branches merge the interpreter and JIT-compilation implementations, by implementing a base generalised executor, which can be used for different implementations of PigletVM (both the interpreter and libjit compilation)
When using older version of Java with not updated truststore, you may face an error while connecting to web hosts, that Java is unable to find a valid certification path to the requested target.
This happens because JRE truststore is unaware of the new root certificate that is being used by Let's Encrypt nowadays. Below I tried to clarify detail behind this issue and how to solve it. I hope newcomers might find this material helpful.
 ChatGPT was not used in writing this article. The animated image uses the webp file format instead of gif. |
In this article, you will find a complete description of how to make a Wi-Fi internet radio receiver from a router that can play mp3 streams from internet radio stations. It is also possible to switch between two internet radio stations. We will use OpenWRT firmware installed on the router to create a Wi-Fi internet radio. It is possible to complete this project without using a soldering iron. All the components can be placed inside the router to create a finished device — a Wi-Fi internet radio. |
Arbeiten im technischen Support brachte zusätzlich zu allen Aufgaben die Pflicht mit sich, die Kommunikationskanäle zu überwachen. Dies wurde über den Grafana-Dienst realisiert, der die erforderlichen Metriken aus Zabbix bezog. Da die Art der Arbeit jedoch bedeutete, dass man nicht immer an seinem Arbeitsplatz sitzt, kam mir die Idee, dies ein wenig zu automatisieren und Benachrichtigungen auf das Telefon oder zum Beispiel in einen Messenger zu erhalten, falls ein Kommunikationskanal ausfällt. Allerdings hatte ich keinen Zugriff auf das Zabbix-System und auch keinen erweiterten Zugriff auf Grafana.
gookit/goutil An extended library of Go's common functionality. Contains: number, string, slice/array, Map, struct, reflection, text, file, error, time and date, test, CLI, command run, system information, formatting, common information acquisition, etc.
How do people usually write a server if they don't really care about performance? A program starts, then starts accepting incoming connections from clients and starts a new thread for each client, which is engaged in servicing this client. If you use framework, like Spring or Flask or Poco there, then it does something like this inside itself - the only difference is the threads can be reused, that is, taken from a certain pool. It's all quite convenient, but not too effective (and Spring is bad). Most likely, your threads serving clients do not live long and most of the time they are waiting either to receive data from the client or to send it to the client - that is, they are waiting for some system calls to return. Creating an OS thread is quite an expensive operation, as is context switching between OS threads. If you want to be able to serve a lot of customers efficiently, you need to come up with something else. For example, callbacks, but they are pretty inconvenient (though there are different opinions on this).
Another option is to use non-blocking I/O in combination with some kind of implementation of user-space threads (fibers). In this article I will show you how to write all this with your own hands.
Once every true-linux engineer gets a trouble: there is no any software in his distro or it's built without needed options. I am keen on the phrase: "Only source control gives you freedom".
Of course, you can build this software on your computer without any src-packages, directly (with simplification: configure, make, make install). But it's a non-reproducible solution, also hard for distribution.
The better way is to make distro-aligned package that can be built if needed and that produces lightly distributed binary-packages. It's about debian-source packages(debian,ubuntu,etc), pkgbuild (for arch), ebuild for gentoo, src-rpm for red hat-based, and many others.
I will use cri-o like a specimen.
Before reading the text below I strongly recommend to get familiarized with the official Debian policy manual placed here and debhelper manpage.
Also you will be required to setup some variables like DEBMAIL and DEBFULLNAME for proper data in changelog and other places.
Typically when a Node falls out of the OpenShift cluster, this is resolved by simply restarting the offending element. What should you do, however, if you’ve forgotten the SSH key or left it in the office? You can attempt to restore access by using your wit and knowledge of Linux commands. Renat Garaev, lead developer at Innotech, described how he found the solution for this riddle and what was the outcome.
Sometimes all of us need to make a graphical installer for one's own linux distro. It goes without saying that you are able to use a distro-specific installer like Anaconda for RedHat-based or DebianInstaller for debian-based. On the other hand Calamares is a graphical installer which is not aligned with only one package manager.
I want to share my experience how to make a universal install solution with GUI. I did not find any complete article about it, hence, I reinvented the wheel.
I reinstalled both Windows and Linux (Fedora) recently on a notebook PC, and I decided to write the summary article about my experience with both OS. I'm also going to describe how to configure each OS via command-line and set up a dual-boot system.
Hi everyone, today I will tell how I restored a defunct LVM thinpool. Unfortunately I could not find any howtos or manuals on the internet, so maybe this one will help someone in a similar situation.
In this video, we will look at how to connect brushless motor controllers to a Linux computer. Specifically, we will use a computer running Debian. The same steps would work for Ubuntu Linux and other Linux distributions derived from Debian.
I've got a small sensorless brushless motor, and a bigger brushless motor with a built-in absolute encoder. Lets look at how to control those from my Debian Linux computer. Servosila brushless motor controllers come in several form factors with either a circular or a rectangular shape. The controllers come with a set of connectors for motors and encoders as well as for USB or CANbus networks.
The controllers can be powered by a power supply unit or by a battery. To spice up my setup, I am going to use a battery to power the controllers and thus their motors. The controllers need 7 to 60 volts DC of voltage input. If I connect the battery, the controllers get powered up. The small LED lights tells us that the controllers are happy with the power supply.
We need to connect the brushless motor controllers to the Linux computer. There are two ways to do that - via CANbus or via USB. Lets look at the USB option first. A regular USB cable is used. Only one of the controllers needs to be connected to a computer or a PLC.
Next, we need to build an internal CANbus network between the controllers. We are going to use a CANbus cross-cable to interconnect the controllers. Each controller comes with two identical CANbus ports that help chain multiple controllers together in a network. If one of the interconnected brushless motor controllers is connected to a computer via USB, then that particular controller becomes a USB-to-CANbus gateway for the rest of the network. Up to 16 controllers can be connected this way via a single USB cable to the same control computer or a PLC. The limit is due to finite throughput of the USB interface.
Setting up Atom for working with python is quite a tricky task. I've spent a lot of time making it work. Autocompleting, autoformatting, type hints, and much more will be available to you after reading this tutorial.
We describe the implementation of a custom Domain Name System (DNS) by using C socket programming for network communication, together with SQLite3 database for the storage of Internet Protocol (IP) for Uniform Resource Locator (URL). Then we provide a performance analysis of our implementation. Our code is available publicly [1].
