linux on Developer's blog

Working With Multiple VPNs

Thu, 04 Aug 2022 18:00:00 +0000

I work on several projects. Each of them require a VPN connection. Sometimes, I work from remote locations and I need to access my home network. It’s one more VPN connection. It’s convenient to have an ability to access different private networks at the same time. Let’s discuss the issues of multi-VPN setups and possible.

TL;DR:

Use NetworkManager to manage VPN connections.
Disable systemd-resolved.
Use dnsmasq to process DNS requests.

How Much Access to RAM Costs

Mon, 17 Jan 2022 05:00:00 +0000

Every computer program uses the main memory (RAM) to store data. RAM is considered to be fast storage compared even to the fastest NVMe SSD or 100Gbit network. It seems that the RAM speed is high enough and that is why no optimizations are required: just read or write any memory cell when the program needs it.

From the famous article What Every Programmer Should Know About Memory, I’d found that memory access is more tricky than I used to think about.

Install Ubuntu on External Disk

Sat, 25 Dec 2021 10:00:00 +0000

Sometimes it can be useful to have an external HDD or SSD with a familiar environment installed. With such a device it’s possible to check the computer from eBay for GPU or memory faults, restore a primary OS of the workstation after an unsuccessful software update or just work on another PC with a familiar OS without any modifications of any software on this machine.

I use Ubuntu 20.04 as a primary OS, that is why in this article, I’ll explain how to install it on an external drive.

Network Tools

Sat, 15 May 2021 08:00:00 +0000

Almost every user sooner or later faces network problems, so it’s essential to have at least a basic understanding of network troubleshooting. In this article, I’d like to overview tools I use to explore network configuration and solve network issues on the Ubuntu desktop. Most of these applications can be used on a server but some of them are specific to desktop systems. ip and NetworkManager ip is a tool that allows to show or manipulate routing and network devices.

Wrong Copying Progress and Long Disk Unmounting on Ubuntu

Mon, 04 Jan 2021 11:00:00 +0000

Sometimes I need to copy files from an internal SSD to an external hard drive. Recently I’ve found a strange behavior on Ubuntu 20.04. When I try to copy a fairly big file (like 2Gb - 4Gb) Nautilus shows insane writing speed and the progress bar instantly reaches 100%, but when I want to unmount the device - it freezes for several minutes. I tried different file managers like Thunar from Xfce, midnight-commander, or even utilities like rsync or pv - the result was the same. For me, it’s a bit inconvenient when I don’t know how much time I have to wait until all data will be transferred, so I tried to find the solution to this problem.