What Happens When A Linux Process Goes To Sleep?

 Posted on March 10, 2022  |  15 minutes  |  Sergio Guillen  • Also in: Español

It is possible when you are writing code, at some point you might need to pause the execution of a process by calling the sleep(NUMBER_OF_SECONDS) function depending on the problem you are solving. In this post, I will share what I learned so far while investigating the internal kernel mechanisms that make the sleep function work the way it does. I appreciate your feedback. I am not an expert on this topic as Linux Kernel’s internals are new for me, it was just my curiosity that drove me to get into kernel’s source code, and wanted to share what I learned. [Read More]

Analyzing a Video Looking for Possible Malware

 Posted on November 26, 2019  |  16 minutes  |  Sergio Guillen  • Also in: Español

Hello, during the months of October and November different social and political conflicts occurred in Bolivia, this entry is not so much to discuss the political issue, it will be a 100% technical entry but it is related to those events. The previous week a large number of clients from a local ISP received an SMS with a link bit.ly to an MP4 video in Dropbox that was later deleted. [Read More]

Automating post-installation setup in my personal Debian machines

 Posted on May 13, 2019  |  5 minutes  |  Sergio Guillen  • Also in: Español

Hi, some time ago I posted about my initial setup in my Debian personal machines that use for work or personal projects. Some of the things I setup are: applications, desktop look and feel, etc. The last months I installed and re-installed my Debian machines so many times in different computers that I use (new computers, new hard drives, etc.) and this taks was repetitive. Basically what I was doing was to review my previous blog post and repeat those steps. [Read More]

Fun with SSH - Local Port Forwarding

 Posted on August 28, 2018  |  8 minutes  |  Sergio Guillen  • Also in: Español

The other day when I went out eating with my friend Francisco, he commented me about a personal project and what he wanted to accomplish. Listening to his questions the first tool that came to my mind that would solve some of the challenges he has was OpenSSH. What is SSH? SSH is a short for Secure Shell, it’s a protocol to manage services inside a network using a secure channel. [Read More]

Gocho, Sharing files in a local network

 Posted on March 29, 2018  |  10 minutes  |  Sergio Guillen  • Also in: Español

Hey,during my free time I was working a side project called Gocho. This application allows the user to share files in a local network e.g. home network, work, etc. with the difference that it will auto-discover other nodes. In this post I will explain what this application is all about, why I wrote it and some challenges that came up duting the development. Why I wrote this app? First I wanted to share a directory in a local network without the need of others having to ask for my local ip address or the port where I published the files. [Read More]