A little bit about me,

I'm Sergio,

Passionate about cybersecurity since I was 13 years old, when I began to explore technologies such as Kali Linux and Python. I have developed projects with Raspberry Pi and launched a technical tutorial blog (errorcomosolucion.com).

I have a Higher Degree in ASIR (2 years), a Master's Degree in Cybersecurity (1 year) and about 2 years of experience as a Sysadmin, mainly in Cloud (AWS and Azure). I was a finalist at Atenea, the CCN-CERT CNI challenge platform, and I completed a 250-hour cybersecurity course taught by INCIBE. I like challenges, am adaptable and have great patience to solve complex problems. I also have experience in the field of cybersecurity (about half a year) as an analyst, carrying out pentests, reports and performing other functions.

Cycling

I practice it as much as with friends and as a means of transport. I do all kinds of routes, from mountain roads, beach trails, short, medium and long bike/road lanes. The two most remarkable routes I have taken have been from Castellón to Culla (67km, 1000m of unevenness) and to Peñíscola (71km, 100m of unevenness)

Hardware maintenance

I have always preferred to take care of the proper functioning of my things myself (even when I had no knowledge in this field). I have also worked with other people's teams as a “freelancer”, modifying and repairing laptops, towers, etc. The most common problem is usually poor equipment performance.

Calisthenics

The discipline of Calisthenics has always been a branch of sport that caught my attention from a very young age. Training outdoors at a cost of 0€ and 24/7 availability has completely captivated me. On the other hand, it's a challenging sport, as progressing from a certain level is complicated. The only handicap is bad weather (sometimes).

My Skills

Technics

The base from which I start is my work as Sysadmin, in which I have about 2 years of experience. This gave me a very solid base of knowledge about:

  • DNS
  • Hostings
  • Databases
  • Redes
  • Cloud platforms (AWS, Azure... etc)
  • Operating Systems
  • Bastion of systems
  • Deployments and migrations
  • Backup plans
  • Etc

A skill that I practiced during the Master's degree and that I have consolidated during my work as a Cybersecurity Analyst with around half a year of experience to back it up. I have done various types of pentests:

  • Internal infrastructure
  • External infrastructure
  • Android app
  • iOS app
  • Pentest website
  • BEES

I have experience creating fairly large scripts, mainly in Bash and Python. Other alternative languages I've used are Powershell and KQL (among others)

Sociales

I understand the needs of others and adapt my approach to each situation, facilitating effective communication and harmonious teamwork.

I am able to speak and write:

  • Spanish (Native)
  • English (High)
  • Catalan (Medium)
  • Romanian (Low)

I have the ability to remain calm in challenging situations, allowing me to analyze problems clearly and find effective solutions.

Other

I enjoy what I do and commit to every task, ensuring quality results and a positive impact on my environment.

I don't give up easily in the face of obstacles; I seek solutions with determination until I achieve the objectives set.

I respond with serenity in high-stress situations, making rational and efficient decisions.
My Journey

Academic and professional

My Projects

Business

Deploy HashiCorp Vault

This project had the idea of managing all the secrets of a company (SSH accesses, SSO accesses and other digital identities) to access its machines and other elements. On servers alone, around 300 accesses had to be managed. The advantage of HashiCorp Vault is that it has access through roles and SSO, temporary accesses that are generated on the fly to access once, etc. This allows granular control of what happens with the secrets, who accesses them, when they access them, and so on. Another advantage was that you could assemble it manually with your own infrastructure through a Docker (which is how I did it), avoiding paying ridiculous fees as happens with other managers.

Infrastructure migration to Azure

The project consisted of a group of customers who have maintained their infrastructure on an old platform without changes or maintenance. Over the years, both the platform and the technologies used became completely outdated. This is where my profile comes in, I was responsible for designing an infrastructure of good practices (for example, the use of Entra ID instead of a domain controller installed on a server) with the new version of the applications, migration, security, maintenance plan, etc. All while keeping the budget of the cost of the infrastructure in affordable numbers for customers.

Exclusive pentest project for renowned company

I have led a project in which my working hours have been exclusive to the review of a very large company. During that time I developed a python script creating automations based on the Tenable Vulnerability Manager CSVs (a +1000 line script). The size of the project was more than 20k of vulnerabilities. It had to be managed in a period of time less than 4 months, with me being alone to carry out the execution of the project. Weekly client meetings, minutes, summaries and constant communication about the status of each department were also necessary. It was a highly stressful project to manage, but on the other hand, highly satisfying to solve. I consider it one of my greatest career milestones.

Personals

Error as a solution

This project was intended to be a page for tutorials, blogs, news about computer dissemination and others. I built this page based on WordPress together with Elementor, with its respective database and functionalities such as users who can post comments, etc. I couldn 't find the time necessary to get the project up and running or publish a reasonable number of posts to attract traffic. The reason was that during that time I had various personal problems, I studied and worked in hospitality, so I barely had time to rest. Despite this, I did have some reach and I was able to publish several blogs about computer science.

It is possible to browse the web today with archive.org (Wayback Machine) by clicking here (logically most of the elements are no longer interactable and you can see all the entries as if they were in production). Recently, I have dockerized the project and tried to make a version with the Hugo framework, but again the time I have is not enough for this project to end up being significant.

Local Cloud

As a good computer scientist who rewards privacy and freedom above all else, there came a point where I stopped feeling comfortable uploading my photos, my life and my privacy to the cloud. Because of this, I started downloading and deleting all the information I had on the internet to store it locally. In a first version of the NAS, I used a Raspberry Pi along with several modules that allowed me to connect hard drives and manage them under the O.S “TrueNAS”. Soon after, I saw the complexity of the system, which compared to my need was too high. Finally, I bought a Synology NAS that has most of the functionalities integrated with a simple click, with good management of encrypted content, good speed and versatility, since you can deactivate all the protections and modify them through an SSH terminal (since it is based on Linux).

I also combined this change with a migration of all my accounts to a password manager, activating MFA on as many accounts as possible. The next step was to create the backup and redundancy system for both the NAS and the credentials stored in the password manager (in case they fail).

YouTube Premium

This project is much less ambitious, since it was only trying to solve a specific need, but I extended the functionalities to make the use of the application more interesting. I developed a web server in python that connects to your personal YouTube API to display the playlists of your account with premium features (for example downloading music and videos). In my case, I needed this functionality because my car at the time only accepted an SD card to play music and many songs from the playlists disappear silently because the author hides or erases such content (or they even block the content from YouTube itself). Downloading the resources assures me that they will be 100% available to me. It should be noted that this way you should not see any ads (it would be very funny if they could sneak ads through the API).
Certifications, recognitions and recommendations

Certifications

Acknowledgments