Percio Castelo.
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Percio Castelo.

SysAdmin & DevSecOps · 10+ years operating Linux servers in production, investigating root causes, and documenting hands-on solutions without fluff.

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Percio Castelo @sr00t3d
Linux SysAdmin & DevSecOps · Manaus, Brazil
Google Cybersecurity V2 · Cybersecurity Essentials (LFC108) · CWSA-2

The workbench philosophy

My background of over 10 years in Linux infrastructure was forged in sustaining mission-critical environments and delivering Tier 2/3 advanced technical support (including internal operations at HostGator and independent technical consulting): containing distributed denial-of-service attacks, untangling mail queue loops (Exim/Postfix), recovering crashed web clusters, and debugging MySQL desynchronizations and corrupted configuration files under heavy traffic.

This portal was born out of my daily workbench discipline: never settling for the lazy workaround of "restarting the service." Every article documents the real forensic workflow: what the logs uncovered, what the root cause was at the kernel or application layer, and what defensive hardening is needed so the incident never occurs again.

The methodology behind every article

Reproduction & real analysis

Scenarios based on authentic incidents across hosting environments, clusters, and cloud setups.

Authentic commands & logs

Zero generic handbook theories: real terminal outputs, CLI diagnostics, and lab-tested scripts.

Exact root-cause layer

Surgical inspection into filesystem permissions, I/O limits, network sockets, DNS, and syscalls.

Hardening & prevention

Definitive configuration tweaks and security policies engineered for continuous production uptime.

The lab: NEXUS ecosystem

Today, this infrastructure experience directly powers my research and active development in Docker containers, automated CI/CD security pipelines, and defensive engineering. Beyond day-to-day operations, I build NEXUS: an authorial ecosystem featuring dozens of plugins for threat intelligence, OSINT, vulnerability scanning, and an integrated MCP server.

My hands-on transition into DevOps and DevSecOps is the natural evolution of someone who spent nearly two decades operating servers from the bare command line, now channeling that exact operational rigor into predictable, resilient automation.

How I work: predictability, documentation, and team collaboration

Experienced hiring managers look for operational predictability and team collaboration, not lone wolves. Over a decade leading technical support and sustaining critical production fleets under pressure, I established clear operational principles:

Runbook Culture

Every architecture automation or emergency fix is delivered with reproducible technical documentation so any teammate can operate and scale autonomously.

Asynchronous Transparency

Structured logs, objective post-mortems, and transparent root-cause analysis aligning technical metrics with business bottom-line.

Peer Review & CI/CD

Preventive automation with strict security gates before deploys, mitigating configuration drift and human errors before production impact.

Governance & SLAs

Disciplined operations with controlled maintenance windows, pre-tested rollback plans, and strict adherence to service availability SLAs.

Explore the site

Systems Administrator · Mission-Critical Infrastructure

Let's talk about your critical infrastructure

10+ years maintaining mission-critical Linux environments, running authorial cloud infrastructure on Oracle Cloud, and continuously mastering AWS, Azure, and GCP, ready to add engineering firepower to your team.

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