viot@netrunner:~$ ΕΛ

> whoami

Konstantinos Papakonstantinou

Security & Network Operations · MSc Cybersecurity

I work in security and network operations, and in my own time I build labs: networks to attack, then defend. Firewalls, IPS rules, WAFs and kernel hardening. This site is my notebook: what I tried, what broke, and what I learned.

location
Athens, GR
mindset
purple team
status
online
  • FortiOS
  • Junos Space
  • Snort IPS
  • Wireshark
  • iptables
  • ModSecurity
  • Nmap
  • Python

Latest from the lab

  • write-upcryptographypython I audited my own password manager, then rewrote it

    Good primitives are not a secure system. What a security audit of my own Python password manager found, how version 2 is designed, and five bugs that only appeared when I ran it.

  • forensicsdfirwindowsllm A Windows 11 forensics case, and an AI agent for triage

    A course forensics case on an encrypted Windows 11 VM: handling the evidence, mapping the findings to MITRE ATT&CK, and what an LLM agent can and cannot do for triage.

  • architectureiotprivacy Designing a secure smart-city IoT architecture

    A layered edge-to-cloud design for city cameras, traffic sensors and street lighting, and the controls that keep one hacked lamp post from reaching the rest.

all posts →

Labs & projects

SecureVault: an offline password manager

Python · Argon2id · AES-256-GCM · PySide6 · Windows & Linux

A password manager that keeps everything in one encrypted file on your own disk: no cloud, no telemetry, one runtime dependency. Version 2 is a ground-up rewrite that followed a security audit of my own first version.

  • Argon2id calibrated per machine, a random vault key, and AES-256-GCM over all data, so even site names stay encrypted
  • Tamper-evident file format with a written specification and threat model
  • Clipboard auto-clear kept out of Windows clipboard history, TOTP codes, password-health audit
  • CLI and desktop app; 300+ tests, including official RFC test vectors and bit-flip property tests
read the write-up

AI-assisted digital forensics

DFIR · MITRE ATT&CK · FastAPI · Streamlit · Ollama

Two forensics projects: a Windows 11 case analysed across seven evidence sources and mapped to ATT&CK, with an LLM agent for triage; and a network log analyzer that detects beaconing, DNS tunnelling and lateral movement with plain statistics, then lets a local model write the summary, so no evidence leaves the machine.

windows 11 case network log agent

Secure smart-city architecture

IoT · edge computing · PKI / mTLS · segmentation · GDPR

A layered edge-to-cloud security design for city cameras, traffic sensors and street lighting: segmentation against lateral movement, device certificates, zero-trust access, and privacy by design at the edge.

read the write-up

IoT sensor app with replay protection

IoT · accelerometer · heat index · team project

Posture and fall detection from an accelerometer, a heat-index comfort reading, and a per-message nonce against replayed sensor data.

read the write-up

Air-quality machine learning

scikit-learn · PyTorch · DBSCAN · SVM · team project

Madrid air-quality data: density-based clustering to separate pollution episodes, CAQI classification, and a neural network made more stable with transfer learning.

read the write-up

About

I go by viot online. I have more than a year of hands-on experience across network and security operations, helpdesk support and system administration. Today I work as a Security & Network Operations Engineer, running Fortinet firewalls and Juniper devices, triaging alerts in a 24/7 environment, and automating the repetitive parts with Python.

Alongside work I am studying for an MSc in Cybersecurity & Data Science at the University of Piraeus. My interests are network security, digital forensics and embedded/IoT security, and I learn best by building something, breaking it, and writing it down.

Experience

  1. Jun 2026 – present · Athens, GR · hybrid

    Security & Network Operations Engineer · Neurosoft S.A.

    • Administer and troubleshoot Fortinet firewalls (FortiOS), resolving connectivity and policy incidents.
    • Manage and monitor Juniper network devices through Junos Space.
    • Monitor alerts, email queues and tickets in a 24/7 environment, with triage and L2/L3 escalation.
    • Write Python scripts that automate recurring operational tasks.
  2. 2024 – 2025 · Athens, GR

    IT Support & Helpdesk Technician

    IT Field Technician at Teleperformance · Technical Support Staff (Helpdesk) at CQS S.A.

    • First-line support by phone, email and remote session, with tickets managed to SLA targets.
    • Active Directory administration: password resets, unlocks, RBAC permissions, and GPO deployment.
    • Diagnosed TCP/IP, DNS, DHCP and VPN issues; maintained workstations and peripherals.
    • Triaged high-volume requests on-site and remotely, escalating critical failures to L2/L3.

Skills

Network & security
FortiOS · Junos Space · Wireshark · Snort IPS · iptables · ModSecurity · Nmap
Offensive & testing
Burp Suite · Metasploit
Systems & programming
Windows Server / Active Directory · Linux · Python · SQL · Bash · C · Assembly
Operations & tooling
Jira · ServiceNow · VirtualBox · VMware · Git · Microsoft 365

Education

  1. in progress · expected 2027

    MSc in Cybersecurity & Data Science · University of Piraeus

    Network Security, Malware Analysis, Digital Forensics, Intrusion Testing, IoT & Hardware Security, Machine Learning.

  2. 2025

    BSc in Computer Science & Telecommunications · University of Thessaly

    Thesis: design and simulation of Arduino-based embedded circuits and sensors (Tinkercad, Wokwi).

  3. certification

    Pedagogical and Teaching Competence

Contact

Questions about a lab, or found a mistake in a post? Email is the best way to reach me.

[email protected] linkedin