Konstas — Engineering Notes

Konstas · Engineering Notes
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 ├─ Articles            Networking · Cybersecurity · Cryptography · Telecom · Virtualization · Systems
 │   ├─ Mastering OSPF  CCIE series on link-state routing — areas, LSAs, summarization
 │   └─ CCIE Labs       38 hands-on labs across two full 20-router topologies
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 ├─ SENTINEL           autonomous defense platform — live signal, quantum-safe crypto
 ├─ The Stack          security & infrastructure project index
 ├─ LLM                AI Large Language Model platform & services
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 ├─ Security Awareness  plain-language guides for a non-technical audience
 ├─ Data Science       applied ML, statistics, MLOps
 ├─ Information Security  CCIE & CISSP study notes and blueprints
 ├─ Readings           curated security papers
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 └─ About

Latest Report

OSPF Micro-loops: Transient Loops During SPF Convergence

Every router floods the same LSAs and reaches the same SPF result, just not at the same moment. How that creates local and remote cross-point loops, how to report them, and how TI-LFA and SR remove them.

New · Mastering OSPF · Chapter 06

Konstas Markets Desk: An FX Dealing Room on One Mac

A complete FX dealing-room training system: eight competing banks, Reuters-style conversations, client calls, forwards and money markets, a full back office, and every ACI Dealing formula.

New · Trading Systems

TCP/IP: The Protocol Suite Behind the Internet

From ARPA experiments to the Internet's common language: milestones, the four layers, Internet governance and how RFCs become standards.

New · Networking

Diplomacy in the Age of Code: Blinken at the RSA Conference

Six foundational technologies, cyber-physical risk, AI governance and trusted supply chains, with what it means for security practitioners.

New · Policy & Security

OSPF Cost Calculation: How a Summary LSA Becomes a Routing Table Entry

The Type-3 LSA says 1001, the routing table says 1002. Why the router adds its own cost to the ABR, how two ABRs are compared, and why OSPF is "distance vector between areas".

New · Mastering OSPF · Chapter 05

OSPF Type-5 LSAs: The Missing Link Between Intra-Area and Inter-Area Reachability

A Type-5 LSA describes the destination, not the path. How routers reach the ASBR through Type-1/2 and Type-4 LSAs, and why E1 makes that path count.

New · Mastering OSPF · Chapter 04

Mastering OSPF: A CCIE Series on Link-State Routing

Area types and hierarchy, summarization, DMVPN overlays, Type-4/Type-5 external routes, how inter-area metrics are calculated, and the micro-loops SPF convergence leaves behind. Six chapters, with OSPFv3 next.

New · Networking · CCIE Series

The CDP Flood: A Layer 2 Denial-of-Service Demo

Articles · September 2026 · Ioannis (John) Konstas

Offensive Security

Gatekeeping the Built-In Administrator: A Break-Glass Blueprint for the RID-500 Account

Most organizations still have the RID-500 Administrator enabled. How to vault it under dual custody, isolate it to Tier 0, deny it everywhere by GPO, and alarm every use.

New · Identity Security

Mutation-Based Fuzzing: From Commodore 64 POKEs to Drone Firmware

Working Python mutators for text and checksum-valid MAVLink telemetry, how binary fuzzers get coverage without source code, and a field guide to firmware and UAV fuzzing tools.

New · Offensive Security

Maximizing Bitcoin Analytics with Local Snapshots

How a full Bitcoin snapshot (~700 GB) with txindex enables high-speed offline analytics, Electrum/Esplora indexing, and privacy-preserving blockchain research.

New · Cryptography & Bitcoin Infrastructure

SENTINEL: An Autonomous, Quantum-Safe Defense Platform

A security platform I designed and operate on Zero Trust, active deception, and post-quantum cryptography (FIPS 203/204) — built as a closed-loop, self-correcting system rather than a passive alert stream.

New · Security Operations

SENTINEL Mobile Shield: Hardened Endpoint Security & Zero-Trust Tunnel Architecture

Mobile security architecture and capability overview: dual-stack ChaCha20-Poly1305 encryption, live-path inline intrusion detection, DNSSEC-validated DoH, and zero-trust per-device isolation.

New · Security Architecture

Essential Tooling & Platform Resources for Engineering, Security, and Analytics

Articles · August 2026 · Ioannis (John) Konstas

Architecture

Strategic Business Impact Planning Techniques

An academic analysis of business–information systems alignment, competitive advantage, and strategic value creation across the seminal SISP frameworks (Porter, McFarlan, Parsons, Benjamin, Rackoff, Rockart), 1979–1991.

Information Systems Strategy

Networking

BGP and Autonomous Systems: Routing You Can Trust

Articles · July 2026 · Ioannis (John) Konstas

Networking

Cisco CSR1000v: Converting Serial Consoles to a Secure REST API

Cisco CSR1000v instances running on ESXi expose their consoles via serial-over-network — Telnet sessions mapped to incremented ports (2301–2320). This is…

Networking

Cisco Device Hardening: Disabling Call Home and Controlling Outbound Communications

Cisco networking equipment ships pre-configured with telemetry and support features — including Call Home, Smart Licensing transport, and HTTP management…

Networking

Cisco IOS Path Selection: How a Router Chooses the Best Route

Articles · July 2026 · Ioannis (John) Konstas

Networking

Cisco IOS Survival: Password Recovery, ROMMON, and SSH

Articles · July 2026 · Ioannis (John) Konstas

Networking

Cisco Nexus 1000V Port Channels and Trunking: Troubleshooting Guide

End-of-Life Notice: Cisco announced End-of-Sale for the Nexus 1000V for VMware vSphere in 2019 and End-of-Support in 2025. This product should not be…

Networking

Cisco UC500 / CME Lab: Unified Communications Manager Express Configuration

Architecture of CME 8.6 on a UC520, SCCP ephone configuration, FXO/FXS voice ports, DHCP for phones, CUE module, and Python serial console automation.

Networking

Firewall Architectures, From Packet Filters to Zero Trust

Articles · July 2026 · Ioannis (John) Konstas

Networking

Floating Static Routes: Backup Path Selection in Cisco Networks

Articles · July 2026 · Ioannis (John) Konstas

Networking

Inside Classified Networks: NIPRNet, SIPRNet, and JWICS

Articles · July 2026 · Ioannis (John) Konstas

Networking

SD-WAN Lab Blueprint — Cisco CSR1000v v17.03.03

Three CSR1000v edges dual-homed across two independent transports for automatic failover, with a full SD-WAN controller stack — vBond, vSmart, vManage — plus the underlay OSPF and overlay configuration.

Networking

The OSI and TCP/IP Models, Revisited

Articles · July 2026 · Ioannis (John) Konstas

Networking

VMware SD-WAN VeloCloud: Security Hardening Guidelines

Compromised network devices can be used to redirect traffic, exfiltrate data, and pivot into internal systems — making SD-WAN Edge hardening a critical part…

Networking

Voice VLAN Design: PoE Switch Configuration and Cisco IP Phone Provisioning

Separating voice and data traffic with IEEE 802.1Q VLANs, PoE switch configuration, TFTP/DHCP provisioning for Cisco IP phones, and the SCCP boot sequence.

Networking

Network Jitter, Standard Deviation & Bandwidth Measurement

Articles · July 2026 · Ioannis (John) Konstas

Networking

Network Automation

Wrapping Legacy Network Gear in a Modern API

Turning legacy Telnet-only router consoles into an authenticated REST API with total network isolation, the Netmiko alternative for SSH-native fleets, and the roadmap toward a full automation platform.

Automation

Mastering OSPF

Mastering OSPF — A CCIE Series on Link-State Routing

Area types and hierarchy, LSA filtering, OSPF vs BGP summarization, the DMVPN overlays OSPF runs across, how Type-4 and Type-5 LSAs resolve external routes, how inter-area metrics are calculated, and why SPF convergence causes transient micro-loops. Each chapter explains why OSPF behaves as it does, not just how to configure it. OSPFv3 is next.

Series · 6 Chapters · CCIE

CCIE Labs

CCIE Advanced Lab — 20-Router MPLS + DMVPN Topology

20 hands-on labs on one 20-router topology: MPLS core with LDP and L3VPN, dual DMVPN clouds, BGP route reflection and confederations, OSPF/EIGRP design, multicast, QoS, traffic engineering and 6PE.

CCIE Lab

CCIE Enterprise Lab — 18 Labs, Full EI v1.0 Blueprint

18 labs covering 100% of the CCIE Enterprise Infrastructure v1.0 blueprint across five domains: campus switching, routing protocols, transport (MPLS/DMVPN/FlexVPN), security and services, and automation.

CCIE Lab

Virtualization & Infrastructure

ESXi CPU Temperature Monitor: A Shell Script for Real-Time IPMI Alerting

ESXi does not ship with a continuous, color-coded temperature dashboard. If you manage bare-metal hosts in a lab or production environment and want immediate…

Virtualization

ESXi Recovery Playbook: hostd, localcli, vim-cmd, and Log Triage

When the vSphere client cannot reach an ESXi host and PowerCLI connections time out, the management agent (hostd) has likely crashed or failed to start. This…

Virtualization

PowerCLI ESXi Shutdown: Code Review and Production Rewrite

The original PowerCLI shutdown script circulating across VMware communities is widely copy-pasted into production runbooks. It works in a lab — but it has…

Virtualization

VMware ESXi Hardening: A 45-Control Security Configuration Assessment

ESXi hypervisors are the foundation of every virtual infrastructure — and because every workload runs on top of them, a misconfigured host is a single point…

Virtualization

VMware Infrastructure Architecture Overview

Historical reference: This article documents the VMware Infrastructure 3 / early vSphere architecture. Components referenced here — ESX Server, VirtualCenter…

Virtualization

VMware vSphere 7 Security Configuration Guide: A Practitioner's Overview

The VMware vSphere Security Configuration Guide (SCG) is the official baseline for hardening and auditing vSphere infrastructure. Version 7 — which…

Virtualization

Cybersecurity

A Field Guide to Denial-of-Service Attacks

Articles · July 2026 · Ioannis (John) Konstas

Cybersecurity

Building an Open-Source Security Monitoring Stack

Articles · July 2026 · Ioannis (John) Konstas

Security Operations

Deepfakes: How They Work and How to Spot Them

Articles · July 2026 · Ioannis (John) Konstas

AI & Security

Formal Security Models: Bell-LaPadula and Biba

Articles · July 2026 · Ioannis (John) Konstas

Foundations

Information Security Fundamentals: CIA, Risk, Access Control, Cryptography & Compliance

Sound information security practice rests on a small number of foundational concepts that appear repeatedly across every framework, standard, and regulation…

Security

Penetration Testing, End to End

Articles · July 2026 · Ioannis (John) Konstas

Offensive Security

Ransomware Defense in 2026

Articles · July 2026 · Ioannis (John) Konstas

Cybersecurity

Penetration Testing Professional Reference Guide

Articles · July 2026 · Ioannis (John) Konstas

Offensive Security

An OWASP Top 10 File Scanner with Live Malware Lookups

Articles · September 2026 · Ioannis (John) Konstas

Defensive Security

Mutation-Based Fuzzing: From Commodore 64 POKEs to Drone Firmware

Articles · September 2026 · Ioannis (John) Konstas

Offensive Security

Memory Safety, Buffer Overflows & Baggy Bounds

Articles · July 2026 · Ioannis (John) Konstas

Offensive Security

SENTINEL Mobile Shield: Hardened Endpoint Security & Zero-Trust Tunnel Architecture

Articles · September 2026 · Ioannis (John) Konstas

Security Architecture

Layered Security Stack

Articles · July 2026 · Ioannis (John) Konstas

Architecture

Restoring Microsoft 365 Mail Flow After a Domain Re-Add

Articles · July 2026 · Ioannis (John) Konstas

Email Security

Endgame and the Blurring Line of Cyber Warfare

Articles · July 2026 · Ioannis (John) Konstas

Cybersecurity

Meta / Facebook Surveillance Architecture & Technical Privacy Defense

Articles · July 2026 · Ioannis (John) Konstas

Privacy

Cryptography

TTB COLA Label Compliance AI Inspector

Automated sub-second 27 CFR Label Verification & Compliance Audit System for TTB agents — verifying brand names, ABV/proof consistency, standards of identity, and strict Part 16 Government Health Warnings with interactive bounding box canvas and batch importer.

September 2026 · Interactive AI Tool

Complete Reference Guide: Modular Arithmetic & Equivalence Classes

A self-contained reference guide bringing together core principles, definitions, equivalence classes modulo 8, calculation methods, and representative invariance proofs in modular arithmetic.

September 2026 · Cryptography

Overview of Cryptology: Taxonomy, Primitives, and Cryptanalysis

A comprehensive architectural overview and taxonomy of modern cryptology — spanning Cryptography (Symmetric, Asymmetric, Protocols) and Cryptanalysis (Mathematical, Side-Channel, Quantum threats).

Cryptography

Why 26! ≈ 2⁸⁸: Substitution Cipher Key Space, Bit Depth & Mental Estimation

Converting the 26! alphabet permutations of simple substitution ciphers into base-2 logarithmic bit depth (2⁸⁸), Python verification, and 3 mental arithmetic shortcuts.

Cryptography

Public-Key Cryptosystems Based on the Discrete Logarithm Problem

Mathematical reference on the Discrete Logarithm Problem (DLP), Diffie-Hellman Key Exchange (DHKE), and the ElGamal Public-Key Cryptosystem — mechanics, security proofs, and applications.

Cryptography

A Cascade of Factoring Techniques: From Pollard's Rho to the General Number Field Sieve

While the General Number Field Sieve (GNFS) remains the premier method for factoring very large integers, other techniques are used depending on the size of…

Cryptography

Advanced Integer Factorization Using the Quadratic Sieve Algorithm

This document covers the design and implementation of an efficient integer factorization tool using the Quadratic Sieve (QS) algorithm.

Cryptography

Expert Review: Energy-Efficient Approaches to the General Number Field Sieve

The project proposal accurately identifies a critical nexus in modern computational security: the convergence of classical cryptanalysis, high-performance computing, and sustainable computing.

Cryptography

Extended Euclidean Algorithm, Euler's Theorem & Cryptological Applications

The Greatest Common Divisor (GCD) of two integers is the largest integer that divides both without remainder — Euclid's algorithm computes it in O(log min(a,b)) steps.

Cryptography

Galois Fields in AES — Reference

Mathematical reference for the Galois Field arithmetic that underpins AES encryption. Covers GF(2⁸) structure, polynomial representation, the AES irreducible…

Cryptography

Galois Fields in AES: GF(2^8), Irreducible Polynomials, and the Extended Euclidean Algorithm

AES — the symmetric cipher protecting the majority of encrypted data on the internet — is built on a branch of mathematics that most engineers never…

Cryptography

Post-Quantum Cryptography Is Now a Deadline

Articles · July 2026 · Ioannis (John) Konstas

Cryptography

Side-Channel and Timing Attacks

Articles · July 2026 · Ioannis (John) Konstas

Cryptography

Maximizing Bitcoin Analytics with Local Snapshots

A full Bitcoin snapshot (~700 GB) enables advanced analytics, development, and privacy-focused operations with rapid offline querying and indexing.

Cryptography · Blockchain Analytics

Bitcoin & Crypto Node Tools

Articles · July 2026 · Ioannis (John) Konstas

Cryptography

Bitcoin Blockchain Data Platform & Genesis Block Deep Dive

Articles · July 2026 · Ioannis (John) Konstas

Cryptography

Telecom & VoIP

A2Billing VoIP Billing Engine: Architecture, AGI Integration, and Rate Management

How A2Billing integrates with Asterisk via AGI for real-time call billing, rate deck structure, calling card IVR flow, and MySQL database schema.

Telecom

Asterisk PBX Architecture: Channel Drivers, Dialplan Engine, and AGI Integration

Core Asterisk components — chan_pjsip, extensions.conf dialplan logic, AGI scripting, AMI/ARI interfaces, CDR to MySQL, and STIR/SHAKEN configuration.

Telecom

Building a Production CLEC Stack: Asterisk 22 + Kamailio 5 + A2Billing on Docker

This article documents the full integration of a production-grade Competitive Local Exchange Carrier (CLEC) platform using Asterisk 22, Kamailio 5, and…

Telecom

Carrier-Grade SIP Infrastructure: 10-VM Open Source Telecom Stack Architecture

Architecture, network segmentation, jumbo frames, and call flow for a production VoIP carrier stack built entirely on open source software.

Telecom

Docker VoIP Stack: Boot Sequencing, Health Checks, and Dependency Management

How to correctly order Docker container startup for a Kamailio + Asterisk + A2Billing stack using health checks, and bridging VLAN-isolated IP phones via a Python SIP relay.

Telecom

Kamailio SIP Server: Proxy, Load Balancer, and Session Border Controller

Architecture, core modules, dispatcher load balancing, fraud protection, TLS, and RTPEngine integration for Kamailio in a production VoIP platform.

Telecom

RTPEngine: Media Proxy for VoIP — NAT Traversal, Transcoding, and SRTP

How RTPEngine solves NAT, codec mismatches, and media security in a Kamailio-based VoIP platform, with configuration and capacity reference.

Telecom

SS7 (Signaling System No. 7) — Technical Reference

Signaling System No. 7 (SS7) is an architecture for performing out-of-band signaling in support of the call-establishment, billing, routing, and information-exchange functions of the PSTN.

Telecom

STIR/SHAKEN: FCC-Mandated Call Authentication for VoIP Carriers

How STIR/SHAKEN works, attestation levels A/B/C, PASSporT token structure, STI-CA certificate requirements, and Asterisk implementation.

Telecom

Communications

HF Point-to-Point CommunicationHarris Modem Interface, STANAG Waveforms & Signal Processing

A technical framework for High Frequency point-to-point communication using Harris military-grade modems, covering the full stack from ionospheric propagation theory through hardware.

Communications

High-Frequency Radio: Still Vital in a Satellite World

Articles · July 2026 · Ioannis (John) Konstas

Communications

Always Studying

Information Security — CCIE & CISSP Study Notes

Blueprints and review notes tracked as I work through the CCIE Enterprise Infrastructure lab track and the CISSP common body of knowledge.

CCIE · CISSP