ECITIS Teacher · Networks · Systems · Security
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Emiliano Castellina
STEM teacher: Mathematics, Physics, Computer Science, and Networks & Systems. Here you'll find guides, notes and educational material for students and enthusiasts.
Multimedia Encoding — TPSIT Exercises
Step-by-step calculator for the six classic TPSIT exercises: print size in cm from Mpx, video+audio bit rate, image size (True Colour, 4 bit, palette) and Run-Length encoding on an 8×8 grid.
TLS/SSL — Secure Communication on the Web
A complete guide to TLS/SSL: evolution from SSL 2.0 to TLS 1.3, layered architecture, step-by-step handshake (TLS 1.2 and 1.3), the X.509 certificate chain, cipher suites with Forward Secrecy, AEAD and practical inspection tools.
The Diffie-Hellman Key Exchange
A complete explanation of the Diffie-Hellman key exchange: from pre-1976 symmetric cryptography to modular arithmetic, the discrete logarithm problem, the DH algorithm with a numerical example (p=23, g=5), and the elliptic curve variant (ECDH).
Local Network Design — Part 3: Security and Regulations
Third part of the local network design guide: perimeter defence with firewalls and DMZ, traffic filtering with standard and extended ACLs, secure remote access via VPN, and compliance with European GDPR and NIS 2 Directive regulations.
Local Network Design — Part 2: Bandwidth, VLANs, IP and Services
Second part of the local network design guide: WAN bandwidth calculation, failover, VLAN 802.1Q segmentation, IP addressing plan with CIDR subnetting, and DHCP, DNS and NAT/PAT service configuration.
Local Network Design — Part 1: Physical Infrastructure and WLAN
First part of the local network design guide: structured cabling hierarchy, Ethernet cable categories, fibre optics, Power over Ethernet and wireless network architecture.