Learning path
Security Protocols
Learners who already understand basic networking and want a rigorous, protocol-by-protocol understanding of how confidentiality, integrity, and authentication are achieved on the wire.
Go deep on how network security protocols actually protect data in transit: cryptographic fundamentals, then RFC-grounded, packet-by-packet internals of TLS, IPsec, SSH, and PKI.
Modules and lessons
Introduction to Network Security
The concepts every security protocol builds on: the CIA triad, common threats, symmetric and asymmetric cryptography, and hashing.
Security Fundamentals: Cryptography and the CIA Triad
Explain the CIA triad and common network threats, how symmetric and asymmetric cryptography and hashing provide confidentiality and integrity, and see a Diffie-Hellman key exchange derive a shared secret without ever transmitting it.
TLS
The protocol behind HTTPS: how TLS 1.3 negotiates a session in one round trip and encrypts everything that follows.
TLS: Transport Layer Security
Explain how TLS 1.3 negotiates a session with a single round trip, authenticates the server with a certificate, and protects application data, per RFC 8446.
IPsec
The network-layer protocol suite behind site-to-site and remote-access VPNs: security associations, AH versus ESP, and tunnel mode.
IPsec: Internet Protocol Security
Explain how IKEv2 negotiates security associations, the difference between AH and ESP, why tunnel mode is used for site-to-site VPNs, and how NAT traversal lets ESP survive address translation, per RFC 4301.
SSH
The protocol behind secure remote administration: public-key authentication, host-key trust, and multiplexed channels over one encrypted connection.
SSH: Secure Shell
Explain how SSH's transport layer establishes an encrypted session, why public-key authentication is preferred over passwords, how trust-on-first-use verifies a server's host key, and how one SSH connection multiplexes multiple channels, per RFC 4251.
PKI
The trust infrastructure behind TLS, IPsec, and SSH certificates: X.509 certificates, the chain of trust, and revocation.
PKI: Public Key Infrastructure
Explain what an X.509 certificate contains, how a chain of trust is verified from a leaf certificate up to a pre-trusted root, and how certificate revocation is checked, per RFC 5280.