The Identity Stack: From LDAP to Zero Trust

A 13-episode series on enterprise authentication — from the protocol that replaced /etc/passwd in the 1980s to Zero Trust identity and workload certificates in the 2020s.

Who it’s for: Linux administrators, DevOps engineers, and infrastructure security practitioners who have configured SSSD, joined machines to Active Directory, or debugged PAM — and want to understand why the stack is built the way it is.

# Query your enterprise directory
ldapsearch -x -H ldap://your-dc -b "dc=corp,dc=com" "(uid=you)" cn mail

# Get a Kerberos ticket, inspect it
kinit [email protected] && klist -e

# Trace an SSH login through PAM + SSSD
journalctl -u sssd -f   # then SSH in from another terminal

By EP12, you’ll enable SSH login to a Linux VM with Entra ID credentials and read every step in the auth log.

Episodes

EP	Title
EP01	What Is LDAP — and Why It Was Invented to Replace Something Worse
EP02	LDAP Internals: The Directory Tree, Schema, and What Travels on the Wire
EP03	How LDAP Authentication Works on Linux: PAM, NSS, and the Login Stack
EP04	SSSD: The Caching Daemon That Powers Every Enterprise Linux Login
EP05	How Kerberos Works: Tickets, KDC, and Why Enterprises Use It With LDAP
EP06	OpenLDAP Setup and Replication: Running Your Own Directory
EP07	LDAP High Availability: Load Balancing and Production Architecture
EP08	FreeIPA: LDAP + Kerberos + PKI in a Single Linux Identity Stack
EP09	How Active Directory Works: LDAP, Kerberos, and Group Policy Under the Hood
EP10	SAML vs OIDC vs OAuth2: Which Protocol Handles Which Identity Problem
EP11	Identity Providers Explained: On-Prem, Cloud, SCIM, and Federation
EP12	Entra ID Linux Login: SSH Authentication with Azure AD Credentials
EP13	Zero Trust Identity: SPIFFE, SPIRE, mTLS, and Continuous Verification

Start with EP01: What Is LDAP? →

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