Red Hat Summit14.3. Kerberos authentication indicators
The Kerberos Key Distribution Center (KDC) attaches authentication indicators to a ticket-granting ticket (TGT) based on which pre-authentication mechanism the client used to prove its identity:
otp- two-factor authentication (password + One-Time Password)
radius- RADIUS authentication (commonly for 802.1x authentication)
pkinit- PKINIT, smart card, or certificate authentication
hardened- hardened passwords (SPAKE or FAST)[1]
The KDC then attaches the authentication indicators from the TGT to any service ticket requests that stem from it. The KDC enforces policies such as service access control, maximum ticket lifetime, and maximum renewable age based on the authentication indicators.
- Authentication indicators and IdM services
- If you associate a service or a host with an authentication indicator, only clients that used the corresponding authentication mechanism to obtain a TGT will be able to access it. The KDC, not the application or service, checks for authentication indicators in service ticket requests, and grants or denies requests based on Kerberos connection policies.
If a service or a host has no authentication indicators assigned to it, it will accept tickets authenticated by any mechanism.
[1]
A hardened password is protected against brute-force password dictionary attacks by using Single-Party Public-Key Authenticated Key Exchange (SPAKE) pre-authentication and/or Flexible Authentication via Secure Tunneling (FAST) armoring.
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