[Freeipa-users] Understanding role of the certificate in client - server communication.

[Alexander Bokovoy]

On Wed, 19 Mar 2014, Genadi Postrilko wrote:
>Thank you for the answer.
>Sory if i lack the knowledge, but why SSL is needed when using kerberos?
>Kerberos is based on 3th party that is trusted, why there is a need for
>public key encryption?
Using Kerberos only, without asking for integrity and confidentiality
services,  without channel bindings to the outer encryption, is prone to
MITM even with valid TLS channels.

Use of certificates allows to perform mutual authentication at the SSL
level and later perform channel bindings of the tunnelled Kerberos
communication.

Note that Kerberos over HTTP is weak without transport level security.
HTTP authentication per se is independent of the transport.

For more details you can look at Joe Orton's talk at ApacheCon'2008:
http://www.apachecon.com/eu2008/program/materials/kerb-sso-http.pdf
-- 
/ Alexander Bokovoy