disallow requests naming principal as a service

Nicolas Williams Nicolas.Williams at ubsw.com
Wed Mar 27 15:44:01 EST 2002

On Wed, Mar 27, 2002 at 03:34:49PM -0500, Sam Hartman wrote:
> >>>>> "Nicolas" == Nicolas Williams <Nicolas.Williams at ubsw.com> writes:
> It is
>     Nicolas> generally the case that Kerberos clients fetch service
>     Nicolas> tickets before attempting to connect to the services,
>     Nicolas> after all. 
> No, actually, neither SASL nor GSSAPI SPNEGO nor the GSSAPI support in
> Ssh does this.  In IETF protocols that use Kerberos, you tend to have committed to Kerberos before you get the service ticket.

Yes, I needed caffeine when I wrote that :)

> My main problem with the KDC negotiation of U2U is that encouraging
> its use encourages bad protocol design.  We want people to negotiate
> whether to use Kerberos at all; when they do that negotiation they
> might as well do the U2U negotiation at the same time.  So for
> properly designed protocols the KDC negotiation is unnecessary.

I now agree fully.

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