Does mod_shib ever do AttributeQueries?

Tom Scavo trscavo at
Tue Apr 15 16:33:53 EDT 2014

On Tue, Apr 15, 2014 at 4:19 PM, Wessel, Keith <kwessel at> wrote:
> Thanks, Tom, that's a good start. I already checked, and should have included in my earlier note: all of these on-campus SPs are doing SAML2 attribute queries, and I know they're all running SAML2-compliant
> SPs.

Does your IdP *always* push attributes (if in fact there are
attributes to push)? If so, you can conclude these SPs are issuing a
redundant attribute query.

> Is mod_shib smart enough, if it receives an assertion without any attributes, to try an attribute query?

I wouldn't call that "smart" behavior but it's perhaps the only thing
the SP can do. If the SP doesn't get the attributes it wants, it can't
possibly know if the IdP is acting according to policy (no attributes
released, period) or if the IdP intends for the SP to query. If you
take the SAML2 AttributeService endpoint out of metadata, you force
the issue on the SP.

> If so, this could have been a fluke when the post content from the IDP didn't make it through to the SPs a hand full of times.

Not sure what you mean but in any case let me be explicit: 1)
configure your IdP to *always* push attributes, and then 2) remove the
SAML2 AttributeService endpoint from metadata. That brings you one
tiny step closer to where you want to be. The big question is: Can you
get away with not supporting SAML1?


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