Shibboleth on 64-bit Linux with 32-bit Apache: "mod_shib_22.so: wrong ELF class: ELFCLASS64"

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Product: Aleph
Product Version: 20, 21, 22, 23
Relevant for Installation Type: Dedicated-Direct, Direct, Local

Question
Advice is sought on installing Shibboleth on 64-bit Linux, to work with (Ex Libris supplied 32-bit) Apache, as referenced in the PDS manual. This is in order to be able to run a Shibboleth service provider on the Aleph, and authenticate patrons using our separate SAML-compliant IdP.

We are running RHEL6, with Apache 2.2 as supplied as part of the v22 Aleph installation package. We have installed the Shibboleth pre-requisites from the Shibboleth repository, and built Shibboleth 2.5.5 from source. After configuring Apache to load the Shibboleth module, it fails to start with the message ‘mod_shib_22.so: wrong ELF class: ELFCLASS64’
Ex Libris have confirmed that this is because they are running 32bit Apache and do not support 64-bit Apache or Shibboleth. Does anyone have any experience of building 32-bit versions of Shibboleth on a 64-bit Linux OS?

Answer
The University of Maryland has used Shibboleth with PDS for many years (with PDS running under Metalib, but things should be identical under Aleph)....

In the past, we built shibboleth from source (on Solaris, where 32-bit was the default). When we migrated to RHEL 6.7 we used a pre-built package instead. See https://wiki.shibboleth.net/confluen...inuxRPMInstall for instructions.
Be sure to get the i686 version.

Our configuration:
Metalib 4.5.5
Apache 2.2.25 (from the Metalib distribution) PDS 2.1.1.009
shibboleth-2.5.4-3.1.el6.i686
-- but loading the latest version is recommended

You should be able to build the 32-bit version from source. There is probably a parameter in the configure script to do so. You would also need to build (or download) 32-bit versions of all the required libraries.

There is a warning in the page referenced above about installing both 32-bit and 64-bit versions. You may need to uninstall some of the pieces you already have.

Article last edited: 02-Mar-2016