I would like to reopen this issue, as it is still not completely
resolved, even in stretch / current sasl from git.
A 'normal' authentication works, but proxy authentication is broken
since wheezy, as long as sasl has no auxprop module configured.
The current workaround is to configure any auxprop module, even if the
backend (i.e. sasldb - easiest to configure) provides no authentication
results.
The latest discussion on this topic I could find, points out, that there
is still some unresolved issue in cyrus sasl:
https://lists.andrew.cmu.edu/pipermail/info-cyrus/2016-November/039241.html
