The RPM is missing dependency for cyrus-sasl-plain in the package specification that is needed for PLAIN / LDAP authentication to work. This does seem to be fine for Debian as libsasl2 covers all authentication mechanisms. This results in following error on the server start and is not very helpful to diagnose the cause:

mongod --smallfiles --dbpath data --setParameter authenticationMechanisms=PLAIN --setParameter saslauthdPath=/var/run/saslauthd/mux
2014-10-01T14:47:42.204-0400 SEVERE: Failed global initialization: BadValue SASL(-4): no mechanism available: Couldn't find mech PLAIN