RFC Authorizations
The authorization
check uses authorization object
S_RFC to check
whether the user defined in the destination has RFC authorization for the
function module to be called. The authorization check is performed at the
function group level. If the user is assigned to a certain function group, he
or she can call all function modules that belong to this function group.

In addition to the function groups belonging to the application function modules, authorization object S_RFC must also contain any RFC function groups in order to perform technical processes during communication:
○ for tRFC and qRFC calls between two SAP systems: function groups ERFC and ARFC
○ for all RFC calls in external (non-SAP) systems: function group SYST
You can find an
overview of other authorization objects in the RFC environment in the
RFC Security
Guide, under: