Besides the above mentioned ODBC protocol there may be database vendor specific standard delivered extraction protocols. Many SAP installations are on Oracle or Hana. Each have their own ports and protocols. Typical SAP databases are in the very back; by far not all ports will be enabled or accessible. The choices are likely going to be limited to what network security will allow.
First find out what the database the source SAP installation is running on: in SAPgui then use System menu -> Status.
