The SAP Gateway and the SNC Interface 
Using the SAP interface SNC (Secure Network Communication) guarantees secure communication.
SNC supports third-party security systems (such as Kerberos, SECUDE, etc.). This ensures reliable authentication of the partners and secure data transfer.
The SAP Gateway can reject connections that are not based on SNC.
SAP provides a range of SNC parameters. For more information on configuration see:
Parameterization of the SAP Gateway, SNC parameters
Documentation of parameters that begin with snc (transaction RZ11, AS ABAP only)