As of 720 kernel, registration of external server program is controlled by profile parameters gw/acl_mode, gw/reg_info and gw/sec_info.
For security reasons, SAP has made it mandatory to use gw/reg_info and gw/sec_info to allow any external program to get registered on host.
Entries of the hosts wanting to register program in gateway have to be maintained in the file reg_info and sec_info (location of these files is maintained using gw/reg_info and gw/sec_info profile parameter)

All supported platforms

If the files reg_info and sec_info are created without any entries, then no external server is allowed to register external programs thus entries for the servers has to be maintained.

If the files reg_info and sec_info are not created, then parameter gw/acl_mode can be used to control registration of external programs on the system.
gw/acl_mode = 0 will allow registration of external server program
gw/acl_mode = 1 will not allow registration of external server programs and you need to maintain reg_info and sec_info files.

More information about the same can be found in below SAP notes :
Note 1408081 – Basic settings for reg_info and sec_info
Note 1069911 – GW: Changes to the ACL list of the gateway (reginfo)

 

How to resolve "ERROR registration of tp from host ??? not allowed" raised while starting TIBCO ActiveMatrix Adapter for SAP instance

registration of tp <ProgramID> from host ??? not allowed, SAP-Gateway