Internet-Security.com TCP port 446 details

TCP port 446 is the well-known port for IBM Distributed Data Management (DDM) and DRDA remote database access, primarily on IBM i (AS/400) and IBM DB2 for z/OS systems.
Real-world examples include the IBM DB2 for i database host server listening on 446 for DDM/DRDA clients, and the DB2 for z/OS Distributed Data Facility (DDF) being configured to accept DRDA connections on this port.
IBM client software such as IBM i Access Client Solutions, IBM DB2 Connect, and the IBM JCC (JDBC) driver may use port 446 when connecting to those DB2/DRDA services.
In network scans, AS/400/IBM i hosts commonly show 446/tcp as “ddm” or “ddm-rdb,” with the SSL-secured variant typically on port 448.
Outside IBM ecosystems, this port is rarely used.

TCP 446