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TCP 1521

ProtocolTCP
Port1521
LabelsnCUBE License Manager

Synopsis

  • TCP port 1521 is the default port for the Oracle Net Listener (TNS/SQL*Net) used by Oracle Database.
  • Oracle Database installations (8i through 21c/23ai), including engineered systems like Oracle Exadata, expose the listener on 1521.
  • Oracle Real Application Clusters (RAC) commonly use 1521 for SCAN/listener endpoints to route client connections to clustered databases.
  • Client tools and drivers such as SQL*Plus, Oracle SQL Developer, and the Oracle JDBC Thin driver connect to databases via 1521.
  • Managed offerings like Amazon RDS for Oracle and Oracle Database services on Azure typically default to 1521 for listener connections.
  • Enterprise applications running on Oracle (e.g., Oracle E‑Business Suite, PeopleSoft, and SAP deployments using Oracle as the DB) connect to their backend databases over 1521.
  • Security note: Port 1521 is frequently targeted; the TNS Listener “Poison” flaw (CVE-2012-1675) enabled man-in-the-middle/hijacking, and misconfigured/no listener passwords allow service enumeration and abuse.

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