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Understanding TNS Listener

December 20th, 2006 by Rajender Singh · 5 Comments

I was going through some papers about TNS Listener, so I though why not share what I know and what I learn from it. So here it is.

What is TNS Listener?

TNS (Transparent Network Substrate) Listener is a server process that listen for a database connection request on a specific port (By the default 1521, but can be configured to use other port) on the database server.

How TNS Listener works?

  1. Whenever a connection request with username, password and with particular SID or service name is received on that specific port.
  2. It check the SID or service name and if configured to listen to that SID or service name then forward the login information to that instance or will return an appropriate error message to the requester.
  3. After this database authenticates login information, the listener process redirect the client to any new available port and a session is create between client and the server on that new port.
  4. Once this flow is completed, it again start listening on original port leaving server process and client process to do their own work.

The job of listener is not limited to database connection. It also enable client to access to external procedure (example external programs in c language).


Tags: Oracle Administration · Oracle Database

5 responses so far ↓

  • 1 S. Inderjeet Singh // Dec 21, 2006 at 3:39 pm

    “After this database authenticates login information, the listener process redirect the client to any new available port and a session is create between client and the server on that new port.”

    hi, pls clarify:
    this new port can be which port.

  • 2 S. Inderjeet Singh // Dec 21, 2006 at 3:47 pm

    “After this database authenticates login information, the listener process redirect the client to any new available port and a session is create between client and the server on that new port.”

    hi, pls calrify which port it could be.

  • 3 S. Inderjeet Singh // Dec 21, 2006 at 3:48 pm

    “After this database authenticates login information, the listener process redirect the client to any new available port and a session is create between client and the server on that new port.”

    hi, pls clarify which port it could be.

  • 4 OracleBrains.Com » Blog Archive » Which port - Understanding TNS Listener // Dec 28, 2006 at 10:44 am

    [...] Which port - Understanding TNS Listener   Comment by S. Inderjeet Singh on Understanding TNS Listener [...]

  • 5 OracleBrains Oracle Community Webspace - Blog » Which port - Understanding TNS Listener // Jan 2, 2007 at 12:50 am

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