How to connect to Oracle 9i through SSH tunnel if TNS protocol issues a REDIRECT to a random port?

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                          Inspecting packets exchanged between SQLDeveloper and Oracle 9i I noticed that, in the beginning of the connection negotiation, the server issues a REDIRECT back to the client, pointing a port different from 1521. The client then connects using this new port. This is apparently a normal behavior of TNS protocol.
Because of this behavior it's difficult to connect remotely via SSH tunnel or through firewalls.

client sends this:

    tns.connect_data = (DESCRIPTION=(CONNECT_DATA=(SID=xyz)(CID=(PROGRAM=SQL Developer)(HOST=__jdbc__)(USER=abc)))(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.100.100)(PORT=1521)))

and receives this:

    tns.redirect_data = (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.100.100)(PORT=1236))

Is there a way to disable this redirect? Or at least limit the redirection to a few known ports?

According to this  there are 2 solutions:

 1. use shared server and configure the dispatchers
 2. use connection manager

Regarding **1. shared servers**, I created a new shared server an tried to configure the dispatchers like this  and this :

    alter system set DISPATCHERS='(PROTOCOL = TCP)(ADDRESS=(PROTOCOL=tcp)(HOST=myHost)(PORT=5000))' scope=spfile sid='xyz';

But I get errors like:

    02065. 00000 -  "illegal option for ALTER SYSTEM" Cause: The option specified for ALTER SYSTEM is not supported
    
Removing the scope and sid:

    00101. 00000 -  "invalid specification for system parameter DISPATCHERS" Cause: The syntax for the DISPATCHERS parameter is incorrect.

removing the (PROTOCOL = TCP):

    00105. 00000 -  "too many dispatcher configurations" Cause: Too many dispatcher configurations have been specified. No more can be added.

Regarding **2. connection manager** I enabled the cman and cman admin services, created cman.ora as:

    cman = (ADDRESS_LIST=
               (ADDRESS=(PROTOCOL=tcp)(HOST=myHost)(PORT=1630)(QUEUESIZE=32))
           )
    
    cman_admin = (ADDRESS=(PROTOCOL=tcp)(HOST=myHost)(PORT=1830))

and followed this . I always get connection refused. I could connect to port 1630, after putting it in the listener. In the end the port redirect still happened.

Asked by Gustavo (173 rep)

Jul 3, 2022, 08:51 PM

How to connect to Oracle 9i through SSH tunnel if TNS protocol issues a REDIRECT to a random port?

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