TCP Parameter in SQLNET file of Oracle

TCP.CONNECT_TIMEOUT:

Parameter value specify the time for a client to establish a TCP connection with the database Server. Default value is 60 seconds.
If connection is not established in specified time then following error occurred:
ORA-12170: TNS:Connect timeout occurred

Example:

TCP.CONNECT_TIMEOUT=30 ms

TCP.VALIDNODE_CHECKING

Valid node checking is used to enable or disable the verify the nodes in incoming connection.
Parameter value is YES, then incoming connections are allowed only if they stasfiy the values of both parameters TCP.INVITED_NODES or
TCP.EXCLUDED_NODES parameters. Default value is NO.
Example in SQLNET.ora file

TCP.VALIDNODE_CHECKING=yes

TCP.INVITED_NODES

In this parameter we specify the value or IP address or Host-name of the client which will allow to make connection with database. Parameter works with validnode_checking value is YES.

Example:

TCP.INVITED_NODES=(ORCL.oracle.com,192.0.*,2321:BD4:3456:566A/32)

Note: Parameter supports IPv4 , IPv6 and wild-cards character for multiple entries

TCP.EXCLUDED_NODES

In this parameter we specify that address which deny access to the database. you can specify host-name and IP address as values. Parameter works with validnode_checking value is YES.

Example:

TCP.EXCLUDED_NODES=(orcl.oracle.com,192.10.10.1,172.10.*,2321:BD4:3456:566A/32)

Note: Parameter supportsvIPv4 , IPv6 and wildcards character for multiple entries