There are restrictions on connections when the client application is on one side of a firewall, and the server is on the other. Firewall software filters network packets according to network port. Also, it is common to disallow UDP packets from crossing the firewall.
When connecting across a firewall, you must use a set of communication parameters in the CommLinks connection parameter of your application's connection string.
Set the UseUDP parameter to OFF to prevent UDP packets from being used to locate the server. You can use the short form UDP.
Set the ClientPort parameter to a range of allowed values for the client application to use. You can then configure your firewall to allow these packets across. You can use the short form CPort.
Set the HOST parameter to the host name on which the database server is running. You can use the short form IP.
If your database server is not using the default port of 2638, you must specify the port it is using, in the ServerPort parameter. You can use the short form Port.
For more information on these parameters see the System Administration Guide.
The following connection string fragment restricts the client application to ports 5050 through 5060, disables UDP packets, and connect to a server named myiq running on the machine at address myhost using the server port 2020.
CommLinks=tcpip(UseUDP=OFF;ClientPort=5050-5060;Host=myhost;Port=2020;Eng=myiq)
For more detailed information on networking and protocol stacks, refer to networking-specific documentation.
