Connecting Across a Firewall

Set the CommLinks connection parameters in your application's connection string to connect across a firewall.

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.

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.
Specify the port your database server is using in the ServerPort parameter if it is not using the default port of 2638. You can use the short form Port.
Set the DoBroadcast=NONE parameter to prevent UDP from being used when connecting to the server.

In this example, the connection string fragment:

Restricts the client application to ports 5050 through 5060
Connects to a server named myeng running on the machine at address myhost using the server port 2020

No UDP broadcast is carried out because of the DoBroadcast option.

CEng=myeng;Links=tcpip(ClientPort=5050–
5060;Host=myhost;Port=2020;DoBroadcast=NONE)

Additional Information

Administration: Database > Connection and Communication Parameters.