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 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.
For more information on these parameters see the section “Network communications parameters” in Chapter 4, “Connection and Communication Parameters,” in the Sybase IQ System Administration Guide.
In the following 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)
