Problem:
Can the InterBase server service be configured to listen to another port other 
than 3050? 

By default, the protocol by which the InterBase client communicates with the 
server is on port 3050.

InterBase and InterClient are officially registered on ports 3050 and 3060 
with IANA (Internet Assigned Numbers Authority). 


Solution:
The information in this article applies to:
* All InterBase versions

Note: Using InterBase with another port other than officially registered ports 
is not an InterBase certified procedure.

The mapping between the service name and the service number can be configured 
on different ports in the services file. 

On Windows NT, this file is in C:windowssystem32driversetcservices.
On Windows 95/98, this file is in C:windowsservices.
On UNIX, this file is in /etc/services.

gds_db		3050/tcp 

The InterBase service name gds_db maps to the port number 3050. You may assign
the gds_db entry service to another port number. It is important to change 
the port number in the services file on all clients and servers which you 
intend connect to.