The ports Sybase uses are defined in the $SYBASE/interfaces file. An example of the interfaces file is shown below:
master tcp ether hostname 5000
query tcp ether hostname 5000
master tcp ether hostname 5001
query tcp ether hostname 5001
In the above example, the ports 5000 and 5001 are used.
If you need to change these ports, shutdown Sybase, modify the port numbers in the $SYBASE/interfaces file and then start-up Sybase again.