C clients can use the MQ_SERVICE_PORT_PROPERTY connection property to specify a fixed port to connect to. This can be useful if you're trying to get through a firewall or if you need to bypass the broker's port mapper service (which assigns ports dynamically).
Remember that you need to configure the JMS service port on the broker side as well. For example, if you want to connect your client via ssljms to port 1756, you would do the following.
On the client side: Set the MQ_SERVICE_PORT_PROPERTY to 1756 and set the MQ_CONNECTION_TYPE_PROPERTY to SSL.
On the broker side: Set the imq.serviceNameType.protocol.port property to 1756 as follows.
The MQ_SERVICE_PORT_PROPERTY connection property was introduced with version 3.7 Update 2 of Message Queue.