IoTHub uses in general (with some iot specific improvements) messaging technology behind Azure Service Bus. That means that connection strings of IoTHub are same or similar as in a case of service bus.
For example, if you open up azure management portal, you can grab the connection string:
However these connection strings are not device specific connection strings. IoTHub connection string can optionally contain a DeviceId token in the string itself. Following snippet shows connection string with device id:
When copying the string from portal, you can append device id to connection string. Another (easier) option is to obtain the connection string from device explorer as shown at the following picture.
Feb 16 2016, 07:07 AM