I am having the exact same issue. I executed the egrep command Rahman mentioned. However I could not determine the result based on the print outs. The result did mention that tcp between sandbox.hortonworks.c:60000 and sandbox.hortonworks.c:40993 established. Running the command to find out HBase master address seems failed with SLF4j print out (class path contains multiple SLF4j bindings).
I am using Hortonworks Sandbox 2.0