OS: CentOS 6.4 (server)
I have successfully installed (yum install dsc20) the cassandra database layer in my server and can connect to it using the CQL SHel (cqlsh).
Try this.. It worked for me!
Run the following command on your machine where you have DevCenter installed
$> ssh -L 9042:localhost:9042 @ -N
After running this command, it will prompt for password
Now in your DevCenter > Contact Hosts, provide "127.0.0.1" and test connection. Bingo, you see the magic...