How to authenticate with cassandra-stress 2.1
It seems that it's been moved to the -mode option.
Try cassandra-stress -mode user=username password=password.
The correct parameters are:
cassandra-stress [command] -node [nodes] -mode thrift user=[user] password=[password]
thrift is the default protocol, connecting to port 9160 on your nodes. The list of nodes should be separated by commas.