Apache Kafka is widely used as a central platform for streaming data. Yet, previous to 0.9, Kafka had no built-in security features. The 0.9 release of Apache Kafka adds new security features to Kafka:
Administrators can require client authentication using either Kerberos or Transport Layer Security (TLS) client certificates, so that Kafka brokers know who is making each request
A Unix-like permissions system can be used to control which users can access which data.
Network communication can be encrypted, allowing messages to be securely sent across untrusted networks.
Administrators can require authentication for communication between Kafka brokers and ZooKeeper.
For more details, see Apache Kafka Security 101.