This is related to another config "listener.security.protocol.map" (since version 0.10.2.0). The CLIENT, PLAINTEXT, etc are defined as a name-protocol mapping. So what you have in the listeners property (e.g. CLIENT) must have an entry in the protocol map which determines which protocol to use (e.g. CLIENT:SASL_PLAINTEXT).
The idea is that the same protocol can be used in multiple listeners. For example you might have SASL/SSL in two listeners (different network interface or port). This is part of KIP-103, you can see more details there: https://cwiki.apache.org/confluence/display/KAFKA/KIP-103%3A+Separation+of+Internal+and+External+traffic On Fri, Nov 10, 2017 at 10:10 AM, Thomas Stringer <trstrin...@gmail.com> wrote: > I've been working with Kafka broker listeners and I'm curious is there > any documentation that explains what all of them apply to? Such as > CLIENT, PLAINTEXT, SASL/SSL, etc. I see the encryption part of the > documentation, but is it just inferred what these listeners apply to? > > Thank you in advance! > -- Kaufman Ng +1 646 961 8063 Solutions Architect | Confluent | www.confluent.io