Configuring the Kafka Broker

The Kafka Broker supports listening on multiple ports and IP addresses. To enable this feature, specify one or more comma-separated values in the listeners property in server.properties.

1. Both PLAINTEXT and SSL ports are required if SSL is not enabled for inter-broker communication (see the following subsection for information about enabling inter-broker communication): listeners=PLAINTEXT://host.name:port,SSL://host.name:port.

   The following SSL configuration settings are needed on the broker side:

   ssl.keystore.location = /var/private/ssl/kafka.server.keystore.jks
   ssl.keystore.password = test1234
   ssl.key.password = test1234
   ssl.truststore.location = /var/private/ssl/kafka.server.truststore.jks
   ssl.truststore.password = test1234

   The following optional settings are available:

   Property	Description	Value(s)
   ssl.client.auth	Specify whether client authentication is required, requested, or not required. none: no client authentication. required: client authentication is required. requested: client authentication is requested, but a client without certs can still connect. Note: If you set ssl.client.auth to requested or required, then you must provide a truststore for the Kafka broker. The truststore should contain all CA certificates that are used to sign clients' keys.	none
   ssl.cipher.suites	Specify one or more cipher suites: named combinations of authentication, encryption, MAC and key exchange algorithms used to negotiate the security settings for a network connection using the TLS or SSL network protocol.
   ssl.enabled.protocols	Specify the SSL protocols that you will accept from clients. Note: SSL is deprecated; its use in production is not recommended.	TLSv1.2,TLSv1.1,TLSv1
   ssl.keystore.type	Specify the SSL keystore type.	JKS
   ssl.truststore.type	Specify the SSL truststore type.	JKS

2. To enable SSL for inter-broker communication, add the following setting to the broker properties file (default is PLAINTEXT): security.inter.broker.protocol = SSL.
3. To enable any cipher suites other than the defaults that come with JVM (see “Java Cryptography documentation”), you will need to install JCE Unlimited Strength Policy files (download link below).
4. Validate the configuration. After you start the broker, you should see the following information in the server.log file:

   with addresses: PLAINTEXT -> EndPoint(192.168.64.1,9092,PLAINTEXT),SSL -> EndPoint(192.168.64.1,9093,SSL)

5. To make sure that the server keystore and truststore are set up properly, run the following command:openssl s_client -debug -connect localhost:9093 -tls1.

   (Note: TLSv1, TLSv1.1, and TLSv1.2 should be listed under ssl.enabled.protocols)

   In the openssl output you should see the server certificate; for example:

   Server certificate
   -----BEGIN CERTIFICATE-----
   MIID+DCCAuACCQCx2Rz1tXx3NTANBgkqhkiG9w0BAQsFADB6MQswCQYDVQQGEwJV
   UzELMAkGA1UECAwCQ0ExFDASBgNVBAcMC1NhbnRhIENsYXJhMQwwCgYDVQQKDANv
   cmcxDDAKBgNVBAsMA29yZzEOMAwGA1UEAwwFa2FmYWsxHDAaBgkqhkiG9w0BCQEW
   DXRlc3RAdGVzdC5jb20wHhcNMTUwNzMwMDQyOTMwWhcNMTYwNzI5MDQyOTMwWjBt
   MQswCQYDVQQGEwJVUzELMAkGA1UECBMCQ0ExFDASBgNVBAcTC1NhbnRhIENsYXJh
   MQwwCgYDVQQKEwNvcmcxDDAKBgNVBAsTA29yZzEfMB0GA1UEAxMWU3JpaGFyc2hh
   IENoaW50YWxhcGFuaTCCAbcwggEsBgcqhkjOOAQBMIIBHwKBgQD9f1OBHXUSKVLf
   Spwu7OTn9hG3UjzvRADDHj+AtlEmaUVdQCJR+1k9jVj6v8X1ujD2y5tVbNeBO4Ad
   NG/yZmC3a5lQpaSfn+gEexAiwk+7qdf+t8Yb+DtX58aophUPBPuD9tPFHsMCNVQT
   WhaRMvZ1864rYdcq7/IiAxmd0UgBxwIVAJdgUI8VIwvMspK5gqLrhAvwWBz1AoGB
   APfhoIXWmz3ey7yrXDa4V7l5lK+7+jrqgvlXTAs9B4JnUVlXjrrUWU/mcQcQgYC0
   SRZxI+hMKBYTt88JMozIpuE8FnqLVHyNKOCjrh4rs6Z1kW6jfwv6ITVi8ftiegEk
   O8yk8b6oUZCJqIPf4VrlnwaSi2ZegHtVJWQBTDv+z0kqA4GEAAKBgB+Pdz0306bq
   TpUAdb2FERMPLFsx06H0x+TULivcp7HbS5yrkV9bXZmv/FD98x76QxXrOq1WpQhY
   YDeGDjH+XQkJ6ZxBVBZNJDIpCnfQpfzXAvryQ+cm8oXUsKidtHf4pLMYViXX6BWX
   Oc2hX4rG+lC8/NXW+1zVvCr9To9fngzjMA0GCSqGSIb3DQEBCwUAA4IBAQBfyVse
   RJ+ugiNlWg5trZscqH0tlocbnek4UuV/xis2eAu9l4EFOM5kRt5GmkGZRcM/zHF8
   BRJwXbf0fytMQKSPFk8R4/NGDOlzoK+F7uXeJ0S2u/T29xk0u2i4tjvleq6OCphE
   i9vdjM0E0Whf9SHRhOXirOYFX3cL775XwKdzKKRkk+AszFR+mRu90rdoaepQtgGh
   9Kfwr4+6AU/dPtdGuomtBQqMxCzlrLd8EYhVVQ97wHIZ3sPvlM5PIhOJ/YHSBJIC
   75eo/4acDxZ+j3sR5kcFulzYwFLgDYBaKH/w3mYCgTALeB1zUkX53NVizIvhUd69
   XJO4lDSDtGOlfort
   -----END CERTIFICATE-----
   subject=/C=US/ST=CA/L=Santa Clara/O=org/OU=org/CN=JBrown
   issuer=/C=US/ST=CA/L=Santa Clara/O=org/OU=org/CN=kafak/emailAddress=test@test.com