我们kafka由公网的许多设备上报信息，服务端的服务来处理，所以要求能通过公网访问，而且内网间不走公网访问来节省流量。下面是一个可用的server.properties:
broker.id=0
num.network.threads=3
num.io.threads=8
socket.send.buffer.bytes=102400
socket.receive.buffer.bytes=102400
socket.request.max.bytes=104857600
log.dirs=/data/kafka
num.partitions=1
num.recovery.threads.per.data.dir=1
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1
log.retention.hours=360
log.retention.check.interval.ms=300000
zookeeper.connect=localhost:2181
zookeeper.connection.timeout.ms=18000
group.initial.rebalance.delay.ms=0
listener.security.protocol.map=INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
listeners=INTERNAL://192.168.1.210:19092,EXTERNAL://192.168.1.210:9092
advertised.listeners=INTERNAL://192.168.1.210:19092,EXTERNAL://48.140.52.103:9092
inter.broker.listener.name=INTERNAL
#super.users=User:admin
#security.inter.broker.protocol=SASL_PLAINTEXT
#sasl.enabled.mechanisms=PLAIN
#sasl.mechanism.inter.broker.protocol=PLAIN
#allow.everyone.if.no.acl.found=true
#authorizer.class.name=kafka.security.authorizer.AclAuthorizer端口直接暴露在公网，但是不加密，这是非常不安全的，所以我们会给它加上密码：
root@robox-middleware:/opt/kafka_2.12-3.5.1/config# cat server.properties
auto.create.topics.enable=false
broker.id=0
num.network.threads=3
num.io.threads=8
socket.send.buffer.bytes=102400
socket.receive.buffer.bytes=102400
socket.request.max.bytes=104857600
log.dirs=/data/kafka
heartbeat.interval.ms=1000
num.partitions=1
num.recovery.threads.per.data.dir=1
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1
log.retention.hours=360
log.retention.check.interval.ms=300000
zookeeper.connect=localhost:2181
zookeeper.connection.timeout.ms=18000
group.initial.rebalance.delay.ms=0
listener.security.protocol.map=INTERNAL:SASL_PLAINTEXT,EXTERNAL:SASL_PLAINTEXT
listeners=INTERNAL://192.168.100.63:19092,EXTERNAL://192.168.100.63:9092
advertised.listeners=INTERNAL://192.168.100.63:19092,EXTERNAL://47.174.123.125:9092
inter.broker.listener.name=INTERNAL
super.users=User:admin
#security.inter.broker.protocol=SASL_PLAINTEXT #这行一定要注释掉
sasl.enabled.mechanisms=PLAIN
sasl.mechanism.inter.broker.protocol=PLAIN
allow.everyone.if.no.acl.found=true
authorizer.class.name=kafka.security.authorizer.AclAuthorizer加上密码的话，需要在config目录写入下面两个配置文件：
#kafka_server_jaas.conf
KafkaServer {
org.apache.kafka.common.security.plain.PlainLoginModule required
username="admin"
password="admin"
user_admin="admin";
};
####
#kafka_client_jaas.conf
KafkaClient {
org.apache.kafka.common.security.plain.PlainLoginModule required
username="admin"
password="admin";
};以上。