Accessing a Kafka Instance with SASL

If you enable SASL_SSL when creating an instance, data will be encrypted before transmission for enhanced security.

For security purposes, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 is supported.

This section describes how to use an open-source Kafka client to access a Kafka instance if SASL has been enabled for the instance. There are two scenarios. For cross-VPC access, see Cross-VPC Access to a Kafka Instance. For DNAT-based access, see Using DNAT to Access a Kafka Instance.

If intra-VPC plaintext access is enabled for an instance, data is transmitted in plaintext when you connect to the instance through a private network. For details about how to connect, see Accessing a Kafka Instance Without SASL.
Each Kafka broker allows a maximum of 1000 connections from each IP address by default. Excess connections will be rejected. You can change the limit by referring to Modifying Kafka Parameters.

Prerequisites

Security group rules have been correctly configured.
To access a Kafka instance with SASL enabled, configure correct security group rules. For details about security group configuration requirements, see Table 2.
The instance connection address has been obtained.
- For intra-VPC access, use port 9093. Obtain the instance connection address in the Connection section of the Basic Information tab page.
  Figure 1 Kafka instance connection addresses for intra-VPC access with SASL
- For public access, use port 9095. Obtain the instance connection address in the Connection section of the Basic Information tab page.
  Figure 2 Kafka instance connection addresses for public access with SASL
The SASL mechanism in use is known.
In the Connection area on the Kafka instance details page, view SASL Mechanism. If both SCRAM-SHA-512 and PLAIN are enabled, configure either of them for connections. If SASL Mechanism is not displayed, PLAIN is used by default.

Figure 3 SASL mechanism in use
If automatic topic creation is not enabled for the Kafka instance, create a topic before connecting to the instance.
The client.truststore.jks certificate has been downloaded. Click the Kafka instance to go to the Basic Information tab page. Click Download next to SSL Certificate in the Connection area. Download and decompress the package to obtain the client certificate file client.truststore.jks.
Kafka CLI v1.1.0, v2.3.0, or v2.7.2 is available. Ensure that the Kafka instance and the CLI are of the same version.
An ECS has been created. For intra-VPC access, ensure that its VPC, subnet, and security group configurations are the same as those of the Kafka instance. JDK v1.8.111 or later has been installed on the ECS, and the JAVA_HOME and PATH environment variables have been configured as follows:
Add the following lines to the .bash_profile file in the home directory as an authorized user. In this command, /opt/java/jdk1.8.0_151 is the JDK installation path. Change it to the path where you install JDK.
```
export JAVA_HOME=/opt/java/jdk1.8.0_151 
export PATH=$JAVA_HOME/bin:$PATH
```
Run the source .bash_profile command for the modification to take effect.

Accessing the Instance Using CLI

The following uses Linux as an example.

Map hosts to IP addresses in the /etc/hosts file on the host where the client is located, so that the client can quickly parse the instance brokers.

Set IP addresses to the instance connection addresses obtained in Prerequisites. Set hosts to the names of instance hosts. Specify a unique name for each host.

For example:

10.154.48.120 server01

10.154.48.121 server02

10.154.48.122 server03
Decompress the Kafka CLI package.

Access the directory where the CLI package is stored and run the following command to decompress the package:

tar -zxf [kafka_tar]

In the preceding command, [kafka_tar] indicates the name of the CLI package.

For example:

tar -zxf kafka_2.12-2.7.2.tgz
Modify the Kafka CLI configuration file based on the SASL mechanism.
- If PLAIN is used, find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
```
sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=PLAIN

security.protocol=SASL_SSL
ssl.truststore.location={ssl_truststore_path}
ssl.truststore.password=dms@kafka
ssl.endpoint.identification.algorithm=
```
  Parameter description:
  - username and password: username and password you set when enabling SASL_SSL during Kafka instance creation or when creating a SASL_SSL user.
  - ssl.truststore.location: path for storing the client.truststore.jks certificate. Even in Windows, you need to use slashes (/) for the certificate path. Do not use backslashes (\), which are used by default for paths in Windows. Otherwise, the client will fail to obtain the certificate.
  - ssl.truststore.password: server certificate password, which must be set to dms@kafka and cannot be changed.
  - ssl.endpoint.identification.algorithm: whether to verify the certificate domain name. This parameter must be left blank, which indicates disabling domain name verification.
- If SCRAM-SHA-512 is used, find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
```
sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=SCRAM-SHA-512

security.protocol=SASL_SSL
ssl.truststore.location={ssl_truststore_path}
ssl.truststore.password=dms@kafka
ssl.endpoint.identification.algorithm=
```
  Parameter description:
  - username and password: username and password you set when enabling SASL_SSL during Kafka instance creation or when creating a SASL_SSL user.
  - ssl.truststore.location: path for storing the client.truststore.jks certificate. Even in Windows, you need to use slashes (/) for the certificate path. Do not use backslashes (\), which are used by default for paths in Windows. Otherwise, the client will fail to obtain the certificate.
  - ssl.truststore.password: server certificate password, which must be set to dms@kafka and cannot be changed.
  - ssl.endpoint.identification.algorithm: whether to verify the certificate domain name. This parameter must be left blank, which indicates disabling domain name verification.
Access the /bin directory of the Kafka CLI.

In Windows, you need to access the /bin/windows directory.
Run the following command to create messages:
```
./kafka-console-producer.sh --broker-list ${connection-address} --topic ${topic-name} --producer.config ../config/producer.properties
```
Parameter description:
- {connection-address}: the address obtained in Prerequisites. For public access, use Instance Address (Public Network). For intra-VPC access, use Instance Address (Private Network).
- {topic-name}: the name of the topic created for the Kafka instance If automatic topic creation has enabled for the Kafka instance, set this parameter to the name of a created topic or a topic that has not been created.
The following example uses connection addresses 10.3.196.45:9095,10.78.42.127:9095,10.4.49.103:9095.

After running the preceding command, you can send a message to the Kafka instance by writing it and pressing Enter. Each line of content is sent as a message.
```
[root@ecs-kafka bin]#./kafka-console-producer.sh --broker-list 10.3.196.45:9095,10.78.42.127:9095,10.4.49.103:9095  --topic topic-demo --producer.config ../config/producer.properties
>Hello
>DMS
>Kafka!
>^C[root@ecs-kafka bin]# 
```
To stop creating messages, press Ctrl+C to exit.
Run the following command to retrieve messages:
```
./kafka-console-consumer.sh --bootstrap-server ${connection-address} --topic ${topic-name} --group ${consumer-group-name} --from-beginning  --consumer.config ../config/consumer.properties
```
Parameter description:
- {connection-address}: the address obtained in Prerequisites. For public access, use Instance Address (Public Network). For intra-VPC access, use Instance Address (Private Network).
- {topic-name}: the name of the topic created for the Kafka instance
- {consumer-group-name}: the consumer group name set based on your service requirements. If a consumer group name has been specified in the configuration file, ensure that you use the same name in the command line. Otherwise, consumption may fail. If a consumer group name starts with a special character, such as a number sign (#), the monitoring data cannot be displayed.
Example:
```
[root@ecs-kafka bin]#  ./kafka-console-consumer.sh --bootstrap-server 10.3.196.45:9095,10.78.42.127:9095,10.4.49.103:9095 --topic topic-demo --group order-test --from-beginning --consumer.config ../config/consumer.properties
Hello
DMS
Kafka!
^CProcessed a total of 3 messages
[root@ecs-kafka bin]# 
```
To stop retrieving messages, press Ctrl+C to exit.