起因
系统扫描报Jetty漏洞，很奇怪，系统中明明没有使用Jetty! 后来发现是Zookeeper中会使用Jetty，因为有使用Kafka，所以也使用了Zookeeper。
Zookeeper使用Jetty主要干2个事情：
1）提供给Prometheus用来输出监控指标用，占用端口7000
2）提供给AdminServer用来查询系统配置项，占用端口8080
也就是说，只要禁用这两个功能就可以了。
1）禁用7000端口
看下官方文档的描述：
Since 3.6.0 ZooKeeper binary package bundles an integration with Prometheus.io
metricsProvider.className : Set to “org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider” to enable Prometheus.io exporter.
metricsProvider.httpHost : New in 3.8.0: Prometheus.io exporter will start a Jetty server and listen this address, default is “0.0.0.0”
metricsProvider.httpPort : Prometheus.io exporter will start a Jetty server and bind to this port, it defaults to 7000. Prometheus end point will be http://hostname:httPort/metrics.
metricsProvider.exportJvmInfo : If this property is set to true Prometheus.io will export useful metrics about the JVM. The default is true.
metricsProvider.numWorkerThreads : New in 3.7.1: Number of worker threads for reporting Prometheus summary metrics. Default value is 1. If the number is less than 1, the main thread will be used.
metricsProvider.maxQueueSize : New in 3.7.1: The max queue size for Prometheus summary metrics reporting task. Default value is 1000000.
metricsProvider.workerShutdownTimeoutMs : New in 3.7.1: The timeout in ms for Prometheus worker threads shutdown. Default value is 1000ms.
在3.8.1版本中，7000端口默认就没打开，所以啥也不用动
#metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
#metricsProvider.httpHost=0.0.0.0
#metricsProvider.httpPort=7000
#metricsProvider.exportJvmInfo=true
也就是说，只要注释掉metricsProvider相关配置即可。
2）禁用8080
还是看下官方文档：
New in 3.5.0: The following options are used to configure the AdminServer.
admin.enableServer : (Java system property: zookeeper.admin.enableServer) Set to “false” to disable the AdminServer. By default the AdminServer is enabled.
admin.serverAddress : (Java system property: zookeeper.admin.serverAddress) The address the embedded Jetty server listens on. Defaults to 0.0.0.0.
admin.serverPort : (Java system property: zookeeper.admin.serverPort) The port the embedded Jetty server listens on. Defaults to 8080.
admin.idleTimeout : (Java system property: zookeeper.admin.idleTimeout) Set the maximum idle time in milliseconds that a connection can wait before sending or receiving data. Defaults to 30000 ms.
admin.commandURL : (Java system property: zookeeper.admin.commandURL) The URL for listing and issuing commands relative to the root URL. Defaults to “/commands”.
默认AdminServer是打开的，我们可以打开访问http://192.168.200.128:8080/commands这个url看下这个界面：
点击比如“configuration”：
这个功能是可以禁用的，只需要在配置文件中设置admin.enableServer=false或者在zkServer.sh中设置java系统变量-Dzookeeper.admin.enableServer=fasle就可以了。
3）禁用JMX端口
禁用了7000和8080以后，发现Zookeeper除了占用2181之外，还占用了一个随机的端口，这个又是干啥的，如下：
[root@localhost apache-zookeeper-3.8.1-bin]# netstat -nap | grep 15216
tcp6 0 0 :::2181 :::* LISTEN 15216/java
tcp6 0 0 :::41897 :::* LISTEN 15216/java
原来是JMX占用的，而且默认也是打开的，可以修改zkServer.sh禁用掉JMX：
# 在最开始添加上这一行即可
export JMXDISABLE=true
