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javajmxjconsolejvisualvm

Does Java 6 open a default port for JMX remote connections?

My specific question has to do with JMX as used in JDK 1.6: if I am running a Java process using JRE 1.6 with 

com.sun.management.jmxremote

in the command line, does Java pick a default port for remote JMX connections?

Backstory: I am currently trying to develop a procedure to give to a customer that will enable them to connect to one of our processes via JMX from a remote machine. The goal is to facillitate their remote debugging of a situation occurring on a real-time display console. Because of their service level agreement, they are strongly motivated to capture as much data as possible and, if the situation looks too complicated to fix quickly, to restart the display console and allow it to reconnect to the server-side.

I am aware the I could run jconsole on JDK 1.6 processes and jvisualvm on post-JDK 1.6.7 processes given physical access to the console. However, because of the operational requirements and people problems involved, we are strongly motivated to grab the data that we need remotely and get them up and running again.

EDIT: I am aware of the command line port property 

com.sun.management.jmxremote.port=portNum

The question that I am trying to answer is, if you do not set that property at the command line, does Java pick another port for remote monitoring? If so, how could you determine what it might be?

Solution

  • The documentation suggests that the JMX agent uses a local port -- something unreachable from outside the machine -- unless you specify the following property:

    com.sun.management.jmxremote.port=portNum

    This is for security reasons, as well as for the reason given by Mr Potato Head. Thus, it looks like Java 6 does not open a default remotely accessible port for JMX.

    EDIT: Added after the OP added an answer with more information.

    Another option you have is to somehow create a local proxy that listens to all local JMX connections and exports this information. This way, you don't need to have such magic configuration of each JVM instance on the server. Instead the local proxy can connect to all JVMs via JMX and then somehow expose this information remotely. I am not positive exactly how you would implement this, but something like this may be less work than what you otherwise have to do to expose all of your JVMs remotely via JMX.