Connecting remote tomcat JMX instance using jConso

Question

I am trying to connect to a remote tomcat JMX instance using jConsole. But can't connect successfully. Any Idea?

I included the following option in remote tomcat catalina.sh:

JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote \
    -Dcom.sun.management.jmxremote.port=9004 \
    -Dcom.sun.management.jmxremote.ssl=false \
    -Dcom.sun.management.jmxremote.authenticate=false"

Answer 1

What exactly do you mean when you say "But can't connect successfully."? Is there an error message? Try turning on logging in jconsole and see if that helps debug it.

To turn on jconsole logging, edit a file named logging.properties in the directory you will be running jconsole in, add:

handlers= java.util.logging.ConsoleHandler

.level=INFO

java.util.logging.FileHandler.pattern = %h/java%u.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter

java.util.logging.ConsoleHandler.level = FINEST
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

javax.management.level=FINEST
javax.management.remote.level=FINEST

Then, start jconsole with:

jconsole -J-Djava.util.logging.config.file=logging.properties

Answer 2

Check if your server is behind the firewall. JMX is base on RMI, which open two port when it start. One is the register port, default is 1099, and can be specified by the com.sun.management.jmxremote.port option. The other is for data communication, and is random, which is what cause problem. A good news is that, from JDK6, this random port can be specified by the com.sun.management.jmxremote.rmi.port option.

add the line in you {tomcat_dir}/bin/setenv.sh:

export CATALINA_OPTS="-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=8991 -Dcom.sun.management.jmxremote.rmi.port=8991 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false"

Answer 3

Changing the /etc/hosts on linux, where I replaced the localhost address associated to my account to the machine ip, solved this problem for me.

Answer 4

I've collected information spread over the net, found with hints from other members.

Most pain caused by JMX is (imo) the fact that JMX opens a second dynamically allocated network port. A firewall (like iptables) will block this.

Solution for tomcat on linux :

use tomcat 6.0.24 or newer download catalina-jmx-remote.jar from apache tomcat extras (use browse on tomcat download page) copy it in the $CTALINA_HOME\lib

This allows you to set both ports used by JMX

edit Server section in your server.xml

<Server port="8005" ..>
  ...
  <Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener" rmiRegistryPortPlatform="9840" rmiServerPortPlatform="9841"/>

set some environment variables (e.g. in setenv.sh)

CATALINA_OPTS="
  -Djava.rmi.server.hostname=IP-TO-LISTEN
  -Dcom.sun.management.jmxremote.password.file=$CATALINA_BASE/conf/jmxremote.password 
  -Dcom.sun.management.jmxremote.access.file=$CATALINA_BASE/conf/jmxremote.access 
  -Dcom.sun.management.jmxremote.ssl=false"

this activates access control for JMX

jmxremote.access will look like

monitorRole readonly
controlRole readwrite

end jmxremote.password will be

monitorRole tomcat
controlRole tomcat

(just simple spaces)

restart tomcat.

Now configure firewall on the server (e.g. iptables)

/etc/sysconfig/iptables

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 9840 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 9841 -j ACCEPT

and /etc/sysconfig/ip6tables

-A RH-Firewall-1-INPUT -m tcp -p tcp --dport 9840 -j ACCEPT
-A RH-Firewall-1-INPUT -m tcp -p tcp --dport 9841 -j ACCEPT

restart iptables

Done!

Now use VisualVM or JConsole on your workstation to establish a connection to rmiRegistryPortPlatform, 9840 in our sample.

If there are no more firewalls between workstation and server it should work.

Answer 5

what string are you using as the JMX connection url. I don't mean to point out the obvious but JConsole has a terrible interface and to me requires an overly complex url before it will connect to a remote jmx app. Mine looks like this:

service:jmx:rmi:///jndi/rmi://(hostname):(jmxport)/jmxrmi

Answer 6

Well, I had this problem in a Linux box (virtual machine) and I fixed it using -Djava.rmi.server.hostname property but there's a thing I can't understand. My machine has 5 tomcat servers, all of them has jmx enabled in consecutive ports (8008,8018,8028...) and only one of them had this issue connecting JMX. No firewall, no -Djava.rmi.server.hostname property in any tomcat....

So the thing is that I understand the problem but I can't understand why 4 of my tomcats worked and 1 of them not.

P.D: My english is very poor, I know. My Apologies.