Develop Reference

Unable to connect remote Java Application from Java VisualVM using JMX

This question has been answered multiple times in Stackoverflow. However, I observe something, that is weird to me.
As the title says, I'm unable to connect to a remote Java application from Java VisualVM from my laptop using JMX.
JVM Arguments used:
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=9701
-Dcom.sun.management.jmxremote.local.only=false
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false
-Djava.rmi.server.hostname=170.76.90.68
Argument provided in "Add JMX Connection" dialogue box":
service:jmx:rmi:///jndi/rmi://170.76.90.68:9701/jmxrmi
I do see an 'established' connection in the remote server. That proves there is no firewall issue.
[09:45:59] dev#mx501:[/home/dex/bin]$ netstat -nap | grep :9701
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 0.0.0.0:9701 0.0.0.0:* LISTEN -
tcp 0 0 170.76.90.68:9701 10.119.136.76:59186 ESTABLISHED -
However, that 'established' connection goes away after some time and I get a typical exception in Java VisualVM, saying the connection could not be established.
[09:56:39] dev#mx501:[/home/dex/bin]$ netstat -nap | grep :9701
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 0.0.0.0:9701 0.0.0.0:* LISTEN -
[09:56:54] dev#mx501:[/home/dex/bin]$
Please help.

How can i connect with jconsole to ActiveMQ jmx?

I try configure jmx according this instruction: http://activemq.apache.org/jmx.html
On localhost all works well. But when i try connect to FreeBSD server over VPN jconsole can't establish connection.
I use such settings for ACTIVEMQ_SUNJMX_START variable:
ACTIVEMQ_SUNJMX_START="
-Dcom.sun.management.jmxremote.port=1616
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.password.file=${ACTIVEMQ_BASE}/conf/jmx.password
-Dcom.sun.management.jmxremote.access.file=${ACTIVEMQ_BASE}/conf/jmx.access
-Djava.rmi.server.hostname=vpn_id_address
-Dcom.sun.management.jmxremote.local.only=false"
What i do wrong?

Confirm the port is listening, using netstat or other tool.
netstat -na | grep 1616
... should show an entry as LISTENING
Try to telnet to the port and send garbage. The server will disconnect you
$ telnet localhost 1099
Trying ::1...
Connected to localhost.
Escape character is '^]'.
garbage
Connection closed by foreign host.
There are a million other reasons why it may not be working. Firewall settings on the server, VPN port mapping, etc.. etc.. Until #1 and #2 are confirmed there isn't anything else to go on.

open command prompt/terminal then type: jconsole
then your jconsole will open and connect to activemq from it
service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi

How to connect to Java instances running on EC2 using JMX

We are having problem connecting to our Java applications running in Amazon's EC2 cluster. We definitely have allowed both the "JMX port" (which is usually the RMI registry port) and the server port (which does most of the work) to the security-group for the instances in question. Jconsole connects but seems to hang and never show any information.
We are running our java with something like the following:
java -server -jar foo.jar other parameters here > java.log 2>&1
We have tried:
Telnets to the ports connect but no information is displayed.
We can run jconsole on the instance itself using remote-X11 over ssh and it connects and shows information. So the JRE is exporting it locally.
Opening all ports in the security group. Weeee.
Using tcpdump to make sure the traffic is not going to other ports.
Simulating it locally. We can always connect to our local JREs or those running elsewhere on our network using the same application parameters.
java -version outputs:
OpenJDK Runtime Environment (IcedTea6 1.11.5) (amazon-53.1.11.5.47.amzn1-x86_64)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
As an aside, we are using my Simple JMX package which allows us to set both the RMI registry and server ports which are typically semi-randomly chosen by the RMI registry. You can also force this with something like the following JMX URI:
service:jmx:rmi://localhost:" + serverPort + "/jndi/rmi://:" + registryPort + "/jmxrmi"
These days we use the same port for both the server and the registry. In the past we have used X as the registry-port and X+1 for the server-port to make the security-group rules easy. You connect to the registry-port in jconsole or whatever JMX client you are using.

We are having problem connecting to our Java applications running in Amazon's EC2 cluster.
It turns out that the problem was a combination of two missing settings. The first forces the JRE to prefer ipv4 and not v6. This was necessary (I guess) since we are trying to connect to it via a v4 address:
-Djava.net.preferIPv4Stack=true
The real blocker was the fact that JMX works by first contacting the RMI port which responds with the hostname and port for the JMX client to connect. With no additional settings it will use the local IP of the box which is a 10.X.X.X virtual address which a remote client cannot route to. We needed to add the following setting which is the external hostname or IP of the server -- in this case it is the elastic hostname of the server.
-Djava.rmi.server.hostname=ec2-107-X-X-X.compute-1.amazonaws.com
The trick, if you are trying to automate your EC2 instances (and why the hell would you not), is how to find this address at runtime. To do that you need to put something like the following in our application boot script:
# get our _external_ hostname
RMI_HOST=`wget -q -O - http://169.254.169.254/latest/meta-data/public-hostname`
...
java -server \
-Djava.net.preferIPv4Stack=true -Djava.rmi.server.hostname=$RMI_HOST \
-jar foo.jar other parameters here > java.log 2>&1
The mysterious 169.254.169.254 IP in the wget command above provides information that the EC2 instance can request about itself. I'm disappointed that this does not include tags which are only available in an authenticated call.
I initially was using the extern ipv4 address but it looks like the JDK tries to make a connection to the server-port when it starts up. If it uses the external IP then this was slowing our application boot time until that timed out. The public-hostname resolves locally to the 10-net address and to the public-ipv4 externally. So the application now is starting fast and JMX clients still work. Woo hoo!
Hope this helps someone else. Cost me 3 hours today.
To force your JMX server to start the server and the RMI registry on designated ports so you can block them in the EC2 Security Groups, see this answer:
How to close rmiregistry running on particular port?
Edit:
We just had this problem re-occur. It seems that the Java JMX code is doing some hostname lookups on the hostname of the box and using them to try to connect and verify the JMX connection.
The issue seems to be a requirement that the local hostname of the box should resolve to the local-ip of the box. For example, if your /etc/sysconfig/network has HOSTNAME=server1.foobar.com then if you do a DNS lookup on server1.foobar.com, you should get to the 10-NET virtual address. We were generating our own /etc/hosts file and the hostname of the local host was missing from the file. This caused our applications to either pause on startup or not startup at all.
Lastly
One way to simplify your JMX creation is to use my SimpleJMX package.

Per the second answer Why does JMX connection to Amazon EC2 fail?, the difficulty here is that by default the RMI port is selected at random, and clients need access to both the JMX and RMI ports. If you're running jdk7u4 or later, the RMI port can be specified via an app property. Starting my server with the following JMX settings worked for me:
Without authentication:
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=9999
-Dcom.sun.management.jmxremote.rmi.port=9998
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
-Djava.rmi.server.hostname=<public EC2 hostname>
With authentication:
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=9999
-Dcom.sun.management.jmxremote.rmi.port=9998
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=true
-Dcom.sun.management.jmxremote.password.file=/path/to/jmxremote.password
-Djava.rmi.server.hostname=<public EC2 hostname>
I also opened ports 9998-9999 in the EC2 security group for my instance.

A bit different approach by using ssh tunnels
(On the Remote machine) Pass the following flags to the JVM
-Dcom.sun.management.jmxremote.port=1099
-Djava.net.preferIPv4Stack=true
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
-Djava.rmi.server.hostname=127.0.0.1
(On the Remote machine) Check which ports java started to use
$ netstat -tulpn | grep java
tcp 0 0 0.0.0.0:37484 0.0.0.0:* LISTEN 2904/java
tcp 0 0 0.0.0.0:1099 0.0.0.0:* LISTEN 2904/java
tcp 0 0 0.0.0.0:45828 0.0.0.0:* LISTEN 2904/java
(On the local machine) Make ssh tunnels for all the ports
ssh -N -L 1099:127.0.0.1:1099 ubuntu#<ec2_ip>
ssh -N -L 37484:127.0.0.1:37484 ubuntu#<ec2_ip>
ssh -N -L 45828:127.0.0.1:45828 ubuntu#<ec2_ip>`
(On the local machine) Connect by Java Mission Control to localhost:1099

The answer given by Gray worked for me, however I find that I have to open TCP ports 0 to 65535 or I don't get in. I think that you can connect on the main JMX port, and then get another one assigned. I got that from this blog post that has always worked well for me.

We are using AWS Elastic Container Service for running our spring boot services.
The below config allowed us to connect to our docker containers.
Without Authentication:
-Dcom.sun.management.jmxremote \
-Dcom.sun.management.jmxremote.port=9090 \
-Dcom.sun.management.jmxremote.rmi.port=9090 \
-Dcom.sun.management.jmxremote.authenticate=false \
-Dcom.sun.management.jmxremote.ssl=false \
-Djava.rmi.server.hostname=$(/usr/bin/curl -s --connect-timeout 2 \
http://169.254.169.254/latest/meta-data/public-ipv4)
I found it crisp and also doesn't require any other servicer side init script.

eclipse: remote debugging a tomcat server behind a firewall

After starting tomcat with jpda on, while at my company I can remote debug a bunch of web applications in eclipse. For a number of reasons I am now in need of developing and remote debugging those same webapps from outside the company firewall, and i can only access that server via ssh on port 22.
I tunneled most needed ports (svn, nexus, tomcat itself, from the server or via the server) to localhost and those services work fine, but I cannot start the eclipse debugger in any way; i'm getting "connection timed out while waiting for packet XXX" or "connection refused" from the second time i try on.
Checking with nmap on the server, it reports the port open before the first connection attempt, and it becomes closed after that. I get no interesting output log in catalina.out
The command i use to start the tunnel is:
ssh -L 8000:localhost:8000 user#mycompany.com
iptables was temporarily stopped both on the server and in the local machine for testing.
Am i missing something? Do I need to forward some other port to localhost? Or is it in some way involved name resolution?
EDIT
Open ports before connection attemp from eclipse:
root#lnxulisse:/opt/apache-tomcat-6.0.32/bin# lsof -p 2147 -n |grep TCP
java 2147 root 4u IPv4 640850 0t0 TCP *:8000 (LISTEN)
java 2147 root 38u IPv6 640859 0t0 TCP *:http-alt (LISTEN)
java 2147 root 40u IPv6 640865 0t0 TCP *:https (LISTEN)
java 2147 root 46u IPv6 640908 0t0 TCP 127.0.0.1:18005 (LISTEN)
java 2147 root 48r IPv6 642625 0t0 TCP 172.24.0.82:48347->172.24.0.82:mysql (ESTABLISHED)
java 2147 root 181u IPv6 640891 0t0 TCP 172.24.0.82:60353->172.24.0.82:mysql (ESTABLISHED)
and after:
java 2147 root 4u IPv6 642769 0t0 TCP 172.24.0.82:48956->172.24.0.82:mysql (ESTABLISHED)
java 2147 root 5u IPv4 640851 0t0 TCP 127.0.0.1:8000->127.0.0.1:34193 (ESTABLISHED)
java 2147 root 38u IPv6 640859 0t0 TCP *:http-alt (LISTEN)
java 2147 root 40u IPv6 640865 0t0 TCP *:https (LISTEN)
java 2147 root 46u IPv6 640908 0t0 TCP 127.0.0.1:18005 (LISTEN)
java 2147 root 181u IPv6 640891 0t0 TCP 172.24.0.82:60353->172.24.0.82:mysql (ESTABLISHED)
exact eclipse error returned is:
Exception occurred during launch
Failed to connect to remote JVM. Connection timed out.
Timeout occurred while waiting for packet 204.
(the packet number varies on each attempt).
in workspace/.metadata/.log i get:
!ENTRY org.eclipse.osgi 2 0 2011-07-17 18:43:53.024
!MESSAGE While loading class "org.eclipse.core.net.proxy.IProxyService", thread "Thread[main,6,main]" timed out waiting (5000ms) for thread "Thread[Thread-6,5,main]" to finish starting bundle "org.eclipse.core.net_1.2.1.r35x_20090812-1200 [232]". To avoid deadlock, thread "Thread[main,6,main]" is proceeding but "org.eclipse.core.net.proxy.IProxyService" may not be fully initialized.
!STACK 0
org.osgi.framework.BundleException: State change in progress for bundle "reference:file:plugins/org.eclipse.core.net_1.2.1.r35x_20090812-1200.jar" by thread "Thread-6".
at org.eclipse.osgi.framework.internal.core.AbstractBundle.beginStateChange(AbstractBundle.java:1073)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:278)
[...]
!ENTRY org.eclipse.ui.ide 4 4 2011-07-17 18:43:53.028
!MESSAGE Proxy service could not be found.
eclipse is configured for direct internet connection.
EDIT 2
I think the solution might be here:
http://blog.cantremember.com/debugging-with-jconsole-jmx-ssh-tunnels/
but i have some trouble understanding his JNDI/RMI settings, and to what extent that applies to my configuration.
EDIT 3
This is a clarification for those answering "use <lan|local ip address> instead of <localhost>"
computer A: my workstation in the company
computer B: my workstation at home
computer C: server running tomcat
B and C are in two different sub-networks in the same network infrastructure; only connections to port 22 of C from outside are allowed (and somewhat "proxied", I don't know network internals).
A is "outside" (my dsl connection with dynamic ip address).
Debugging on C from B via ssh tunnel -> works
Debugging on C from A via ssh tunnel -> connection timed out while waiting for packet XXX

This article suggests that the default port on which the remote Java virtual machine (JVM) is listening in debugging mode is 1044. You should tunnel the port on which the remote JVM is running as well.
More generally, you could run wireshark/tcpdump to see to which port connection attempts are made when starting the debugger.
EDIT:
A few more things I would try:
check on the remote host (e.g. with ps auxwww if it's Linux) with which arguments (look for what comes behind -Xrunjdwp or with lsof -p PID_OF_JVM_TO_BE_DEBUGGED on which TCP port it listens (look for lines with TCP and LISTEN in the lsof output)
make sure that the JVM on the remote host listens on the lo interface, not the network interface (that's what you specify with the localhost in the -L option to ssh).
Does starting the debugger by hand on the machine where you start eclipse with jdb -attach localhost:8000 work ? (you could also try this on the remote host to ensure the debugger is running on the port 8000)
make sure that eclipse tries to connect to localhost (when not specifying a bind address before the first 8000 with the -L option ssh listens on the lo interface)

I often had this problem when doing remote debugging. I do not know the exact reason for this problem, but I used the below solution and maybe it works for you, too:
instead of
ssh -L 8000:localhost:8000 user#remotehost
is used
ssh -L 8000:remotehost:8000 user#remotehost
for creating the SSH tunnel (note the remotehost instead of localhost between the port numbers in the second example). Instead of the remote host's name, you can also use the normal IP address of the remote host (not the loopback address 127.0.0.1, but the true local network IP address).
Hope it helps and good luck!

Assuming the remote Tomcat instance has been started with something like -Xrunjdwp:transport=dt_socket,server=y,address=8000,suspend=n, try this command:
ssh -L 8000:0.0.0.0:8000 user#mycompany.com -N
On my Mac, I tried out ssh -L 10701:localhost:10700 user#localhost -N locally, where a Tomcat instance was started with -Xrunjdwp:transport=dt_socket,server=y,address=10700,suspend=n, and attempting to attach on port 10701 within Eclipse, I kept seeing "Failed to connect to remote VM com.sun.jdi.connect.spi.ClosedConnectionException". By changing the tunnel command to ssh -L 10701:0.0.0.0:10700 user#localhost -N, Eclipse was able to attach.

Can you please give the exact parameters of the -Xrunjdwp parameter?
Also do you have tried different methods for debugging (server=y/n, suspend=y/n)?
Perhaps inversing the connection (let the tomcat connect to the debugger instead of letting the debugger connect to tomcat) may help.

Well I am answering myself after a long time; in my specific case, the solution was to put eclipse JVM in listening mode:
Connection Type: "Standard (Socket Listen)"
and reverse the direction of the tunnel:
ssh -L 8001:localhost:8001 user#work (run on server (S), "localhost" is W)
ssh -R 8001:localhost:8001 user#work (run at home (H), "localhost" is W)
Some explanation: as in the question, my situation was:
H -------------------> S not working ( ssh -L 8001:S:8001 user#S from H)
H W -------> S working ( ssh -L 8001:S:8001 user#S from W)
home work server
While reversing like this:
H <------- W S ssh -R 8001:localhost:8001 user#W (from H)
H W <------- S ssh -L 8001:localhost:8001 user#W (from S)
home work server
did the trick. In other words, whatever is written on S:8001, is forwarded to W:8001, and whatever in turn is written to W:8001, is forwarded to H:8001, where my eclipse JVM is listening.
The tomcat JVM on S should be started with server=n, with arguments:
-agentlib:jdwp=transport=dt_socket,server=n,suspend=n,address=8001

Unable to connect to a remote JVM

I'm working on a Java 10 application that uses an embedded Jetty server to provide control from a local network, and I'm attempting to connect to the JVM and failing. It's running on Ubuntu 18.04 LTS desktop.
My startup script has the following lines:
java -Xdebug -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n -Djava.library_path=${LIB_PATH} -classpath ${CP} -jar ${APP_DIR}/app.jar
I have ufw on the system, and I've verified that the port is open. My output from ufw status includes:
8000 ALLOW Anywhere
8000 (v6) ALLOW Anywhere
In IntelliJ, my debug configuration is
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:8000
When I try to connect, I get an error message that the connection is refused.
with the IP of the machine in the config's address box.
Looking at the output of netstat -l, I see the following:
tcp 0 0 localhost:8000 0.0.0.0:* LISTEN
Does this mean that the debugger is only listening for connection on the localhost? Do I need to do something to have it listen on a network?

So I found the answer fairly quick. I needed to modify the line I use for the server so that it reads:
java -Xdebug -agentlib:jdwp=transport=dt_socket,address=*:8000,server=y,suspend=n -Djava.library_path=${LIB_PATH} -classpath ${CP} -jar ${APP_DIR}/app.jar
So that is listens on all interfaces.