monline

First of all, where to find JConsole: it's part of Sun's JDK. Both the Windows and the Linux versions of Sun's JDK (not JRE!) contain JConsole, so it's quite trivial to get. Second: enable JMX remote connections in your Tomcat. If you're running Tomcat on a Debian or Ubuntu server, then you've to add the required startup parameters to the /etc/default/tomcat5.5 file to the CATALINA_OPTS variable. Eg.
(Note: the -Djava.awt.headless=true -Xmx128M -server parameters are there by default).

Now start JConsole (if you're using an Ubuntu desktop and installed the sun-java5-jdk package, then you'll find a "Sun Java 5.0 Console" item in your Applications / System Tools menu), select the Remote tab, enter hostname and port number (7091 in the above example) and connect. You might still get connection error though.