Hi, Sorry to reply to my own topics... I've found how to solve my problem. There is a jndi.properties file in the twiddle.jar file. In the jndi.properties file, I've added the line: jnp.disableDiscovery=true Now when my Jboss server is down, twiddle.sh returns an Exception. I still have to modify the check_jbossjmx nagios script to deal with this exception. Thanks Dimitris for your answer. Bruno View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3989690#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...