FULL PRODUCT VERSION :
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux CentOS-5-64-0 2.6.18-348.el5 #1 SMP Tue Jan 8 17:53:53 EST 2013 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
I run my program with JDK7 on Centos6. I enable JMX using the following options:

/usr/bin/java -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.local.only=true -Djava.rmi.server.useLocalHostname=true -Djava.rmi.server.useCodebaseOnly=true -Dcom.sun.management.jmxremote.port=9123 -Dcom.sun.management.jmxremote.rmi.port=9123

When I check what ports are opened I discover additional random port that not possible to configure:

netstat -plunt | grep java

tcp 0 0 :::41200 :::* LISTEN 13597/java
tcp 0 0 :::9123 :::* LISTEN 13597/java

Additional run:

tcp 0 0 :::58356 :::* LISTEN 13629/java
tcp 0 0 :::9123 :::* LISTEN 13629/java

The port is not being used when connecting with JConsole.

Also, adding of -XX:+DisableAttachMechanism does not close the port:

/usr/bin/java -XX:+DisableAttachMechanism -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.local.only=true -Djava.rmi.server.useLocalHostname=true -Djava.rmi.server.useCodebaseOnly=true -Dcom.sun.management.jmxremote.port=9123 -Dcom.sun.management.jmxremote.rmi.port=9123



STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Configure JMX using these options:

/usr/bin/java -XX:+DisableAttachMechanism -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.local.only=true -Djava.rmi.server.useLocalHostname=true -Djava.rmi.server.useCodebaseOnly=true -Dcom.sun.management.jmxremote.port=9123 -Dcom.sun.management.jmxremote.rmi.port=9123

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Only one port 9123 is opened
ACTUAL -
Additional random port is opened

REPRODUCIBILITY :
This bug can be reproduced always.