Under the following directory you will find a file named context.xml:
Edit the file with your favorite text editor and add the following line between "<context>" and "</context>" tags:
<Valve className="org.apache.catalina.valves.RemoteAddrValve" allow="192.168.0.*"/>
Then only hosts in the 192.168.0.0/24 network would get access to ZCC.
After saving the edited file you need to restart ZENworks before the changes take effect.
Disclaimer: As with everything else at Cool Solutions, this content is definitely not supported by Novell (so don't even think of calling Support if you try something and it blows up).
It was contributed by a community member and is published "as is." It seems to have worked for at least one person, and might work for you. But please be sure to test, test, test before you do anything drastic with it.