Issue: After installing Zenmap under Ubuntu; you attempt to launch it from the ‘Applications’ menu, and receive an error that you are running Zenmap as a nonroot user.
Fix: To fix this issue, simply
1. Right-click on the Applications menu and choose ‘Edit Menus’.
2. Right-click on ‘Zenmap’ and choose ‘Properties’.
3. Change to ‘Command’ field to: ‘gksu zenmap %F’.
The ‘gksu’ command can be prefixed to any Gnome launcher to run as a root user.