Hi Aurora,
Apart from the Tomcat port and DB port, you can optionally check the ports in server.xml such as 8009, 8443 in case they're used only. They should not conflict with other applications (sometimes Clarity has 8009 in the properties by default).
And lastly for RMI if used, you need Multicast UDP 4446, and two ports for the cache: 40011 and 40012. Those are configured in the ehcache.xml file, those are the default values.
Opening the ports above should be sufficient for the install.
For example on my test machines I open only Tomcat and DB port and it works great.
Please let us know how it went.
Regards
Nika