setting-up oracle-xe

I开发者_如何转开发 installed oracle-xe into my virtual box that running with Fedora 13 successfully. Although I can ping my virtual machine, I can not connect the database from outside the box. Do I have to make some changes on tnsnames.ora or can I use another connection type for this situation? I would be greatly appreciated if someone be able to give me some tips.

Thanks in advance.