I just tried upgrading from the version fedora core 2 is distributed with to 184.108.40.206. Before the upgrade the program worked perfectly, after the install, i get the same error that ludetc is getting ("No Connection Provider") suddenly.
Try to see if there are any .tora-files present in your HOME directory by issuing something like "ls -alrt |grep tora".
If ".tora" and ".tora.tse" are present then delete them and try the "tora" command again. Tora crashed the first time, but runs nicely afterwards.
I'm running Oracle Server 10.1.0.3 on Fedora Core 2.