Using oracle db through ssh tunnel. Error "ORA-12541: TNS:no listener"

Normally this should work. I would not use a default listener port as an entry for the ssh tunnel but that should not be the problem. I would also not user the root account to create the ssh connection, preferably a dedicated regular account. Are you using shared servers or does the database happen to be a RAC database with a load balance configuration? A nice explanation is here How can I connect to ORACLE DB through ssh tunnel chain (double tunnel, server in company network) ?, a bit more complicated .....

update checkout DbVisualizer, it now has integrated ssh tunneling. I think it is worth to al least give it a try. It's not free but good. Multi platform and multi database and very flexible.

Look into Metalink ID 361284.1 (Edit: effectively not public, but find the info here)

It seems like Oracle Connection Manager would be your option. It basically handles the port redirects inside the firewall. I haven't used it before, so cannot advise you further.

---

Update: Another way to go would be to use MTS, configure dispatchers with certain ports and open these ports in the firewall. You wouldn't have to install additional software for this, but connecting through shared server may require increasing LARGE_POOL_SIZE, among other considerations. So you'd still need the DBA role to change the DISPATCHERS parameter. You'd also have to bounce the DB.