Many thanks Noway.
For instance the listener within the Redhat database machine is

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = webserver)(PORT = 1521))
)
)

but through the internet, how can I make the host name of the database "seeable" by other machines? I know that for making one Oracle connection, that HOST should be also "seeable" in my local machine, on which I am using to remotely connect to the database.

Actually I'm fine to ping the IP of the router of the database machine.

If I understand your question correctly, you want to be able to access your Oracle database remotely, from the internet or from a network out side of the LAN on which your database machine sits. I also gather that your database machine is behind a router and that you can successfully ping that router.

In this case, the answer is (typically) quite simple. You need to enable a function called port forwarding on your router. How this is done will be specific to your router, but in essence you specify that connections arriving on the desired port are forwarded to the (LAN) IP address of the desired host machine. To directly allow access to your Oracle database, you would need to forward port 1521.

For security reasons, I would highly suggest that you carefully consider the risks in doing so. At a minimum you should configure your router such that the connections to this port will only be accepted from a known, trusted, host or domain. It would be better, in fact much better, to set up a VPN and obtain a local LAN address and access the database that way. SSH can even be used for this function. The problem is that if you put an Oracle database on the Internet that it will become a big flashing target for attack.

Edit One other thing to consider: I haven't used Oracle, but in other database systems, the authentication is by user@host. When you connect remotely, you may have to adjust the user credentials to allow the remote connection.

1 members found this post helpful.

Good day Noway,
For the VPN, any advice if it's to use the service from
https://www.shieldexchange.com

Honestly, I had never heard of Shield Exchange before. I notice at the bottom of their screen it says powered by OpenVPN. From watching their introduction, it looks more like a proxy service to have internet access from an insecure location, which if I understand your goals is backwards of what you want. However, the link does bring up OpenVPN which would work. Depending on your user requirements it is even free (for two simultaneous users and a block of more is something like $10 USD). There are other software choices based on other technology too. Otherwise, you could use a hardware router with VPN support, like a Cisco to the same effect.

You could also SSH into that local machine, with or without X-forwarding, or even use something like Free-NX for remote desktop too, depending on your needs.

1 members found this post helpful.