I have an oracle client which communicates with an Oracle database through a firewall.
I have been asked to limit the number of ports that need to be opened to an absolute minimum.
I think it should be possible to limit the firewall to open port 1521 only, if I also set the USE_SHARED_SOCKET = TRUE setting in the database server’s registry.
Without the USE_SHARED_SOCKET setting, it seems that the Oracle SQLNET client is handed alternate server ports to use after the initial request to the listener on 1521.
This is an existing application, and I don’t want to create havoc if – by setting this parameter – I break database communication in the application.
What – if any – adverse effects could I expect by using USE_SHARED_SOCKET = TRUE?. Is this a recommended firewall strategy? I’ve seen forums mentioning being locked to “dedicated server mode”, but I don’t think I understand if this is relevant.
Apparently Metalink NOTE 124140.1 provides some additional information, but I don’t have access to Metalink.
On platforms and architectures that Oracle redirects connections to different ports (to the best of my knowledge, Windows servers in general and Unix servers for shared server connections), it generally does so for reasons of efficiency. If you set USE_SHARED_SOCKET to TRUE, you create the potential that there will be performance problems because the operating system has to deal with a lot of traffic for a lot of different logical connections on the same port.
Whether the potential performance problems actually affect your application, of course, is something that you’d have to test. The more connections you have, the more network traffic you create, the greater the potential for problems. But the vast majority of applications won’t see any appreciable performance problems.