Oracle Community Network
Where can I download old versions of Oracle database, specifically 8.1.7
I need the 8.1.7 client for linux, if it exists.
I know it's ancient, but I am supporting legacy systems.
Oracle don't make them available. In fact, you can't even get 10.2 and 11.1 without a valid (paid-up) licence. See here for details.
Assuming you have a valid support contract, you can log a service request on Metalink and Oracle will provide you with whatever ancient software you need. Oracle doesn't make older versions of software available for public download.