This is a quick post to summarize options to download Oracle Linux installation media ISO images.
To download Oracle Linux 7.5 to install it on a server, virtual or otherwise:
1. Go to Oracle Software Delivery Cloud
2. Sign in using your Oracle account
3. Choose Release from the select list
4. Search for Oracle Linux
5. Choose a release, e.g. 188.8.131.52.0
6. Click the shopping cart icon
7. Click Continue
8. Review and Accept the license agreement
9. Click the link for the file: Oracle Linux Release 7 Update 5 for x86 (64 bit)
This is the only file you need if you simply want to install Oracle Linux 7.5. For more information about the different ISO images, see the documentation: Obtaining and Preparing Installation Media
As Oracle Linux installation media can freely downloaded and re-distributed, there are several download mirrors made available available by third parties, including kernel.org. For a more comprehensive list of download mirrors, see the following article on the Oracle Development Community: Downloading Oracle Linux.
To download Oracle Linux source code, use steps similar to the ones at the top of this post to grab the source DVD ISOs. Alternatively, you can find source RPMs on oss.oracle.com/sources