If you have enough disk space, you can also download a repository snapshot, but be advised that this can take up to 20Gb or even more.
How is this repository snapshot obtained? I do not want to mirror. I just want the latest copies of the files from the OpenSUSE 12.3 Update repository to upgrade an offline system.
If you want to, you can access the repos through ftp, download whatever you need into one single folder. Next, on the server, add that folder as a repository (check the “RPM-folder” option).