Our software library provides a free download of Ostiarius 1.2 for Mac. The latest setup file that can be downloaded is 18 KB in size. Our built-in antivirus checked this Mac download and rated it as 100% safe. This free software for Mac OS X was originally produced by Objective-see LLC.
From the developer:
Ostiarius is tool for El Capitan that blocks unsigned internet binaries from executing. With the kernel extension loaded, any unsigned binary or application from the internet will be automatically blocked by Ostiarius. This will happen automatically and transparently.