According to Technical Note TN2459 from Apple, "macOS High Sierra 10.13 introduces a new feature that requires user approval before loading newly-installed third-party kernel extensions (KEXTs)". Additionally, Technical Note TN2459 from Apple indicates, "this feature enforces that only kernel extensions approved by the user will be loaded on a system".
When a request is made to load a KEXT that the user has not yet approved, the load request is denied and macOS presents the alert with a System Extension Blocked message.
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For users who have installed GlobalProtect, but are unable to connect, the following steps have resolved the issues for most users:
1. After installing GlobalProtect, Open System Preferences and click Security & Privacy.
2. Under the section Allow applications downloaded from, verify you have allow apps downloaded from Mac App Store and identified developers selected.
Users may see a more detailed screen, as in the example below. If you see this screen, verify that you have App Store and identified developers selected.
Verify that the software you are allowing is named where it says "System software from developer…" Here you should see GlobalProtect. Click Allow.
3. Under the General Tab, look for an Allow or Open Anyway button. If you do see this button, click it. Typically a program will not run at all until you have allowed it, but in the case of GlobalProtect software on a Mac, it will run the software before you allow it but it will not connect. Once you allow the software to run you will be prompted for your Auburn credentials and you should receive a Duo Push.
4. Try connecting to the VPN again. If you are still experiencing issues connecting to the GlobalProtect VPN, contact the IT Service Desk at (334) 844-4944.