DESCRIPTION:
After enabling client DPI-SSL on the SonicWall it is necessary to install the DPI-SSL client certificate on all Macs to avoid the security error presented by installed applications.
- Now open the Keychain Access application on the Mac (Found under Applications | Utilities, alternatively search via Spotlight)
- In the Keychain Access window, click on the System Keychain in the keychain list (top left)
- At the bottom of the window, click on the + button
- Select the certificate downloaded in step 4 and click open to import it
- Select the newly imported certificate (SonicWALL Firewall DPI-SSL) and click on the "i" button
- In the information window, expand the Trust section by clicking on the triangle icon to the left of Trust
- Switch Secure Sockets Layer (SSL) to Always Trust
- Close the information window to save the changes
Referenced from URL: https://www.sonicwall.com/support/knowledge-base/how-to-import-the-dpi-ssl-client-certificate-under-macos/170925061136399/