Unable to connect to SonicWall L2TP VPN’s on Mac OS X High Sierra

We are big fans of SonicWall devices due to their simplicity to manage and maintain for our clients. “Keep It Simple Stupid” has been a mantra we live by throughout our careers. Our clients use multiple devices and operating systems to connect to their networks, and a good network is flexible in handling any device from any connection at any time.

Some clients may want to connect to their corporate networks from a Mac, and a great way to provide this connectivity without using a SSLVPN license is setting up a L2TP VPN server on your SonicWall. The configuration will be discussed in another blog post, so let’s focus on issues you may have with connecting from a Mac.

“Racoon” is the IPSec application on a Mac that allows you to connect to a VPN and I have seen it become corrupted more times than not, usually by a third-party VPN application such as “Shimo”.   The executable is located at: /usr/sbin/racoon

In order to restore this file from a time machine backup, or to replace this file with a known, working copy, you must first boot into single user mode and disable System Integrity Protection which protects critical operating system files from being replaced. Once you have replaced a critical file, you will need to reboot into single user mode and from the terminal re-enable System Integrity Protection to protect your Mac from future attacks.

  1. Reboot your Mac and press and hold the “Command + R” keys to boot your Mac into recovery mode.
  2. From the “Utilities” menu, click “Terminal”
  3. Type the following commands in the terminal window:
    1. csrutil disable
    2. reboot
  4. Your Mac will then boot normally, and from a Time Machine backup or from a known, working copy of “/usr/sbin/racoon” as root, replace the corrupted file and attempt to connect to your L2TP VPN server.
  5. Once you verify success in your connection, reboot back into single user mode and type the following commands in a terminal window:
    1. csrutil enable
    2. reboot

Your Mac will now have System Integrity Protection turned back on to protect your critical system files.

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