This weekend while setting up RRAS as part of a blog post I am working on a blog posting for Cloudservers.com, I had an issue where an L2TP VPN worked from my Windows 8 PC, but not from my Mac. The GUI error was saying that the VPN was inaccessible, and after looking further in Console, I saw this:

raccoon: not acceptable Identity Protection Mode

The resolution was to edit the /etc/racoon/racoon.conf file. To do this, fire up Terminal or any app (I use iTerm2 it’s awesome), switch to su. Enter your password, and then type in “nano /etc/racoon/racoon.conf” and swap the exchange mode setting from aggressive,main to main,aggressive. Both of these entires were in my file, so I just commented out the second entry:

My connection to my Windows Server 2012 L2TP VPN from Mac OSX now works as expected!