I'm not a Mac user. However, recently I had the chance to test the Mac OS X 10.4.8 and Mac OS X 10.4.10 as L2TP/IPsec VPN clients with ISA Server 2006 as L2TP/IPsec VPN server. I've decided to put a couple of notes regarding what I have observed.
In this part we will talk about using certificates for IKE authentication.
In a future part, we will talk about using pre-shared keys. Pre-shared keys are a weak authentication method, but they can be useful for testing.
I do not have currently access to a Mac OS X 10.5.x machine. When/if I will have access to such a machine, I will test to see what happens.
I've started configuring and connecting with a Mac OS X 10.4.8 machine. I thought I got it working, but when I attempted to connect with a Mac OS X 10.4.10 machine, I could not. So I needed to make some changes in order to make it work.
I've first prepared ISA.
I'm using an Enteprise CA(Windows 2003 Standard R2 SP2).