iOS supports 3 VPN solutions: L2TP, PPTP and IPSec and currently I'm using PPTP connecting to a Ubuntu server.
Also, there are several problems: PPTP configuration has to be tunned on both ends in order to make it work and also I heard that PPTP can be broken in just 4 hours.
Is any other better solution for setting up Apple compatible VPNs that would not require buying some commercial software.