There is VDS hosting. Debian. There is a desire to lift on it VPN to protect against snipe in open WiFi networks.
The scenario I see something like this: connect to public wifi (clients: Android2.2, iOS4, Windows 7), connected to VPN, all traffic is encrypted and goes through it.
Accordingly, there is the task of selecting and VPN settings that would power up the clients (Win, iOS, Android), it was possible for him to use.
* On Android, the following configurations are available: pptp, l2tp, l2tp/IPSec PSK, l2tp/IPSec CRT.
* On iOS L2TP, PPTP Cisco IPSec VPN.
* On Windows the standard client (something you can deliver, probably).
* Simultaneous clients can be up to 4x.
* Circuit settings VPN: routera, access via login/password.
Alternatively you can consider a PPTP server configured with forwarding: