I have VPN access to my home network from my Samsung Prevail over both wifi & 3G.
The steps bellow assume you already have a working OpenVPN server on your network & you are able to connect remotely from another computer using the OpenVPN client. I also assume your Prevail is already rooted, already has buysbox installed (comes with the few roms available for our phone), & you are somewhat familiar with using either a terminal emulator on your phone, through Droid Explorer, etc.
First you must download the tun.ko file for the Prevail. The one I compiled can be found at:
https://rapidshare.com/files/4022896828/tun.ko Save the file to your sdcard then turn off USB storage so the file is available from the terminal session.
In the terminal, type
Code:
su
mount -o remount,rw /rootfs/ /system/
cp -f /sdcard/tun.ko /system/lib/modules/
chmod 644 /system/lib/modules/tun.ko
Now exit the terminal session. Download & install OpenVPN Installer from the market place. After the installer finishes, download & install OpenVPN Settings from the market place.
Copy your OpenVPN certificate files to a folder called "OpenVPN" on your sdcard. ie: /sdcard/openvpn/ca.cert
On your prevail, launch OpenVPN Settings. Tap your menu button on the Prevail then select Advanced. Tap on TUN module settings. Change Load module using to insmod. Enter "/system/lib/modules/tun.ko" in the Path to Tun box. Go back one menu. Make sure your path to configurations & binary are correct. If everything looks good, click the check box next to Load tun kernel module. Now go back to the main OpenVPN Settings screen and check both boxes. If everything is configured correctly, you should connect to your VPN within a couple of minutes.