My Fritzbox 7270 was recently configured to open a VPN tunnel to my internal network. The fritzbox config is shown below in the picture:
My Desire is configured like this:
remote olkn.homelinux.net
proto udp
dev tap
tls-client
ns-cert-type server
ca /sdcard/openvpn/ca.crt
cert /sdcard/openvpn/client.crt
key /sdcard/openvpn/client.key
tls-auth /sdcard/openvpn/static.key 1
tun-mtu 1500
mssfix
nobind
pull
cipher AES-128-CBC
verb 3