The OpenVPN server configuration:
# cat /etc/openvpn/server.conf
port 1194
proto udp
dev tun
ca /etc/openvpn/open-rsa/keys/ca.crt
cert /etc/openvpn/open-rsa/keys/server.crt
key /etc/openvpn/open-rsa/keys/server.key
dh /etc/openvpn/open-rsa/keys/dh1024.pem
server 10.8.0.0 255.255.255.0
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 60
comp-lzo
persist-key
persist-tun
status 1194.log
verb 3
client-config-dir ccd
The client-specific configuration, which specifies which subnets are accessible on the client:
# cat /etc/openvpn/ccd/android
iroute 10.42.242.0 255.255.255.0
Enable IP forwarding
# grep ip_forward /etc/sysctl.conf
net.ipv4.ip_forward=1
# sysctl -p
Enable NAT
# iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
# service iptables save
Export the client certificate and private key using PKCS12 in order to then import them into the OpenVPN Client for Android:
# openssl pkcs12 -export -in /etc/openvpn/open-rsa/keys/android.crt -inkey /etc/openvpn/open-rsa/keys/android.key -certfile /etc/openvpn/open-rsa/keys/ca.crt -name android -out /tmp/android.p12
The resulting android.p12 file can be sent to the Android device, and from there have it imported into the OpenVPN Client for Android.
felipe-alfaro.com 
Can the VPN server run on another android device? Like from a tablet with a secure internet connection?
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