Added option to download dh parameters

auto_install/install.sh

@@ -715,9 +715,14 @@ confOpenVPN() {
     # Build the server
     ${SUDOE} ./build-key-server --batch $SERVER_NAME
 
+    if (whiptail --backtitle "Setup OpenVPN" --title "Diffie-Hellman Parameters" --yesno "Generating Diffie-Hellman might take a long time on a Raspberry Pi. Do you want to download them?" $r $c)
+    then
+        # Downloading parameters
+        ${SUDOE} curl "https://2ton.com.au/dhparam/${ENCRYPT}" -o "${KEY_DIR}/dh${KEY_SIZE}.pem"
+    else
         # Generate Diffie-Hellman key exchange
         ${SUDOE} ./build-dh
-
+    fi
     # Generate static HMAC key to defend against DDoS
     ${SUDOE} openvpn --genkey --secret keys/ta.key