Remote Access of Home Network from Mobile Device using DLNA and Linux RIKARD GUSTAFSSON AND GUSTAV REIZ Master’s Thesis at the Department of Computer Science Advisor/Examiner: Boris Magnusson Advisor: Stefan Ekenberg February 15, 2010 Abstract In today’s technically aware society comfort has become a big demand. From this demand the DLNA standard rose up in order to let people fuse all of their technical devices together, to share, to view and to transfer their digital content. In parallel with this development, our mobile phones are evolving into more and more advanced multi-purpose devices which we rely on in many of our daily activities. In this Master’s Thesis the aim is to conjoin these two trends in order to develop a prototype system in which a user is able to control his home network with the use of a mobile phone over the cellular network or when connected to the Internet through Wi-Fi. The user will be able to connect to, and control, his home network and the devices within. Analysis of available related solutions, the advantages and disad- vantages of them, are first presented. A new, more suitable, solution is thereafter proposed. Referat I dagens tekniskt medvetna samhälle så har bekvämlighet blivit ett stort krav och det är utifrån detta krav som den nya DLNA standarden växte fram. Med hjälp av DLNA möjliggör man för användare att integrera sina tekniska enheter med varandra. Därigenom förenklas möjligheterna att dela, titta på och hantera digital media. Parallellt med denna utveck- ling så blir våra mobiltelefoner mer och mer avancerade och spelar en allt större roll i vår vardag. Det här examensarbetet ämnar att koppla samman dessa två tren- der för att utveckla ett prototypsystem som skall kunna används för att kontrollera ett hemmanätverk via en mobiltelefon över det cellulära nätverket eller via Wi-Fi. Visionen är att en användare skall kunna, givet att han har Internetuppkoppling, ansluta till och kontrollera sitt hemmanätverk enbart med hjälp av sin mobiltelefon. Analys av redan existerande lösningar, dess för- och nackdelar, som berör ämnet med “Remote Access” kommer att presenteras. Utifrån vad som finns tillgängligt idag så kommer en lösning, för att uppnå full kontroll över sitt hemmanätverk, att beskrivas. Acknowledgement We would like to express our gratitude to everyone who gave us the possibility to complete this Master’s Thesis. We would especially like to thank our advisor Stefan Ekenberg at ST-Ericsson for his valuable comments and guidance throughout the course of the thesis and Johan Sörensen at ST-Ericsson for his comments and suggestions. We would also like to thank our examiner Boris Magnusson on LTH for his time spent on reading and commenting the thesis. Finally we thank Mikael Torstensson at NetOnNet for allowing us to use images from their website as part of our illustrations. Contents 1 Introduction 1 1.1 Background . 1 1.2 The Work Process . 2 1.3 Terminology . 4 2 DLNA Overview 5 2.1 Introduction . 5 2.2 Evolution of DLNA . 6 2.3 Device Model . 7 2.4 Device Classes and Categories . 7 2.4.1 Home Network Device Category, HND . 8 2.4.2 Mobile Handheld Device Category, MHD . 9 2.4.3 Home Infrastructure Device Category, HID . 10 2.5 Device Interaction . 10 2.5.1 Interaction Examples . 11 2.6 A Typical Home Network . 12 3 Analysis 15 3.1 Related Work . 15 3.1.1 DLNA Proxy System . 15 3.1.2 W-DLNA . 16 3.1.3 xUPnP . 17 3.1.4 Web Based User Interface . 18 3.1.5 Atom Architecture . 18 3.2 Related Techniques . 20 3.2.1 DD-WRT and OpenVPN . 20 3.3 Developement Libraries for UPnP . 21 3.3.1 Intel’s libupnp . 21 3.3.2 Cyberlink for C++ . 21 3.3.3 GUPnP . 21 3.3.4 Platinum . 22 3.3.5 Allegro RomPlug . 22 3.4 Possible Solutions . 22 3.4.1 Client & Server Application . 23 3.4.2 Ethernet Bridging using DD-WRT and OpenVPN . 25 3.5 Choosing an Approach . 27 4 Design and Implementation 29 4.1 Tools and Hardware . 29 4.2 VPN Bridge Setup . 29 4.3 Remote DMC . 31 5 Limitations 35 5.1 Router Bottleneck . 35 5.2 Power Consumption . 36 5.3 Multi-Interface Support . 38 6 Conclusions 39 7 Future Work 41 Appendix 41 A User manual - OpenVPN 43 A.1 Getting Started . 43 A.2 Generating Certificates and Keys . 43 A.3 Configure the Server . 45 A.4 Configure the Client . 48 B User manual - RG DMC 51 B.1 Getting Started . 51 B.1.1 Installation on a Debian Based System (e.g. Ubuntu) . 51 B.1.2 Installation on a Linux System. 52 B.2 Installation . 52 B.3 Starting the Application . 53 B.4 Using the Application . 53 B.4.1 Console View . 53 B.4.2 GUI View . 56 Bibliography 59 Chapter 1 Introduction This opening chapter will give an introduction to this Master’s Thesis, its purpose and background in Section 1.1, and the work process behind it in Section 1.2. In Chapter 2 an introduction to the DLNA standard will be given. Chapter 3 will present already developed solutions, techniques and tools relating to the problem with remote access to home networks. Chapter 4 will describe how the solution was implemented. Chapter 5 will show some limitations with this solution. Chapter 6 will summarize the Master’s Thesis and the solution developed. Chapter 7 will suggest future work which can be conducted in the area of DLNA and remote access. 1.1 Background People today are becoming more and more dependent on digital media and con- necting different media entertainment systems. They are acquiring, viewing, and managing media to a larger and larger extent. Having many different media de- vices at home which can not directly communicate with each other forces users to utilize extra devices or transport agents such as DVD-discs. Taking the common case where a person wants to play his home videos, stored on his computer, on his TV. The first thing he will have to do is to convert the video to a format that is supported. Then it needs to be burnt to a DVD disc and played in the DVD player. This has resulted in a greater demand for comfort and that is where the Digital Liv- ing Network Alliance (DLNA) standard becomes important. The goal with DLNA is to allow technical devices to interact with one another in order to create a flexible home network where digital media can be viewed, shared, and managed in an easy way without the need for any additional software or advanced configuration of the devices. DLNA is based on the Universal Plug and Play (UPnP) protocol standard which specifies a set of guidelines on how technical devices can discover and interact with one another in a Local Area Network (LAN). This introduces a limitation due to the UPnP discovery mechanism, which limits its use to a private IP configured home 1 1.2. THE WORK PROCESS network since it uses multicast packages [2]. Multicast packages are often limited to a LAN since Internet routers often blocks multicasts in order to reduce network traffic. What if a user wants to access and control his home network from a remote location outside the LAN? Picture a scenario where a user is stuck in traffic and his favorite show is about to start, or maybe his kids are home alone and he need to keep them entertained. What does he do? Wouldn’t it be fantastic if he, just by connecting to the Internet, would be able to manage his Digital Video Recorder (DVR), and access his previous recordings? By gaining this control he would be able to record the show he does not want to miss, or play a previously recorded cartoon show on his TV for the kids. This is the type of scenarios that this Master’s Thesis aims to enable. With a DLNA network setup at home one will be able to connect to it remotely using a mobile phone (given that Internet access is provided) and control all the devices, and the services that they provide, within that network. 1.2 The Work Process During the course of this project we were located in the office building of ST-Ericsson in order to work closely with our advisor at the company. We were given our own workstations, with one computer each. We treated the project as a somewhat real employment, working 8-15 four days of the week and 8-12 on Fridays, and extra when needed. We started off the project by making a work plan to get a clear overview of the project and what tasks it involved. The plan could be divided into the three parts Analysis, Implementation, and Documentation. During the Analysis part we studied the DLNA standard, which were completely new to us at the time. We also analyzed other solutions aiming to solve the problem with remote access to home networks. After familiarizing ourselves with the problem at hand, and with a greater insight in the DLNA standard, we created our own solution. With an idea for a solution we proceeded to implement and design it, during which we formulated the solution on paper and finally in code. During the devel- opment of our solution we had a few demonstrations of our work for our advisors to keep them updated on our progress and to gain feedback. When developing our solution we had a network set up at Gustav’s apartment which we connected to in order to test our implementations.