Launching and Connecting

Transcription

1 Module 7 Launching and Connecting Introduction In this module we are going to learn how to launch an instance and how to connect to it. We are going to discuss two ways to connect: (a) with the command line and (b) to a remote desktop, with the benefits of having a graphical interface. We will briefly take a look at how to run graphical applications via the command line (instead of the remote desktop), and we will also set up a web server to publish a very simple website. Finally, we will set up the different cloud storage types, so we can access the storage remotely and directly from our instance. Videos The following videos go through most of the content in this module and offer a less indepth description of the subject than the documentation does QNQsZ4 General notes What is an instance? In Module 5 we have already discussed in more detail what an instance is, but let s do a little recap at this point. In the NeCTAR Research Cloud, an instance is a virtual machine. Instances running inside the Research Cloud are just like real life computers, except that they run remotely, in the Cloud. Here and when learning about them on the web, you will often find them referred to as instances.

2 Instance vs local computer In this document we will often talk about the local computer as opposed to the instance. The local computer is the one you are probably sitting in front of right now: It is your home or office computer that you use to connect to the instance. The instance is your virtual machine that is running in the NeCTAR cloud. You may be familiar with connecting to remote computers already. You may have connected to a remote desktop, or used a command line. The same tools and techniques apply when connecting to running instances. Your instance has a public IP address and can be reached and controlled with any remote access tools you wish to use, after you have set it up for remote access. For example, you can use an SSH terminal, or alternatively connect to your remote desktop. In this module we will create and launch an instance (a virtual machine, short: VM) and go through the two options on how you can connect to your instance (terminal and remote desktop). Use of Terminals Throughout the exercises, we will use a Terminal to type commands. To prepare, make sure you know how to open your Terminal by following instructions below for your Operating System. On Windows, you will use two terminals: The PuTTY terminal to connect to and type commands for the instance. You will need to download PuTTY: You will need the files PuTTYgen.exe and the file Putty.exe from the official PuTTY website. This Terminal will be referred to as the ssh terminal. The Windows command line on your computer. You can open it by typing cmd into the search field (on Windows < 8 on Start ; on Windows 8 in the App search field). This Terminal will be referred to as your local Terminal. On Mac and Linux, there are built in terminals available. You can access them as follows: On Linux Systems, depending on your desktop environment, opening a terminal is usually achieved by clicking on the terminal symbol, or by right click on the desktop and select Open Terminal. On a Mac, you can open a terminal as follows: 1. Bring up Spotlight Search by holding down the Command and Spacebar

3 keys simultaneously. 2. In the search box that appears, type Terminal and press the Return key. Alternatively, in the Finder, go to Applications > Utilities and you will find the Terminal app there. Conventions The notation throughout the training documents can be interpreted as follows: Words in italics are used for names and terminology, e.g. name of a software, or name of a computing concept. It may also just emphasise a word in the traditional way. Quotations are also written in italics and are put in between quotatioin marks. Words in bold are used to highlight words which identify important concepts of a paragraph, to make it easier for users to skim through the text to find a paragraph which explains a certain idea, concept or technology. Additional information which is optional to read is displayed in info boxes like this one. Important information is displayed in boxes like this one. Definition of terms are displayed in boxes of this style. Possibly specific prerequisites for reading a particular section are contained in this type of box at the beginning of a section. The use of command line tools is part of this course. In a Terminal, you will be directed to type in commands. Commands are formatted as follows: command-name argument1 argument2... argumentn Throughout the exercises, when you see a word in pointed brackets, like <this word>, it means that you have to replace everything inside the brackets, and including the brackets, with whatever is described within the brackets.

4 For example, if you are prompted to run a command named the command which takes two arguments: the-command -f <yourfile> Then you have to replace the second argument, <yourfile>, with the file name that is being referenced in the exercise. For example the-command -f thefile.txt When editing a file, the contents of it will be displayed in a different font and with background colour as follows: The content of the file The next line in this file Output on the command line terminal is printed in boxes formatted as follows: NectarInstance:~ Jennifer$ whoami Jennifer Create a ssh key First, we will need to create a ssh key pair for connecting to our instances. An ssh key pair is required to encrypt the data which is transferred to communicate with the instance. The pair consists of two keys: A private key, and a public key. The public key is called public because that s the one which is placed on the server and which you may upload online without worrying about security issues. It is useless without its counterpart, the private key. The private key is the secret key which you keep on your local computer so that you may connect to the instance. You should keep the private key very safe and never share it with anyone. Take care not to lose it, otherwise you won t be able to connect to your machine. The connection to the machine only works with both keys.

5 The image above shows two computers connected through their ports, with an ssh server and client encrypting the connection. Applications can use this secure ssh connection to exchange data. We will first have to generate this key pair before we can proceed with launching an instance. The ssh keys will have a name. You should choose a name that you can associate with your instance, for example Nectar_Key. As a general rule of thumb, file names should consist of alphanumeric characters and underscores ( _ ) only. You should avoid white spaces. They makes working with files on Unix systems a bit clumsy. Note: The process differs between Unix/Mac Systems and Windows. Follow the steps described below for your platform, and then continue to the next section. Mac and Linux SSH key pairs can be generated with the ssh keygen command. If you choose Nectar_Key as your key name, you will have two files after the generation of keys: The private key, called Nectar_Key and the public key, called Nectar_Key.pub. 1. Open your Unix or Mac Terminal. You will start off in your home directory. If you already had the terminal open before, make sure you are in the home directory, by simply typing cd Now, check if you already have a directory called.ssh, by typing ls -a A list of files in your home directory will be printed. If you don t see the name.ssh in this list, create the directory (if you see the directory, skip this command): mkdir.ssh and change to this directory: cd.ssh Now generate the key with ssh-keygen -t rsa -f Nectar_Key This generates a pair of keys in the directory.ssh, which is the default location for ssh keys. You will be asked to specify a passphrase. Choose a secure passphrase! But make sure that you store your password somewhere safe you will not be able to connect to your instance if you forget the password! 2. You will have generated (1) a key you keep private, named Nectar_Key and (2) a

6 public key, named Nectar_Key.pub. If you type ls Then you should see both files listed. 3. Open the public key file with your favourite text editor. If you don t have a favourite editor, here are some suggestions: On a Mac, type open -e Nectar_Key.pub which should open the key in TextEdit. On a Linux gnome environment (e.g. Unity), type gedit Nectar_Key or if you are using KDE, type kate Nectar_Key If you are using another desktop environment we assume you are familiar with your favourite text editor. 4. Copy all the text which is contained in the file Nectar_Key.pub into the clipboard. With CTRL+A you can mark all text, and with CTRL+C copy it (on a Mac it is Command ( ) instead of CTRL). You will need the contents of the public key on the keyboard in one of the next steps. Windows Open the PuTTYgen program by clicking on PuTTYgen.exe which you downloaded in the beginning of this tutorial. 1. For Type of key to generate, select SSH 2 RSA. 2. Click on Generate. 3. Move your mouse in the area below the progress bar. When the progress bar is full, PuTTYgen generates your key pair. 1. Type a passphrase in the Key passphrase field. Choose a secure passphrase! Type the same passphrase in the Confirm passphrase field.

7 2. Right click in the text field Public key for pasting into OpenSSH authorized_keys file and choose Select All. Right click again in the same text field and choose Copy. This copies the content onto the clipboard, we will need to paste it somewhere else in one of the next steps. 3. Click the Save private key button to save the private key. It is important that you save the key, because you will need the file later. So save it in a folder where you can find it again. In this exercise, we will name the file Nectar_Key.ppk. 4. Save your public key as well by clicking the Save public key button. As a file name, type Nectar_Key.pub.txt. Launching an instance We will now create an instance and choose the resources we require. For this tutorial, we don t need a lot of resources. You may require more for your research. For more details about how to request an allocation, see Module 5. Security note Before we start, a brief note about security: It is important that we make our instance secure from the very moment we create it. In order to enable the right security settings, we will select the instance to be part of one or several security groups. A Security Group opens up access to the instance from outside. Essentially, a security group is a collection of firewall rules, which open up different Ports to access the machine from outside. Module 5 has already introduced the concept of Ports. Now we need to free up some Ports in order to be able to communicate with our instance. For example, we will first connect to our instance with a SSH shell from our terminal (Reminder: SSH encrypts our communication with the server). SSH uses Port number 22, so this has to be freed up.

8 Note: All the pre defined security groups mentioned in the instructions are available in Project Trials only. To learn how to create your own security group (or re create the trial groups), refer to the Appendix of this module. The following steps will explain how to create an instance and how to make sure it has been assigned to the security groups we need to connect to it. Step 1: Logging on First, we will have to log on to the Dashboard, which is our interface for managing our virtual machines. The Dashboard can be accessed with any browser, e.g. Firefox, Safari or Windows Internet Explorer. Open your browser of choice (we suggest Firefox), and go to: Click Log in on the first window. Then, select your organisation from the dropdown menu (you may also type in the first characters of your organisation name in order to find it quicker). You will be redirected to a page where you can type in your username and password. This should in most cases be the username and password you usually use to access your account at your University or Research Organisation. Click OK for all terms and conditions if logging in the first time (you will not have to do this every time). Step 2: Open the Launch Dialogue Go to Dashboard > Instances. A list of your running instances will be listed. If this is the first time you are doing this, the list will be empty. Now click on Launch instance on the top right of the overview.

9 Step 3: Selecting resources Choose the name of your instance and the flavor. Different flavors allocate different amounts of memory and disk space for you. Select the flavors in the dropdown box and information about the resources are displayed on the right side of the window. You may select a few flavors to see the differences between the flavors. For this tutorial, choose the flavor m1.small, which offers 30GB of ephemeral storage (we will need this in a later section. You could launch several instances of the same flavor, but for now we will launch only 1, so leave Instance Count at 1. Leave Instance Boot Source on Boot from Image. Choose the most recent version of NeCTAR Ubuntu from the Image name list. NOTE: At the time of writing the image NeCTAR Ubuntu (Utopic) amd64 was used. If you choose a version much newer than this, there may be some differences to the descriptions given in this tutorial. In general, a newer version should work fine with the exercises below, you may only see different text (phrasing) in the terminals command line output. Don t click Launch just yet we have to set the security settings first!

10 Step 4: Ensuring security Now, we will choose the security settings. Go to the tab Access & Security. We can choose which Security Groups the instance will belong to (see above for explanation about security groups). We will connect to the instance with ssh. Ssh uses port number 22, so this has to be freed up. Therefore, tick the ssh box. We will also publish a little website in a later exercise, which requires http, so tick the http box also. To test whether your instance is reachable, we will also need icmp. Note: We can also change the security groups of the instance later on, but it s convenient to do this now. Next, we will specify the key for connecting to this instance (that s the one we just generated). 1. You should have the contents of your public key still in your clipboard, unless you have copied and pasted something else since we did this above. If you have, copy the contents of Nectar_Key.pub again. 2. Click on the plus ( + ) to add a new key. 3. Specify the Key Pair Name. This can be any name, but for simplicity choose Nectar_Key also. 4. Paste the contents into the large text box labelled Public Key (use CTRL+V, or right click in the box and Paste ). 5. Now, click Import key pair. This key will now be available for future use. Next time you launch an instance you can select this key from the drop down list directly, without having to copy and paste it again. The window closes and you are back to the window to configure your instance. Step 5 (optional): Choose your Availability zone

11 If you need access to specific facilities (e.g. Volume storage), you can manually choose the location of your instance in the Availability Zone tab. The Availability Zone is where your instance will be running physically. Unless you know that you need access to specific services, it is recommended to leave this in the default setting, because then the location with the most available resources is chosen. Step 5: Launching the instance You can now launch the instance by clicking on the Launch button. You will get back to the overview of your instances. You will see the status of your instance in the overview. You need to wait a few minutes. The Instance will normally pass from Status Build to Active. You will see an IP address for your instance (4 numbers separated by a dot). Write it down, or keep this window open so you can see it, as we will need it in the next step to connect to your instance. Congratulations!! Your instance is now reachable on this IP address. Your applications can connect to the Ports that you have allowed earlier in the Security Groups. Connect to the instance To connect to your instance, you will need its IP address. You should have just written this down, or you can look it up on the Dashboard (Compute > Instances). In the following text, your IP address is described as NNN.NNN.NNN.NNN, which you will have to replace with your own instance s IP address. To get a secure connection, we need to log on to the instance via ssh. Connect via ssh Step 1: Test connectivity First, let s do a little test to see if your instance is reachable. On Linux/Mac, you can use the command line shell that you have just opened. On Windows, open your Windows command line.

12 Use the terminal to try to ping your instance (checking that you can reach it): ping NNN.NNN.NNN.NNN replacing the N s with the IP address of your NeCTAR instance you noted above. The ping command just sends a simple signal to your instance and checks whether it responds. If the ping does not work, then most likely neither will any of the following steps. The ping has worked if you get a response every few seconds, e.g. PING ( ) 56(84) bytes of data. 64 bytes from : icmp_seq=1 ttl=49 time=354 ms 64 bytes from : icmp_seq=2 ttl=49 time=358 ms Step 2: Logging in We will now log in to our instance using ssh with the private key (the username might be different depending on the image you launched). Follow the instructions below for the operating system of your local computer. Note: If the ping has worked but the SSH connection does not work after following instructions below, follow the troubleshooting steps in the Appendix. Linux/Mac We will need a command line shell (a Terminal ) in this exercise. On Linux and Mac, you have a built in terminal. Open it now (if you are unsure how, refer to the notes in the introduction). Go to your command line and type ssh -i Nectar_Key ubuntu@nnn.nnn.nnn.nnn using your own IP address instead of NNN.NNN.NNN.NNN. The command line will ask you to establish the authenticity of the server. Type yes. You will then be asked for your passphrase (that s the one you chose when generating the SSH Key). Note: If you named your key other than Nectar_Key, you should replace this with your own private key file name here. If you saved the private key in another folder, you will have to specify the full path to it (e.g. ssh i /home/john/yourkeyfolder/nectar_key NNN.NNN.NNN.NNN). On a Mac:

13 You may have to specify the full path to the key. If the above does not work, try instead: ssh -i $HOME/.ssh/Nectar_Key Our instance has a default username that we need to specify when we log in. In this tutorial, we chose a Ubuntu Image when launching the instance. At the time of writing, the user name for Ubuntu is ubuntu. Other NeCTAR images may expect different usernames. Try using root instead of ubuntu ( root@nnn.nnn.nnn.nnn ) for other Operating Systems. For Fedora, the user name may be ec2 user. The right user name for the image you chose is documented at the NeCTAR Image_Catalog. Well done! Now, you should be connected to your instance and your ssh terminal command line is ready to use. Windows On a windows system, we will use the PuTTY terminal to connect to the instance. We first have to set up our PuTTY session to include the details of our instance, including the keys we are using. Double click on the file PuTTY.exe which you downloaded when you created the SSH key. In your PuTTY Window, type your instance s IP address into the Host field (you should have taken a note about the IP address earlier, if not you can find it on the Dashboard: Go to Compute > Instances).

14 Then, select the Data category in the navigation window. Here, we will have to specify the username. Choose ubuntu as your username. Leave the other fields on default settings. Our instance has a default username that we need to specify when we log in. In this tutorial, we chose a Ubuntu Image when launching the instance. At the time of writing, the user name for Ubuntu is ubuntu. Other NeCTAR images may expect different usernames. Try using root instead of ubuntu for other Operating Systems. For Fedora, the user name may be ec2 user. The right user name for the image you chose is documented at the NeCTAR Image_Catalog. Next, click on the SSH > Auth sub category. There is a field labelled Private key file for authentication. Click on the Browse button:

15 In the browse window that comes up, select the private SSH key file that you saved on your computer earlier (we named it Nectar_Key) Note: If you have generated your ssh key on a Linux system and now need to convert it to Windows, see how to do this in the Appendix. Instead of converting keys, you can also simply create a separate set of keys to use with PuTTY. In this case, you have to add the new key as an authorized key on the instance. See the Appendix for instructions on how to do this. Now, return to the Session screen in the left navigation window. This is the screen we started at. We will save our settings (the session ), so that in future we don t need to type in all the details again. In the Saved Sessions section, choose any name for this session so that you can remember it, for example MyNeCTARInstance. Then, click on the Save button.

16 Now, connect to the instance by clicking the Open button. The first time that you connect, you will be asked to verify the identity of the remote server. This is expected the first time you connect to a new server, so you can select Yes to continue. You will be prompted for a passphrase. Type in the passphrase that you used to create the SSH key earlier on. Every time you connect to the instance via Putty, you will have to type in your passphrase. This may get a little cumbersome, so note that there is a tool called Pageant that you can get on the same page where you downloaded PuTTY. Pageant is an SSH authentication agent. It holds your private keys in memory, already decoded, so that you can use them often without needing to type the passphrase every time. It also eliminates the need to explicitly specify the relevant key to each user account, if you use more than one account to log into a server. We will not use pageant in this tutorial, but you may be interested to read up on how to use it. You can find instruction in the Appendix. Well done! Now, a black Terminal window should open and your command line is ready to use. Configuration and control Welcome to your new virtual machine! First of all, we want to make sure our system is updated. On Debian and its derivatives, like Ubuntu, you can update your packages with the commands: sudo apt-get update sudo apt-get upgrade The first command refreshes the package information, and the second upgrades your system. There are several ways to upgrade your system. The command above (sudo apt get upgrade) simply updates the existing packages. You can also update more intelligently. Here s a description of the various upgrade commands (extracts from the apt get manual): apt get upgrade: upgrade is used to install the newest versions of all

17 packages currently installed on the system [..]. Packages currently installed with new versions available are retrieved and upgraded; under no circumstances are currently installed packages removed, or packages not already installed retrieved and installed. New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version. apt get dist upgrade: dist upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt get has a smart conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. So, dist upgrade command may remove some packages. apt get full upgrade: full upgrade performs the function of upgrade but may also remove installed packages if that is required in order to resolve a package conflict. You may also want to change the password for the user ubuntu: passwd Note: You will not be prompted for your ubuntu user password when you connect through ssh. This is because in the default configuration, the ssh key is regarded sufficient for authentication purposes. Therefore, each user on the virtual machine should have their own ssh key. More importantly, you should change the password for root access (administrator rights), especially if you are planning to add more users to the virtual machine: sudo passwd root and type in the new password twice. If you do not change the root password, and later add other users to the VM, any user will be able to log in as root and perform administrator tasks (using the command su ). When you create new user accounts, and you do not want them to have root access, make sure you do not include them in the user group sudo. Any user which is member of this group can execute administration tasks.

18 Having problems connecting? The Appendix includes a section on troubleshooting. Using a command line text file editor Sometimes, we will have to edit files on the instance via the command line. Because this is a command line, we cannot use programs like Word or inote to edit a file. Instead, we have to use a command line editor. There is a large number of command line editors available. A simple and easy to use editor is nano. Vim is also popular but a bit more difficult to use for beginners. If you want to edit a file, type nano <path-to-your-filename> The terminal changes into a simple editor. You can edit the file and then exit the editor with Ctrl+X. A prompt will come up asking if you want to save the file, type Y to confirm this. We will create a file to test this. Type nano MyFile.txt and hit enter to confirm the command. Write a little story or anything you are just thinking of into the file. Then, hit Ctrl+X to exit, and confirm with Y that you want to save the file. Now, type ls and hit enter to confirm the command. You will see the list of files that are there. The list should contain a file MyFile.txt. You may print the contents of the text file onto the terminal by typing: cat MyFile.txt and you should be able to read your message in the terminal. Exit again with Ctrl+X. Restarting your instance Sometimes, you may want to restart your instance. For example, to make sure everything works correctly after you installed some packages. You can do this in the Dashboard. Step 1. Reboot on the Dashboard. Go to the Dashboard and click on Instances on the navigation panel on the left to see

19 your instance. On the right side of your instance, you can open up a drop down box. click on Soft Reboot Instance (a soft reboot is what we know as a reboot. A hard reboot forces the reboot in case the soft reboot does not react). Step 2. Re connect ssh client. Your ssh session, or the PuTTY session if you are on Windows, will have disconnected now, so you have to re connect. On Windows PuTTY, you should have your login session still saved so you just need to load these settings up. On Mac and Linux, simply re run the ssh command (Tip: you can browse the command line history with the up/down arrow keys in your ssh terminal. Your ssh command should be in there so you don t have to type it again). Tip for Unix/Mac You can make your life a bit easier by saving your configuration for the ssh connection. This will avoid always having to type your IP address. There is two options to do this: a) specifying all details or b) creating an alias for your IP address. Then, instead of typing in the full ssh command every time, you will just do the following: Option 1: ssh MyNectarInstance Option 2: ssh -i Nectar_Key ubuntu@mynectarinstance Option 1 You need to edit a file on your local computer (not on the instance!). Open a new terminal on your computer. Then, open up the file ~/.ssh/config using your favourite editor, for example:

20 nano ~/.ssh/config and add the following contents: Host MyNectarInstance HostName NNN.NNN.NNN.NNN User ubuntu IdentityFile ~/.ssh/nectar_key Again, replacing the N s with your IP address. You can choose any other alias name instead of MyNectarInstance. Save the file and close it. From now on, you can connect with the command: ssh MyNectarInstance or, if you chose another name, replace MyNectarInstance with it. Option 2 You may also just alias your IP address in the system s host file. On Unix systems and on Mac 10.2 and newer, the file to edit is usually the file /etc/hosts. On Mac 9 and earlier you can find it in the Preferences or Systems folder. Open this file in your favourite editor, for example: sudo nano /etc/hosts and add the following line: NNN.NNN.NNN.NNN MyNectarInstance replacing the N s by the IP address of your instance. You may also choose another name instead of MyNectarInstance. Next time you ssh into the instance, you can connect with: ssh -i <path-to-your-keyfile> ubuntu@mynectarinstance Note this is the same command we used earlier, but you can type MyNectarInstance instead of your IP address. You will be asked to accept the authenticity of the host again. Answer with yes. Connect to a remote desktop Using the command line may not feel very intuitive, especially for beginners. Aside

21 from that, sometimes we need to run software that has a graphical interface. As an alternative to connecting with a ssh terminal, we can also connect to the desktop of our instance and get a graphical interface as we know it from our own computers. A remote desktop login allows users to connect to their desktop while being physically away from their computer. You can also connect to your own home computer s desktop while you are away, if you set up your home computer accordingly with remote access. This may be a bit difficult to do from your organisation or from your home, as you need access to the computer via the internet from outside, which may require the permission of firewalls used on the premises, and you need a fixed IP address. However on your NeCTAR instance, it is easy to set up a remote desktop, because the instance is already accessible from outside. Some remote desktop solutions allow only one user to see the desktop at the same time. Other software also allows desktop sharing in which several users can see a desktop simultaneously. Such a shared desktop can be used as a platform for real time collaboration. This mostly requires a separate setup, which is not part of this tutorial. To connect to a remote desktop, the remote machine (your instance) has to have a remote desktop server installed and running. On your home or office computer, you have to install a remote desktop client (sometimes called viewer ) which connects to the remote desktop server on your instance. The client then displays the desktop of your remote machine. It is like a window into your instances desktop; The desktop environment itself is running on the instance. Terminals on remote desktop vs SSH terminal We have previously connected to the instance with via a ssh terminal. When we get a window into the desktop of our instance, we can open a terminal on the desktop as well. The image below shows both (1) a ssh terminal (left) and (2) a desktop with an open terminal (right):

22 So what is the difference between the two terminals? When you type commands in either of them, it will have the same effect. They are both terminals that you can use to control your instance. However, the difference is that 1. The ssh terminal is set up through a secure ssh communication line with your instance. If we use a ssh terminal, only text is being transferred (the commands you type and the responses you get). This is very fast, but you cannot run graphical applications, because you can only communicate with the instance via text. Note: it actually is possible to run graphical applications via the terminal as well, with some disadvantages. This is discussed later in this module, but this is very slow and usually not recommended. 2. The terminal on the remote desktop is connected securely as well (at least the way we will set it up in this tutorial). But instead, the communication includes graphical data and events (e.g. your mouse clicks, and the windows displayed). This is slower than using the terminal only, but you may find it is still fast enough to work with. You can run graphical applications and use the OS menu to find programs and change settings, which may be easier for many of us. Remote desktop protocols When you are connected to a remote desktop, everything you do to interact with the system, for example clicking the mouse, moving a window or typing on your keyboard, is communicated to the remote machine (in this case, your instance). For this kind of communication, computers use protocols which are designed for this purpose. The type of protocol determines properties of the remote desktop, for example how secure it is, how fast it works and what kind of desktop environments it supports. In

23 this tutorial we will use two different protocols to connect to our remote desktop: NX and VNC. Some wide spread protocols include: RDP (Remote Desktop Protocol) Originally developed by Microsoft to connect to Windows machines. The protocol is not very secure, therefore setting up tunneling through a secure connection is required. NX NX compresses the data to minimize the amount of information transmitted. NX also caches data to make the session as responsive as possible. For example the first time a menu is opened it may take a few seconds, but on each subsequent opening the menu will appear almost instantly. Therefore, NX allows fast speed even with slow internet connections. NX uses the SSH protocol to send its data and is therefore secure. VNC (Virtual Network Computing) The VNC Protocol (called the RFB protocol) is very simple. It is based on graphic primitives from server to client ( Put a rectangle of pixel data at the specified X,Y position ) and event messages from client to server. This makes VNC a bit slow. By default, this is no secure protocol. Therefore, you need to tunnel the connection via a secure SSH connection to make it secure. This may seem a bit complicated to achieve for beginners. Alternatively, some clients like UltraVNC) support the use of an encryption plugin which encrypts the entire VNC session. Because VNC is quite popular, the client software options are pretty good for Unix and Windows platforms. VNC allows multiple users to see (share) the same desktop. To transfer files, printing or audio requires separate services. The VNC only handles displays and inputs, such as interaction with keyboard and mouse. Users may access desktops with VNC through their Web browser, without needing to install separate viewer applications. VNC displays a desktop within a browser window by running a Java applet, and this facility should work on any system that has a JVM installed. VNC does not support the newer 3D desktops (e.g. the newer GNOME/Unity or KDE desktops environments. The desktop environments have to be run in classical 2D mode for it to work (e.g. GNOME Flashback).

24 To learn more about VNC, here is a good article Free remote desktop client and server software includes: Vnc4server the main VNC server software for Linux. UltraVNC, RealVNC, TightVNC popular clients for VNC sessions X2Go An open source product which is pretty fast. It uses the NX protocol and is operates through a secure SSH connection Supports remote audio, printing, clipboard, file sharing etc. Can share a user s session remotely, but it has to be set up separately. It is fairly easy to set up There is even a readily available browser plugin to make remotely controlling another PC possible from a web browser. But: Port forwarding and Dynamic DNS are recommended if you re using this over the Web. Due to the use of older NX libraries, it has problems with the newer 3D Desktops, e.g. Gnome/Unity and newer KDE desktop environments. Only the older environments are supported. No Android / ios client available, unless using the web interface NX Server, free edition Easy to set up Not very fast Only free to 3 users Can t share a user s session remotely. FreeNX Server A Server for the NX protocol, similar to NX Server, but free. No real good documentation, not easy to install Can t share a user s session remotely. NoMachine) A client to connect to an NX server (e.g. FreeNX). Not free for commercial use (only private) Simultaneous connections from only 2 users. NeatX (outdated) Google has released NeatX, a complete independent implementation of the NX protocol. Neatx was developed as part of an internal project which has now finished. It had no releases and is not being actively developed.

25 Can t share a user s session remotely. xrdp uses the RDP protocol (which is not very secure) Servers are also available for Unix and Mac. Commercial products may be better and easier to set up than the free software listed above, but they come at a cost (at least for commercial use). Popular software includes: TeamViewer supports Windows, OS X, Linux, Android, and ios free for personal use setup very easy pretty expensive for commercial / business use Splashtop supports Windows, OS X, Linux, Android, and ios allows you to stream audio and video across computers with minimal latency very easy to use and set up RealVNC The Official VNC software Offers its client and server apps for Windows, OS X, Linux, Android, ios, Chrome free for basic individual private use, but added features and support come at an extra cost. Wikipedia offers a good comparison of remote desktop software. The options which are easiest to set up and provide a fairly good user experience are X2GO (using the NX protocol) and VNC. In the following exercises, we will see how we can set up both of these options using freely available software. VNC vs X2Go X2Go uses the NX protocol, and VNC the RFB protocol. This makes for different properties and advantages of each approach. The VNC protocol is pixel based. This can make it a bit slow. One advantage is that it is widely used, and several available remote desktop products use this network protocol. This means that you may use any VNC viewer (client) to connect to a system that offers remote access with the VNC protocol.

26 The NX protocol (used by X2Go) has a better understanding of the underlying graphic layout than VNC (which is pixel based). Therefore, it is often more efficient (faster). In summary: VNC: inherent support of different platforms: you can install it on Unix and Windows servers is widely used, hence there is a large number of tools is slow is inherently insecure, it takes a bit more work to set up a secure connection NX (X2Go): is fast easily integrates with security plugins there are not many well maintained servers and clients available (X2Go is one of the few) Servers can only be installed on Unix servers, for Windows/Mac there are only clients (no servers) On Mac computers, installation of the X2Go client is a bit more work than on Windows and Linux, and usage can also be a little slower. Install a desktop environment First of all, for either of the options (VNC or X2Go), we need to install a desktop environment on our instance (Remember: The desktop actually runs on the instance, you only get an interactive window to it on your local computer. So we need to install a desktop on your instance). A desktop environment is what we use to graphically interact with a system (it provides the desktop, windows that open up and symbols you can click on to start a program). Windows and Mac OS have only one desktop environment, but in most Unix based systems you can choose from several environments. Popular choices are Unity, Gnome and KDE. There are also popular simple and light weight environments called LXDE, XFCE, Mate and more. You may install several desktop environments, but you only need to choose one to start with. The following desktop environments are being discussed in this section:

27 LXDE XFCE Gnome KDE If you are unsure which desktop environment to choose, we recommend you start with LXDE. Unfortunately, there is no remote desktop solution that supports all desktop environments. The desktop environments which are currently not supported for remote connections are the ones using 3D desktop acceleration. This affects e.g. Unity and Gnome3. All traditional remote desktop approaches (VNC, NX etc.) fail to work with this. Some versions of Gnome can be run in flashback Mode (with the 3D acceleration switched off), but that can be a bit tricky to set up and does not necessarily work. We will therefore discuss only the desktop environments which do work. Note: This tutorial is assuming you are using Ubuntu (UTopic), however later versions may also work with the same instructions. When in doubt, links to external documentation are given at the relevant places. LXDE This light weight environment is easy to install and works well for remote connections. Install the LXDE environment on your instance by typing into your ssh terminal: sudo apt-get install lxde

28 XFCE Install the XFCE environment by typing into your ssh terminal sudo apt-get install xfce4 GNOME Gnome will have to be run in Flashback mode to disable the 3D acceleration which is not supported in VNC or X2Go (see for example this official documentation and this one on ubuntuusers.de). X2Go is only compatible with Gnome versions earlier than 3.12 (see x2go documentation), and ideally earlier than The Ubuntu version we use in this tutorial has Gnome , so you cannot use Gnome with X2Go with the Ubuntu version used in this tutorial. However, you may still get Gnome working with VNC by following the instructions below. You can find out your Gnome version (after you installed it with following instructions) by typing in your ssh command line: gnome-shell --version If you are using a version older than 3.12, you cannot use Gnome with X2Go (you may run into trouble with versions older than 3.08 too). However, you may still get it working with VNC. To install gnome in flashback mode, follow these instructions: 1. Install the gnome environment by typing into your ssh terminal: sudo apt-get install gnome-core Alternatively, if you want to have some apps like Gimp, LibreOffice etc. preinstalled, instead of the command above, type: sudo apt-get install gnome (this will take longer as more packages are downloaded). Confirm the installation of the package with Y.

29 Hit [Enter] to confirm the message that comes up. Then, you have to select the default display manager. It does not really matter which one you choose. The correct display manager will be started by your remote client anyway. LightDM or GDM are display managers for Gnome. If unsure, just select LightDM. 2. To switch on flashback mode, we have to install a package and disable the newer scrollbars. Type: sudo apt-get install gnome-session-flashback 3. [This step is not necessary on the Ubuntu version used in this tutorial] sudo apt-get purge overlay-scrollbar gsettings set org.gnome.desktop.interface ubuntu-overlay-scrollbars false 4. [This step is not necessary on the Ubuntu version in this tutorial] You might also need the following package on older Ubuntu versions (if in doubt, install it anyway, it should already be installed and then it does nothing) sudo apt-get install xfonts-base KDE Note: Only versions earlier than KDE 5 are supported in X2Go. With the ubuntu version used in this course, you may use KDE. You can find out your version of KDE (after you installed it with following instructions) with: kde4-config -v Install the desktop environment by typing into your ssh terminal: sudo apt-get install kde-plasma-desktop Alternatively, if you want to have some more apps pre installed (this will take longer and take up more space), instead of the command above, type: sudo apt-get install kde-full Confirm the installation of the package with Y. This may take a while as a lot of packages need to be downloaded. Hit [Enter] to confirm the message about installing KDE. Then, you have to select the default display manager. It does not really matter which one you choose if there are several options. The correct display manager will be started by your remote destkop

30 client anyway. KDM is the display manager for KDE, so if unsure, just select this one. Other desktop environments There are also other desktop environments, for example MATE, which we will not discuss further in this tutorial. Connect with X2Go We will first install the X2Go Server on your instance, and afterwards the X2Go client on your local computer. Then you can access the virtual machine s desktop with the X2Go client. Server installation In this tutorial we are using Ubuntu Version on our instance and the following instructions are going to assume this. If you are using an earlier version of Ubuntu, or another Linux distribution, you may need to do other steps. This will be commented upon in the following instructions at the relevant places. See the official X2Go documentation for details on the steps to perform. 1. Add the X2Go repository and refresh the software package system by typing into your ssh terminal: sudo add-apt-repository ppa:x2go/stable and confirm this with [Enter]. Then, type: sudo apt-get update

31 2. Install the X2Go server. Type into your ssh terminal: sudo apt-get install x2goserver x2goserver-xsession Confirm the question on whether to use up the said disk space with Y 3. We now have to install extra bindings for our desktop environment which add extra features for X2Go (e.g. file sharing). Follow the instructions for the environment you want to use (if it is not listed, see official documentation) LXFE: In your ssh terminal, type sudo aptitude install lxde sudo apt-get install x2golxdebindings Note: If the installer package complains about unmet dependencies and suggests to remove lxde, say yes to this. Afterwards, re install lxde again with the command GNOME: GNOME only works for versions earlier than gnome 3.10, better earlier than gnome 3.08, as pointed out earlier). In your ssh terminal, type: apt-get install x2gognomebindings KDE: In your ssh terminal type: sudo apt-get install plasma-widget-x2go 4. The X2Go server should now be running. You can check this with typing into your ssh terminal: service --status-all grep x2go The result should show a line like this: [ + ] x2goserver If the service is running. If it isn t, you can start the server by typing: service x2goserver start If in doubt, or anything is not working, try restarting your instance before you try anything else (we have already restarted the instance here). Client installation You will now install the X2Go client on your local computer. Depending on which OS you are using, instructions will differ. Go to the instructions below for your OS. If you have a platform not listed here, you can find additional documentation on how to install the client on the official X2Go website. A good instruction can also be found here. Ubuntu: Install the client by typing into a terminal on your local computer: apt-get install x2goclient

32 Windows: Download and install the newest windows client from the X2Go website. Follow the installation wizard s steps, you may keep all default options. Max OS X: The X2Go Mac client uses the OS X X11 server called XQuartz. If you don t have Xquartz yet, you can get it on the XQuartz website. Download and install it. Note: there is also a download of the file on download.cnet.com. Search there for XQuartz. If the download speed on the original website is painfully slow, you may download XQuartz from here. Just make sure you download the newest version. At the end of the installation, it will point out that you will have to log out and log back in again for changes to take effect. You can also do this after we have changed some settings in the next step. You have to enable a few settings for Mac. Start the XQuartz server. You can find it in the spotlight search (open it with Cmd+Space), and type in xquartz to find it. Click on it to start. In the Preferences, go to the Security tab and enable allow connections from network clients. NOTE: If you start XQuartz after already having logged out and in again, you can access the settings (or exit full screen mode) with CMD +, (command and comma) Important: Because above instructions may change any time, please refer to the most current X2Go documentation Download and install the newest X2Go client from the X2Go Website. Connecting the X2Go client We will now start the X2Go client application that you installed in the last step and connect it to the instance. Step 1: Start the client On Linux, you simply type into your local computer s terminal x2goclient

33 On Windows and Mac, start the application as you do with any other program (find the x2goclient application). E.g. on Mac, bring up the spotlight (Cmd + Space) and search for x2goclient. Step 2: Start a new session The session settings should come up right away if you are using the client for the first time. If you are not, click on New session, which is the top left button that looks like a blank sheet of paper. Hint for Mac users: the X2Go windows may be sized too large for your screen initially, so you cannot see the usual OK and Cancel buttons in the dialogue windows. To resolve this, you simply have to select the window by clicking on the top window bar and holding the left mouse button to move the window a little bit. When you release the mouse button, the window should be automatically resized to fit your screen. The session preferences window should look similar to this: 1. Specify your session name in the first field (In the screenshot, we called it NeCTAR Tutorial session ). 2. In the host field, type in your IP address 3. In the Login field, specify the username (in this tutorial, it is ubuntu ).