Setting Up VNC, SSH Tunnels, and RDP

Transcription

1 Setting Up VNC, SSH Tunnels, and RDP Thomas Pepler August 8, 2016 If you have suggestions for improving this document, please them to: Contents 1 Connecting to DOE Linux Machines with PuTTY Download and Setup PuTTY Configure PuTTY with DOE Connection Settings Start an SSH Session Setting up a VNC Session Creating Your VNC Password Changing the Default Desktop Environment and Other Settings Creating a New VNC Session Listing Your VNC Sessions Killing a VNC Session Adding an SSH Tunnel for Your VNC Session Find an Available Port to Use For Tunneling Add an SSH Tunnel to Your VNC Port Using a VNC Viewer to Access the VNC Session Download, Install, and Run a VNC Viewer Launch PuTTY and Log In to the server Open the VNC Session Adding and using SSH Tunnels for RDP (Windows machines) Adding the Tunnel Connecting to the Remote Machine Page 1 of 13

2 1 Connecting to DOE Linux Machines with PuTTY 1.1 Download and Setup PuTTY 1. If you do not already have PuTTY installed on your computer, then go to the following link, download and install a copy of PuTTY (on Windows OS, I recommend using the Installer executable). sgtatham/putty/download.html 1.2 Configure PuTTY with DOE Connection Settings 1. The easiest way to configure PuTTY is to download the Windows registrey keys available from my website, here. (If this link is broken let me know.) This file is configured for a connection to borr, you should modify the server name to the one you want. The servers are: borr, odin, and thor. Alternatively, in PuTTY set the Host Name, Port, and Connection Type to those shown in figure 1, but use the server name you want. Then save these settings by typing a name in the Saved Sessions field (the instructions assume it was doe ) and click Save. You can then skip the remaining steps in section Find where you saved the file and double-click it, this should automatically add the keys to your Windows Registry. The next time you run PuTTY there should be a saved session named doe (see figure 1). 3. Load all the settings for the saved session by selecting the name and click Load. 1.3 Start an SSH Session 1. At the bottom of the Sessions setup page, click Open. 2. If this is the first time logging in to this server, you may be asked to add a security key for it; choose Yes to store the key and you will not get this warning next time. 3. A command prompt should pop up. Enter your DOE username and password at the prompts. 2 Setting up a VNC Session This section describes how to use your local Windows machine to set up a remote VNC session that runs on the DOE Linux machines. The advantage of using VNC is that the session remains running even after the connection to it has closed (i.e. your applications remain open even after you close the VNC viewer). Page 2 of 13

3 Figure 1: An example of PuTTY with saved sessions, showing the doe saved session. Page 3 of 13

4 Note: I have tried to stick to the following conventions related to using terminal commands: when asked to enter something at the prompt, this means type it and then push Enter or Return on the keyboard; when directed to type something, this means to type it, but omit the Enter or Return. 2.1 Creating Your VNC Password The first and most important thing to do is create a password (not only for your own protection, but anyone else who uses the machine). 1. At the prompt, enter vncpasswd. You will be directed to enter the password (no characters get echoed to the terminal while you enter your password), and then enter it again to verify against any typos. 2. If everything worked fine, you will be back at the prompt and your VNC session logins are now secured with a password. An example: borr ( tpepler ): ~ $vncpasswd Password : Verify : borr ( tpepler ): ~ $ 2.2 Changing the Default Desktop Environment and Other Settings Note: you may now be able to skip this section, as the xstartup script seems to be created with all the useful defaults now. However, I have left this section in, just in case. If you have never run VNC before, then your xstartup script will not exist in your.vnc directory yet. In that case, skip to section 2.3 to make a dummy session causing the creation of your xstartup file, then section 2.5 to kill the session, then return here to change some of the default settings. 1. To get the gnome desktop environment to load when you create your VNC session, uncomment the two lines at the top of the xstartup script just after the comment Uncomment the following two lines for normal desktop. Use any text editor to do this, but the easiest might be: nano ~/.vnc/xstartup, you can replace nano in the command with vi, gedit, or your own preferred editor. 2. While you ve got the xstartup script open, you may as well make another change. To allow copy/paste from the VNC viewer window to the client (e.g. Windows) machine, add the line vncconfig -nowin & before the two lines you just uncommented. In general, for vncconfig to work it must be called before the desktop environment startup (in this case, before those two lines). Page 4 of 13

5 3. Save the file. Your xstartup should now look similar to this: #!/ bin /sh # allow copy / paste, but do not pop up a window : vncconfig - nowin & # Uncomment the following two lines for normal desktop : unset SESSION_ MANAGER exec / etc / X11 / xinit / xinitrc [ -x / etc / vnc / xstartup ] && exec / etc / vnc / xstartup [ - r $HOME /. Xresources ] && xrdb $HOME /. Xresources xsetroot - solid grey # xterm - geometry 80 x ls - title $VNCDESKTOP Desktop " & 2.3 Creating a New VNC Session 1. Everything should now be set up, so start a new VNC session with a specific resolution and colour depth as follows (note: 24-bit colour is required for some CAD programs, e.g.: Cadence Virtuoso): borr ( tpepler ): ~ $vncserver - depth 24 - geometry 1920 x1080 New borr. doe. carleton.ca :9 ( tpepler ) desktop is borr. doe. carleton.ca :9 Starting applications specified in / home / tpepler /. vnc / xstartup Log file is / home / tpepler /. vnc / borr. doe. carleton.ca :9. log borr ( tpepler ): ~ $ 2. The first line that is printed by the vncserver program tells you which server and display number is associated with this new VNC session. In the example above, the server is borr.doe.carleton.ca and the display is 9. Take note of these, as you will need them to connect using your VNC viewer or when creating an SSH tunnel. 2.4 Listing Your VNC Sessions 1. The vncserver program maintains a set of files in your.vnc directory for each VNC session you have created. Currently running sessions are the files with a.pid extension, so to list your currently running sessions type ls ~/.vnc/*.pid. e.g.: Page 5 of 13

6 borr ( tpepler ): ~ $ls ~/. vnc /*. pid / home / tpepler /. vnc / loki :3. pid / home / tpepler /. vnc / borr. doe. carleton.ca :11. pid / home / tpepler /. vnc / loki :4. pid / home / tpepler /. vnc / borr. doe. carleton.ca :9. pid / home / tpepler /. vnc / loki :6. pid / home / tpepler /. vnc / oslo. doe. carleton.ca :1. pid borr ( tpepler ): ~ $ 2.5 Killing a VNC Session From time to time, you may need to close your VNC session (e.g. a program has locked up and you can t recover). To do this, you need to know the server and VNC display number. 1. SSH in to the server using PuTTY, as outlined in section 1.3. You must be SSH d (or logged in somehow) to the server with the VNC session you want to kill. 2. Now issue the command vncserver -kill :<display number to kill>. For example, if I wanted to kill my borr:11 session: borr ( tpepler ): ~ $vncserver - kill :11 Killing Xvnc process ID 7881 borr ( tpepler ): ~ $ 3 Adding an SSH Tunnel for Your VNC Session This section describes how to use an SSH tunnel to access your VNC session from outside the DOE network (e.g. somewhere else on campus, or off campus completely). 3.1 Find an Available Port to Use For Tunneling 1. On your Windows machine, open cmd.exe by: (a) Using the Start menu search to find a program called cmd.exe ; or (b) type [Windows key]+r to open a run dialog, and enter cmd. 2. At the cmd prompt enter netstat -ano find <port_number>". For the <port_number> you can put any number, but I suggest sticking to 4-digit numbers; 1234 seems to be open on most systems. 3. If the command returns nothing, then the port is available for your use (make a note of the number to use in a later part of the instructions). If the port is already being Page 6 of 13

7 used, the command will return some information about the port. An example of the command first for an unused port number, then a used port number are shown in figure 2. Figure 2: Example of finding an open ( 1234 ) and used ( 1972 ) port. 3.2 Add an SSH Tunnel to Your VNC Port 1. If you have the PuTTY prompt already open, click on the icon in the top left corner of the window (see figure 3) and choose Change Settings..., if you ve just started PuTTY but not opened a connection, make sure you ve loaded the settings for doe first (check that the Host Name and Port fields are set correctly). Either way, you should now see a PuTTY configuration window like that shown in figure On the navigation panel on the left, expand (if needed) Connection, and then SSH, then select Tunnels (you may need to scroll down). 3. In the Source port field, type in the open port you found in section 3.1. In the Destination field type in the port in the format localhost:<port> ; for VNC ports, Page 7 of 13

8 the port number is calculated as [5900] + [display number] (remember the one I told you to note down in section 2.3?). 4. Make sure the Local and Auto radio buttons are selected, then click Add to add this tunnel to the list. See figure 4 for an example. 5. Now select the Session category on the left pane of the PuTTY window, click doe and choose Save to save the setting you just changed (i.e. added a tunnel). 6. Finally, choose Apply at the bottom to apply the changes. Figure 3: The PuTTY window icon to access the Change Settings form. 4 Using a VNC Viewer to Access the VNC Session 4.1 Download, Install, and Run a VNC Viewer Any VNC viewer should work fine, however TigerVNC works best as it allows the session screen size to be dynamically adjusted as you change the viewer window size. Page 8 of 13

9 Figure 4: Adding a new SSH tunnel. Page 9 of 13

10 4.2 Launch PuTTY and Log In to the server If you were following the tutorial so far, PuTTY should already be running and logged into the DOE. Each time you want to access your VNC session (on or off campus), you will have to first launch PuTTY and log in as described in section Open the VNC Session 1. Make sure you have PuTTY running and logged in. 2. Open your VNC viewer, and in the server field enter localhost::<local port>, where <local port> is the Local port you entered in section 3.2, e.g. see figure Finally, click Connect, if you get a warning about this being an unencrypted connection just continue anyway (and you can opt to not have the warning again), next you should be prompted to enter the password that you set earlier, if that works your VNC session should pop up. Figure 5: Entering the server in the VNC Viewer dialog. 5 Adding and using SSH Tunnels for RDP (Windows machines) An alternative to VNC is Remote Desktop Protocol (RDP), and is what you would use to access most machines running the Windows OS, e.g. the VLSI Windows servers maintained by Nagui, or your office computer (if it s running Windows). The corresponding viewer, Remote Desktop Connection, is usually installed by default on Windows; it is also available for Mac OS X, and there are equivalents for Linux (and probably other OSes). The process for using SSH tunnels to allow RDP access is basically the same as for VNC, as shown below. Page 10 of 13

11 5.1 Adding the Tunnel 1. The default port for RDP is 3389 (although this can possibly be changed by the administrator; maybe there s a way to find what it is, please let me know if you find out how). 2. Follow the same steps as in 3.1 and 3.2, except the destination port should be 3389 (or whatever else, if not the default), e.g.: :3389. Note: For the VLSI servers maintained by Nagui, you will have to use the IP address rather than the machine name, as the DNS does not seem to be configured for them. Following is a list of the server names and corresponding IPs: Server IP address Rami Marianne macopeland Tewfik Michel Sobhi Galal Marie eli Mounir gabrielle knight gisele Celine Celine (using IPv6) fe80::716a:8e3e:e63:454b * IPv6 addresses like that shown are only supported in the latest (nightly) builds of PuTTY, and should be included in PuTTY 0.65, when it s released (I assume). You would need to surround the address in square brackets, e.g.: [fe80::1c90:cc21:63ad:da42]:3389. After trying all of that, it was still not working for me, let me know if you have any success. 5.2 Connecting to the Remote Machine 1. Open Remote Desktop Connection, and in the Computer field, type localhost:<local port number>, e.g. if I used port number 2345, that would be localhost:2345 (see figure 6). Page 11 of 13

12 2. Before connnecting, you can adjust display options by clicking Show Options, and then the Display tab (see figure 7). Here you can adjust the screen resolution of the remote session by dragging the slider. You can also use all monitors (if you have more than 1), by checking Use all my monitors... (although this may not work depending on the version of Windows running on the remote machine). As well, you can change the colour depth (24-bit is recommended since some programs cannot run with less). 3. After making any changes, click Connect and you should be prompted to enter your username and password. You have to make sure your username also includes the correct domain, in the format of <domain>\<username>, e.g. vlsi1\tpepler. The VLSI servers use the domain name of vlsi1 while any of the DOE computers have the domain of doe.carleton.ca. Figure 6: Example screenshot of Remote Desktop Connection for a tunnel through local port Page 12 of 13

13 Figure 7: Example screenshot of Remote Desktop Connection display options. Page 13 of 13