Method of controlling access for software development via a virtual common desktop with plural viewers

[0001] This invention relates generally to computer networks and is particularly directed to the exercise of control over viewer access to a common desktop computer for the purpose of sharing control of software applications in a virtual network computing arrangement.

[0002] Virtual network computing (VNC) enables multiple users at different locations to share a common desktop computer for the purpose of sharing control of software applications. VNC allows two users at different locations to view the same desktop and exercise control over the software applications that were started in the shared desktop. Within the shared desktop, each user is able to observe the mouse and keyboard actions of all other participating users as changes are made to the software application. VNC has proven to be a useful tool during design/debug sessions where each participant brings his or her own expertise to the debug process. For example, one participant may bring to the session hardware simulation expertise, while another participant may contribute software expertise in debugging a software application. VNC is also useful in updating documentation created by multiple authors. Each author, while at his or her own work station, can update the same document, while reviewing the updates of other contributing authors. The ability to share a desktop at remote locations is thus extremely useful and efficient in the development of software applications in terms of saving time, money and travel, as the participating users do not have to be physically present at one location to share the desktop computer.

[0003] In general, VNC employs two components: a server and a viewer. The server runs on a host machine which includes a desktop and is started by a user located at the host machine. A viewer uses a remote machine, with a viewer session started by a user at the remote machine. The user that initially starts the server is the server owner. All activity in the desktop is done using the computer ID of the server owner. Viewers that subsequently connect into the session are provided active access. All active viewers have the same control over applications within a given server and are run under the computer ID of the server owner.

[0004] A server owner must be alert to the activities of the other viewers participating in the shared desktop. Because all active viewers can start, stop and control software applications as if these inputs originated with the server owner, it is highly desirable to exercise security measures to protect the applications from unauthorized operations of other viewers. While current VNC versions allow multiple users to share a desktop, none protect a server owner from unauthorized users exploiting the desktop's server when their activities are not being observed by the server owner.

[0005] The present invention addresses the aforementioned limitations of the prior art by allowing the server owner of a VNC arrangement to dynamically assign each VNC viewer either passive status wherein the viewer may only observe the desktop activities of other viewers or active status wherein the viewer may exercise control over a software application.

[0006] The present invention contemplates a VNC arrangement which allows multiple users, or viewers, to share a desktop computer with the extent of access of each viewer determined by the server owner. The server owner creates an “VNCSESSION”, which the server owner owns and which is comprised of a server and a viewer for the server owner. The IP address of each subsequent viewer is compared to the contents of a file provided by the session owner to determine if the viewer is to be accorded “passive” or “active” status. If the viewer's IP address is stored in the file, the viewer is accorded active status and is allowed to initiate activity in the desktop such as making changes to software applications in the desktop. If the viewer's IP address is not present in the file the viewer is accorded only passive status, limiting the viewer's participation to merely observing the actions of other active viewers including the actions of the session owner. The present invention allows the session owner to create and maintain access control to the desktop's server on a per viewer and per session basis. Information such as the IP address, logical machine name of a VNC viewer which connects to the desktop, and connected viewer status (active/passive) is provided on a video display for viewing by the session owner. Also presented on the video display for viewing by the session owner is such information as when a viewer disconnects from the desktop and the number of viewers connected to the desktop from a given IP address. The present invention allows the session owner to use the video display to change the status of any connected viewer, and further provides auditing and VNC logfile monitoring of the desktop server for errors and insensitivities and notifies the session owner when problems are detected. An audio “beep” is also provided to notify the session owner whenever a viewer connects or disconnects from the VNC session.

[0015] Referring to FIG. 1, there is shown in simplified combined schematic and block diagram form a virtual network computing (VNC) system 10 in which the present invention is intended for use. VNC system 10 includes first, second, third and fourth desktop computers 14, 16, 18, and 20. While the VNC system 10 is shown as including four desktops, the VNC system with which the present invention is intended for use may incorporate virtually any number of desktop computers. Each desktop computer includes a video display, or monitor, and a central processor unit, as is conventional. Each of the desktop computers also includes a server, where a server 12 of the first desktop computer 14 is shown in FIG. 1. It is on the first desktop computer 14 that a VNCSESSION is initiated by the operator of the first desktop computer, who is hereinafter referred to as the “session owner”. Server 12 is typically incorporated in the first desktop computer 14, but is shown as a separate block in FIG. 1 to illustrate that the second, third and fourth desktop computers 16, 18 and 20 gain access to the VNCSESSION through the server 12 of the first desktop computer 14.

[0016] Referring to FIG. 2, there is shown a conceptional illustration in block diagram form of the dynamic Internet Protocol (IP)-based control of virtual computing applications of the present invention. Each of the blocks shown in FIG. 2 represents either a software application or a data file of the VNC system. The figure shows the relationship between the various software applications and files in carrying out the dynamic IP-based control of virtual computing applications of the present invention.

[0017] VNCSESSION 30 is a software application employed by a user wishing to start an interactive desktop session. In the following description, the terms “user” and “viewer” are assigned the same meaning and are used interchangeably. VNCSESSION 30 creates the server and VNC session owner's viewer on the same desktop, or machine. The user wishing to start the interactive desktop session is the owner of the desktop and is also termed hereinafter as the owner of the VNCSESSION. The owner of the VNCSESSION 30 determines the desktop password for accessing the VNC session as well as the access mode, either active or passive, for each of the VNCVIEWERS 32 and 34 who connect to the desktop. FIG. 2 shows only two VNCVIEWERS 32 and 34, however, the dynamic IP-based control of virtual computing applications of the present invention may be utilized with virtually any number of viewers, or users. VNCVIEWERS 32, 34 connected to the desktop operate in the session owner's desktop under the user identification (USERID) of the VNCSESSION owner.

[0018] The organization of the software applications and data files shown in FIG. 2 will now be further described with respect to FIGS. 3–6, which are simplified flow charts illustrating the series of steps carried out in each of the software applications shown in FIG. 2.

[0019] With reference also to FIG. 3, there is shown a simplified flow chart illustrating the sequence of steps involved in implementing a viewer interactive desktop VNCSESSION 30 in accordance with the principles of the present invention. After invoking VNCSESSION, the session owner is first offered the opportunity to specify the VNCSESSION password to be used for gaining access to the desktop. Thus, the VNCSESSION application is initiated by the session owner at step 60, followed by a determination by the program of the existence of a password at step 62. If the session owner has previously selected and entered a password, the program proceeds to step 64 and permits the session owner to change the password, if desired, by proceeding to step 66. If a password has not previously been selected and entered by the session owner, the program proceeds from step 62 to step 66 and permits the session owner to create a password. In either case, the program then proceeds to step 68 and creates the VNCSERVER application 36 which, in turn, creates the security enhanced XVNC application 38 which is shown in FIG. 6 and described in detail below.

[0020] The VNCSESSION application also creates a VNCVIEWER session 40 at step 70 for the session owner, which establishes a connection to VNCSERVER 36. Termination of the session owner's VNCVIEWER 40 results in termination of all initiated processes, and particularly the XVNC application, and an end to the VNCSESSION. Terminating all initiated processes prevents unauthorized user access to the VNCSESSION 30. In addition to creating the VNCSERVER and XVNC applications, VNCSESSION also creates a VNCDAEMON application 44 and a VNC Access Control Panel application 46 as shown in FIG. 2. VNCDAEMON 44 monitors for VNCVIEWERS requesting to establish connection with the VNCSESSION. This monitoring is done by reading entries in a log file 42 posted by the XVNC application 42. More specifically, VNCDAEMON 44 looks for VNCVIEWER connect and disconnect messages. When these messages are generated, VNCDAEMON 44 signals the Access Control Panel 46 to update a Graphical User Interface (GUI) display based on VNCVIEWER activity as described below.

[0021] The Access Control Panel application 46 provides and maintains the GUI display shown in FIGS. 7 and 8 for the VNC session owner indicating status of VNCVIEWERS 32, 34 which have connected or disconnected from the VNC session. The VNCSESSION owner uses the GUI display to select the connection mode for each connected VNCVIEWER. The connection mode choices are either active or passive. If a connecting VNCVIEWER is provided active status, its Internet protocol (IP) address is stored in an access control file 48 by the Access Control Panel application 46. The security enhanced XVNC application 38 monitors the access control file 48 for added and deleted IP addresses. When an IP address is added to the address control file 48, the VNCVIEWER application associated with it is automatically provided with an active status. If an IP address is removed, or deleted, from the access control file 48, the VNCVIEWER application associated with the deleted IP address is changed from active to passive status. An active VNCVIEWER can observe as well as initiate activity in the VNCSESSION desktop. A passive VNCVIEWER can merely observe the activity of other viewers in the VNCSESSION.

[0022] After the VNCDAEMON application 44 is created as step 72, VNCSESSION proceeds to step 74 and executes a continuing loop in waiting for the session owner's viewer to terminate the VNC session. After the session owner's viewer terminates the VNC session as detected at step 74, the program proceeds to step 76 for terminating the VNCSERVER application which ends the VNC session. The program then proceeds to step 78 for cleaning up the VNCSESSION application, including terminating the VNCDAEMON application. This is followed by termination of the VNCSESSION application at step 80.

[0023] Referring to FIG. 4, there is shown a simplified flow chart illustrating the steps involved in the VNCDAEMON application. As indicated earlier, the VNCDAEMON application is invoked by the VNCSESSION application at step 72. The VNCDAEMON application is started at step 90, and proceeds to step 92 for creating the access control panel procedure for presenting the access control panel 46 on the GUI for use by the VNCSESSION owner. After creating the access control panel, the VNCDAEMON application proceeds to step 94 for reading the content of the XVNC log file 42. The VNCDAEMON application then proceeds to step 96 for monitoring for VNCVIEWER connect or disconnect messages from the log file 42. The VNCDAEMON application then executes a loop looking for a VNCVIEWER connect or disconnect message until a connect or disconnect message is detected at step 96, whereupon the VNCDAEMON application proceeds to step 98 for parsing the connect or disconnect message. At step 98, the VNCDAEMON application processes the message to determine if it is a connect or disconnect message and then proceeds to step 100 for updating the information presented on the access control panel 46 for the session owner. The VNCDAEMON application then returns to step 94 for again reading the contents of the XVNC log file and again monitoring for VNCVIEWER connect and disconnect messages from the log file 42.

[0024] Referring to FIG. 5, there is shown a simplified flow chart of the steps involved in the access control panel GUI display application which is created by the VNCDAEMON application at step 92. The access control panel GUI display application starts at step 110 and proceeds to step 112 for presenting the GUI display on the session owner's desktop computer. The access control panel GUI display application then proceeds to step 114 and looks for either a VNCDAEMON signal indicating a viewer connect or disconnect or a manual input at the GUI display by the session owner. The access control panel GUI display application executes a loop at step 114 until either a VNCDAEMON signal or a manual display event initiated by the session owner is detected. Once either a VNCDAEMON signal or a manual display event is detected at step 114, the access control panel GUI display application proceeds to step 116 for parsing the signal or event. For example, the application determines if a session owner initiated a manual display event such as assigning an active or inactive status to a viewer. The access control panel GUI display application then proceeds to step 118 for processing the signal or event such as updating the access control file regarding a particular viewer or user. The access control panel GUI display application then at step 120 updates the GUI display in presenting the latest VNCDAEMON signal information or owner initiated manual display event on the GUI display.

[0025] Referring to FIG. 6, there is shown a simplified flow chart illustrating the steps involved in carrying out the security enhanced XVNC application. The security enhancements for the XVNC application start at step 130 and proceed to step 132 for granting WRITE access to the VNCSESSION owner's VNCVIEWER. Thus, the first viewer in the VNC system is designated as the session owner and is provided active status with respect to the software application in the desktop computer. The XVNC application then proceeds to step 134 and monitors for other viewers for connecting to the XVNC. If another viewer request is detected at step 134, the program proceeds to step 136 and provides that viewer with READ access. The XVNC application then proceeds to step 138 for updating an internal copy of the access control file for all VNCVIEWER permissions. If at step 134, the XVNC application does not detect any additional VNC viewer access requests, the program proceeds to step 140. At step 140, the XVNC application looks for VNCVIEWER WRITE requests. If no VNCVIEWER WRITE requests are detected at step 140, the XVNC application loops back to step 134 and again looks for a VNCVIEWER access request. If at step 140, a VNCVIEWER WRITE request is detected, the XVNC application proceeds to step 142 to determine if the access control file has been modified since the file was last reviewed. If the access control file has been modified since last reviewed, the XVNC application proceeds to step 144 and reads the new information into the access control file for updating all VNCVIEWER permissions. If at step 142, it is determined that the access control file has not been modified since last reviewed, the XVNC application proceeds to step 146 to determine if the VNCVIEWER has WRITE permission. If the VNCVIEWER has WRITE permission, the XVNC application proceeds to step 148 and allows the VNCVIEWER to WRITE inputs to the software application which is the subject of the VNCSESSION. If at step 146, it is determined that the VNCVIEWER does not have WRITE permission, the XVNC application proceeds to step 150 and denies WRITE access to the VNCVIEWER. The XVNC application then returns to step 134 for continuing to monitor for VNCVIEWER access requests.

[0026] Referring to FIGS. 7 and 8, there are shown presentations on a GUI display 160 for use by a VNC session owner in monitoring and controlling access to a desktop computer by other viewers, or users, of a VNC session in accordance with one aspect of the present invention. The GUI display 160 includes a File listing which allows for a pull-down menu for viewing the log file, editing the access file, and other control activities exercised by the session owner. The pull-down menu 164 is shown in FIG. 8 below the File listing and includes selections such as View log file, Edit access file, Refresh access display, and Exit VNC session. Below the File listing in the GUI display 160 shown in FIG. 7 are three lines of information for the session owner. These lines include VNC Server Host, VNC log file, and VNC access file. The VNC server host identifies the VNCSESSION computing platform. The VNC log file identifies the directory location of the log file, and the VNC access file identifies the directory location of the access file. Also shown are Master Enable and Master Disable selectors to permit the session owner to activate or deactivate all VNC viewers at the same time. Also shown are indicators regarding the connected viewers such as the IP address, client and number of viewers at that IP address viewing the VNC session. The GUI display 160 further includes ACTIVE and PASSIVE selectors for use by the session owner for providing individual viewers either in active or passive status. Next to the ACTIVE and PASSIVE selectors is the specific machine name of the desktop connected to the VNC session which only appears when the viewer connects to or disconnects from the VNC session. This information is detected and displayed under the control of the VNCDAEMON and access control panel applications as described above.

[0027] There has thus been shown a method for exercising dynamic IP-based control over access of viewers to the server of a shared desktop in a virtual network computing (VNC) system. In the VNC system, multiple users, or viewers, at different locations share a common desktop computer for the purpose of sharing control of software applications on the desktop. The user who opens the VNCSESSION is termed the session owner and is given active access to the software application in terms of exercising control over the application. The session owner determines whether subsequent viewers have active status or passive status, wherein the viewer is permitted to only review desktop activity initiated by other viewers, but cannot initiate such activities themselves, i.e., cannot exercise control over the software application. The session owner can specify on a per viewer basis as well as on a per session basis, the level of access, active or passive, of each subsequent viewer.

[0028] While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant art that changes and modifications may be made without the parting from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description in accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.