UltraVNC

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UltraVNC

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Screenshot
Screenshot of the connection dialog of the UltraVNC Viewer.
Basic data

developer Rudi De Vos, UltraSam, Martin Scharpf, Oliver Schneider
Publishing year June 24, 2006
Current  version 1.2.2.4
(March 14, 2019)
operating system Windows
programming language C , C ++ and Java
category remote maintenance
License GPLv2 +
German speaking Yes
www.uvnc.com

UltraVNC (even Ultr @ VNC , UVNC ) is a VNC - Software for Windows and is used for remote maintenance of computers. In addition to all VNC functions, Ultravnc also implements significantly more efficient compression algorithms as well as very close-to-the-system and therefore powerful techniques for intercepting the server screen ( grabbing ). UltraVNC uses special Windows services and therefore offers - apart from a Java viewer - only client / server software for Windows operating systems.

UltraVNC is programmed in the programming language C ++ . The platform-independent UltraVNC Java client applet is programmed in Java . UltraVNC runs on all Windows versions from Windows 95 to Windows 10 and is developed under the GPL .

backgrounds

With the help of an UltraVNC viewer ( client ) one is able to access an UltraVNC server (via TCP / IP ) and to make entries and changes on this remote computer in order to receive the screen output from it in return. In this way, the viewer using the viewer program gains the impression of sitting directly in front of the remote computer ("remote").

Functional scope of the program package

UltraVNC Viewer on Windows 7 with an active connection to an UltraVNC server, which runs on a system with Windows XP. The file transfer and text chat functions are also shown.
One of the configuration dialogs of the UltraVNC server. The many configuration options are outstanding, cf. with other VNC servers.

In principle, the UltraVNC viewer can also contact other VNC servers and the UltraVNC server can also be contacted by other VNC viewers. In this case, however, only the basic functions (control of mouse and keyboard as well as reception of the screen content) are available and not the full range of functions of the program, namely in detail:

  • File transfer function - It can transfer files with its own file manager in the two-window technology to be replaced. The user can decide individually whether files should be copied to the remote PC or a file should be fetched from the remote computer. If the encryption plug-in is installed, it will also encrypt file transfers.
  • Text-based chat function - ideal for communication between the users involved via an existing VNC connection.
  • RFB protocol support - From version 1.0.9.x onwards, UltraVNC supports the remote framebuffer protocol version 3.8, which is supported by many VNC derivatives.
  • Different authentication methods - A password is required to access the server. This is only encrypted in the first eight DES digits . There is also the option of using the MS-Logon-I procedure for NT domains. In addition, the MS-Logon-II procedure for the connection to a directory service, such as. B. Microsoft Active Directory , possible. Due to the possibility of authentication via MS Logon I and II, the respective user administration can be used with its corresponding groups and user rights.
  • Encryption of the connection with an individual key - With the help of the modular integration of the free DSM plugins, secure RC4 or AES encryption can be generated between UltraVNC server and viewer up to a key length of 128-bit in UltraVNC. The RC4-DSM plug-in is installed during the UltraVNC installation. The RC4-DSM plug-in enables e.g. B. the creation of an individual rc4.key file, which must be available on the UltraVNC server and UltraVNC viewer so that encryption is possible. The new DSM encryption plug-in from Adam Walling has been installed since UltraVNC version 1.0.9.5 and newer. When using UltraVNC, this can use asymmetrical encryption of up to RSA 3072 bit and use AES 256 bit for symmetrical encryption. Other symmetric encryptions can also be configured. If the SecureVNC-DSM plug-in is activated in the administrative settings via the UltraVNC server, 2048-bit RSA and 256-bit AES encryption is set up on the basis of a hash value generated by the VNC standard password without any further configuration.
  • Support for multiple clients - The UltraVNC server signals can be picked up by an almost arbitrary number of "viewers" and displayed. This feature is ideal for training and presentations over the network. This allows students or viewers of the presentation to follow the presentation of the teacher or presenter.
  • Stepless scaling - the server screen can be transferred to the appropriate screen resolution of the viewer by specifying the appropriate option . The scaling is specified in percentages. The scaling setting can also be specified in the options of the requesting UltraVNC viewer.
  • Screen selection - As of UltraVNC 1.0.9.5 and newer, on PCs with several monitors it can be specified in the UltraVNC viewer on which monitor the remote access is to be displayed or output.
  • Graphic toolbar - The graphic toolbar can be used to call up or initiate a large number of routine activities during a connection.
  • TAB viewer functionality - The TAB viewer, also known as DirectX viewer , was part of the regular installation routine. It requires considerably more resources than the regular UltraVNC viewer. The TAB viewer enables the monitoring of several UltraVNC servers with only one program at the same time. Only one tab is opened in the TAB viewer for each connection session to a remote PC. The TAB viewer can be set in such a way that it saves a * .vnc configuration file in a temporary subdirectory of the TAB viewer for each existing connection when the TAB viewer is closed and automatically calls, processes and processes these configuration files when the TAB viewer is restarted re-establishes the corresponding connections without specifying the individual options and the respective passwords. This module is currently not being further developed.
  • Server screen can be locked - In the options, you can enter whether the user sitting in front of the UltraVNC server is allowed to make entries with the mouse and keyboard. This function is provided with an icon in the toolbar and can be easily activated or deactivated. With the help of this function one wants to increase the attention of the user who is sitting in front of the UltraVNC server.
  • JavaViewer with file transfer function - If the client browser does not have a VNC viewer, but a browser with the latest JRE is installed, an applet provided by the UltraVNC server can be used as a client, although it only provides the basic client functions.
  • Integration as a service in the system - UltraVNC can be installed as a system service on all Windows NT operating systems . This means that access to a logged off Windows system is also possible via UltraVNC. This also ensures that users without administrator rights cannot deactivate remote access.
  • Mirror driver - The UltraVNC mirror driver is installed on the remote computer as a video driver so that it simulates a graphics card for the Windows installation . This means that the screen contents can already be accessed at the kernel space level, which considerably reduces the CPU load on the UltraVNC server.
  • SingleClick version - On the basis of UltraVNC, it is possible to configure a scaled-down and optimized UltraVNC server in such a way that when it is executed, it tries to reach a viewer in listen mode via the Internet or in the LAN . It is a single executable file that is ideally used to provide an easy way for customers to contact customer service if they have software problems.
  • Individual, selected desktop windows can be transmitted - In order to reduce the necessary transmission bandwidth and to increase the viewer's attention to the essentials, it is possible to transmit only individual desktop windows and not the entire screen. This option can be entered and activated with a mouse click in the toolbar or in the server module.
  • INI configuration file - In version 1.0.3 and higher, it is no longer necessary to configure the UltraVNC server via the Windows registry . This task is carried out by a special ultravnc.ini file, which must be located in the same directory as the server. The installation program contains an independent program to create an optimal configuration file with all possible options. This program is called uvnc_settings . If changes are made to the ultravnc.ini file, which can be done via the administrative settings of the UltraVNC server or via the uvnc_settings tool, the user must have the appropriate user rights.
  • Portable application - Both program components, UltraVNC viewer and server, can also be used without installation. They are therefore also suitable for starting from a USB stick.

criticism

The weak point of UltraVNC is the storage of the access password, which is only encrypted with DES . With this encryption developed by IBM in the 1970s , only the first eight characters are encrypted with a maximum of 56 bits. Each additional character of a password is coded unencrypted. Password encryption and the associated security cannot be improved directly as it is a legacy from the design of the remote framebuffer protocol ; H. is so defined in its specification. This deficiency can be eliminated by using the new DSM encryption extension from Adam Walling.

literature

Individual evidence

  1. ↑ Downloads and changes from UltraVNC on the UltraVNC website
  2. ↑ a b SecureVNC

Web links

Commons : UltraVNC  - collection of pictures, videos and audio files