TurboVNC Viewer v3.3.1 (build 20251219) [aarch64] Copyright (C) 1999-2026 The VirtualGL Project and many others (see README.md) Visit http://www.TurboVNC.org for more information on TurboVNC USAGE ----- vncviewer [options/parameters] [user@]host [options/parameters] Connect to the specified TurboVNC host using the TurboVNC Session Manager, which uses the TurboVNC Viewer's built-in SSH client to remotely start a new TurboVNC session or to list all sessions running under your user account on the host, allowing you to choose a session to which to connect. The TurboVNC Session Manager requires the TurboVNC Server (v3.0 or later), and by default, it expects the TurboVNC Server to be installed under /opt/TurboVNC on the host. Refer to the TurboVNC User's Guide for more details. vncviewer [options/parameters] host:displayNum [options/parameters] vncviewer [options/parameters] host::port [options/parameters] vncviewer [options/parameters] host::uds_path [options/parameters] Connect directly to the VNC server that is listening on the specified VNC display number, TCP port, or Unix domain socket path on the specified host. This mode of operation does not require the TurboVNC Server. Multiple VNC servers and associated options/parameters can be specified by separating the command-line arguments for each server with --. The TurboVNC Viewer will connect to the VNC servers serially and in the specified order. vncviewer [options/parameters] -listen [port] [options/parameters] Start the TurboVNC Viewer in "listen mode." Refer to the description of the Listen parameter below. Options: -loglevel Set logging level to 0 = errors only 10 = status messages 30 = informational messages (default) 100 = debugging messages 110 = SSH debugging messages 150 = extended input device debugging messages [-config] Read connection information from . A connection info file has an extension of .turbovnc, and each line of the file contains a TurboVNC Viewer parameter name and value separated by an equals sign (=). (Any whitespace before the value is ignored.) If the connection info file has an extension of .vnc, then it is assumed to be a connection info file from TurboVNC 2.2.x and prior, which used a format based on the TightVNC connection info file format. Connection info files will, when opened on Windows or macOS or dragged & dropped onto the TurboVNC Viewer icon, launch the TurboVNC Viewer and initiate a new connection. Parameter values specified in a connection info file override parameter values specified on the command line prior to the connection info file but not parameter values specified on the command line after the connection info file. -?? List rarely-used advanced parameters and their descriptions. Specifying boolean parameters: On: - or -- or =1 or -=1 or --=1 Off: -no or --no or =0 or -=0 or --=0 Parameters that take a value can be specified as: - or -- or = or -= or --= Parameter names and values are case-insensitive (except for hostnames, unencrypted passwords/passphrases, filenames, SSH keys, and usernames.) Default values for all parameters can be specified in /Users/drc/.vnc/default.turbovnc using the connection info file syntax described above. The parameters are: CONNECTION PARAMETERS --------------------- --> Listen Values: 0, 1 (default = 0) Start the viewer in "listen mode." The viewer will listen on port 5500 (or on the port specified by the Port parameter) for reverse connections from a VNC server. To connect a TurboVNC session to a listening viewer, use the vncconnect program on the TurboVNC host. --> Port Values: 0-65535 The TCP port number on which the VNC server is listening. For Un*x VNC servers, this is typically 5900 + the X display number of the VNC session (example: 5901 if connecting to display :1.) For Windows and Mac VNC servers, this is typically 5900. If listen mode is enabled, this parameter specifies the TCP port on which the viewer will listen for reverse connections from a VNC server. (default = 5500) --> RecvClipboard Values: 0, 1 (default = 1) Synchronize the local clipboard with the TurboVNC session's clipboard when the latter changes. --> SendClipboard Values: 0, 1 (default = 1) Synchronize the TurboVNC session's clipboard with the local clipboard when the latter changes. --> Server The VNC server to which to connect. This can be specified in the format {host}[:{display_number}], {host}::{port}, or {host}::{uds_path}, where {host} is the host name or IP address of the machine on which the VNC server is running (the "VNC host"), {display_number} is an optional X display number, {port} is a TCP port, and {uds_path} is the path (which must begin with / or ~) to a Unix domain socket on the VNC host. If no port, Unix domain socket path, or display number is specified, then the viewer will enable the TurboVNC Session Manager, which allows you to remotely start a new TurboVNC session or to choose an existing session to which to connect. When using the Tunnel parameter or the Jump parameter or the TurboVNC Session Manager, an SSH username (default = local username) can be specified by prefixing the VNC host with the username followed by @. In Unix domain socket paths, ~ is expanded to the user's home directory on the VNC host, %h is expanded to the VNC host name (from the point of view of the VNC host), %i is expanded to the numeric user ID on the VNC host, and %u is expanded to the username on the VNC host. When listening on a Unix domain socket, the TurboVNC Server chooses a Unix domain socket path of ~/.vnc/%h_{display_number}.uds by default. --> Shared Values: 0, 1 (default = 1) Request a shared VNC session. When the session is shared, other users can connect to the session (assuming they have the correct authentication credentials) and collaborate with the user who started the session. If this parameter is disabled and the TurboVNC session is using default settings, then you will only be able to connect to the session if no one else is already connected. INPUT PARAMETERS ---------------- --> FSAltEnter Values: 0, 1 (default = 0) Toggle full-screen mode when Alt-Enter is pressed. --> MenuKey Values: F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, Pause, Print, ScrollLock, Escape, Insert, Delete, Home, PageUp, PageDown (default = F8) The key used to display the popup menu --> ReverseScroll Values: 0, 1 (default = 0) Reverse the direction of mouse scroll wheel events that are sent to the VNC server. This is useful when connecting from clients that have "natural scrolling" enabled. --> ViewOnly Values: 0, 1 (default = 0) Ignore all keyboard and mouse events in the viewer window and do not pass those events to the VNC server. DISPLAY PARAMETERS ------------------ --> AcceptBell Values: 0, 1 (default = 1) Produce a system beep when a "bell" event is received from the VNC server. --> CompatibleGUI Values: 0, 1 (default = 0) Expose all compression levels (0-9) in the TurboVNC Viewer Options dialog (useful when connecting to non-TurboVNC servers.) This parameter is effectively set when using any encoding type other than Tight or when selecting a compression level that is not useful for TurboVNC servers. --> CursorShape Values: 0, 1 (default = 1) Normally, the TurboVNC Server and compatible VNC servers send only changes to the remote mouse cursor's shape and position. This results in the best mouse responsiveness. Disabling this parameter causes the server to instead render the mouse cursor and send it to the viewer as an image every time the cursor moves or changes shape. Using a remotely rendered cursor can increase network "chatter" between host and client significantly, which may cause performance problems on slow networks. --> DesktopSize Values: WxH, W0xH0+X0+Y0[,W1xH1+X1+Y1,...], Auto, or Server (default = Auto) If the VNC server supports remote desktop resizing, then attempt to resize the remote desktop to the specified size (example: 1920x1200) or reconfigure the server's virtual screens with a specified layout (example: 1920x1200+0+0,1920x1200+1920+0). Setting this parameter to "Auto" causes the remote desktop to be resized to fit in the viewer window without using scrollbars, and it causes the server's virtual screens to be reconfigured such that their screen boundaries align with the client's screen boundaries when the viewer window is in its default position. Setting this parameter to "Server" or "0" disables remote desktop resizing and uses the desktop size and screen configuration set by the server. --> FullScreen Values: 0, 1 (default = 0) Start the viewer in full-screen mode. --> Scale Values: 1-1000, Auto, or FixedRatio (default = 100) Reduce or enlarge the remote desktop image. The value is interpreted as a scaling factor in percent. The default value of 100% corresponds to the original remote desktop size. Values below 100 reduce the image size, whereas values above 100 enlarge the image proportionally. If this parameter is set to "Auto", then automatic scaling is performed. Automatic scaling reduces or enlarges the remote desktop image such that the entire image will fit in the viewer window without using scrollbars. If this parameter is set to "FixedRatio", then automatic scaling is performed, but the original aspect ratio is preserved. Enabling automatic scaling disables automatic desktop resizing. --> Span Values: Primary, All, Auto (default = Auto) Multi-screen spanning mode Values: "Primary" = The viewer window should span only the primary monitor. "All" = The viewer window should span all monitors. "Auto" = The viewer window should span all monitors only if the window cannot fit on the primary monitor. When using automatic desktop resizing, "Auto" has the same effect as "Primary" when in windowed mode and the same effect as "All" when in full-screen mode. This parameter has no effect on macOS unless "Displays have separate Spaces" is disabled in the system settings. --> Toolbar Values: 0, 1 (default = 1) Show the toolbar by default. ENCODING PARAMETERS ------------------- --> CompressLevel Values: 0-9 (default = 1) When Tight encoding is used, the compression level specifies the amount of zlib compression to apply to subrectangles encoded using the indexed color, mono, and raw subencoding types. If the JPEG subencoding type is enabled, then the compression level also defines the "palette threshold", or the minimum number of unique colors that a subrectangle must have before it is encoded using JPEG. Higher compression levels have higher palette thresholds and thus favor the use of indexed color subencoding, whereas lower compression levels favor the use of JPEG. Compression Level 1 is usually the default when JPEG is enabled, because extensive experimentation has revealed little or no benefit to using higher compression levels with most 3D and video workloads. However, v1.1 and later of the TurboVNC Server also supports Compression Level 2 when JPEG is enabled. Compression Level 2 can reduce the network usage of certain types of low-color workloads by about 20-40% (with a commensurate increase in CPU usage.) In v1.2 or later of the TurboVNC Server, compression levels 5-7 map to compression levels 0-2, but they also enable interframe comparison in the server. Interframe comparison maintains a copy of the remote framebuffer for each connected viewer and compares each framebuffer update with the copy to ensure that redundant updates are not sent to the viewer. This prevents unnecessary network traffic if an ill-behaved application draws the same thing over and over again, but interframe comparison also causes the TurboVNC Server to use more CPU time and much more memory. --> Encoding Values: Tight, ZRLE, Hextile, Raw (default = Tight) Preferred RFB encoding type to use. If the server does not support the preferred encoding type, then the next best one will be chosen. There should be no reason to use an encoding type other than Tight when connecting to a TurboVNC session, but this parameter can be useful when connecting to other types of VNC servers, such as RealVNC. --> JPEG Values: 0, 1 (default = 1) Enable the JPEG subencoding type when using Tight encoding. This causes the Tight encoder to use JPEG compression for subrectangles that have a high number of unique colors and indexed color subencoding for subrectangles that have a low number of unique colors. If this parameter is disabled, then the Tight encoder will select between indexed color or raw subencoding, depending on the size of the subrectangle and its color count. --> Quality Values: 1-100 (default = 95) JPEG quality to use when compressing JPEG images with the Tight+JPEG encoding methods. Lower quality values produce grainier JPEG images with more noticeable compression artifacts, but lower quality values also use less network bandwidth and CPU time. The default value of 95 should be perceptually lossless (that is, any image compression artifacts it produces should be imperceptible to the human eye under most viewing conditions.) --> Subsampling Values: 1X, 2X, 4X, Gray (default = 1X) Chrominance subsampling level to use when compressing JPEG images with the Tight+JPEG encoding methods When compressing an image using JPEG, the RGB pixels are first converted to the YCbCr colorspace, a colorspace in which each pixel is represented as a brightness (Y, or "luminance") value and a pair of color (Cb and Cr, or "chrominance") values. After this colorspace conversion, chrominance subsampling can be used to discard some of the chrominance components in order to save bandwidth. Values: "1X" = Retain the chrominance components for all pixels (best image quality but highest network and CPU usage.) "2X" = Retain the chrominance components for every other pixel. "4X" = Retain the chrominance components for every fourth pixel (typically implemented as 2X subsampling in both X and Y directions.) "Grayscale" = Discard all chrominance components, leaving only luminance. 2X and 4X subsampling typically produce noticeable aliasing of lines and other sharp features, but with photographic or other "smooth" image content, it may be difficult to detect any difference between 1X, 2X, and 4X. --> Samp Alias for Subsampling SECURITY AND AUTHENTICATION PARAMETERS -------------------------------------- --> Jump Tunnel the VNC connection through the specified SSH server ("jump host") as well as through the SSH server running on the VNC host. The jump host can be specified in the format [{ssh_user}@]{jump_host}[:{ssh_port}], where {ssh_user} is the SSH username on the jump host (default = local username) and {ssh_port} is the TCP port on which the jump host's SSH server is listening (default = the default value of the SSHPort parameter.) This parameter is functionally equivalent to the ProxyJump OpenSSH configuration keyword. When using this parameter, the VNC host should be specified from the point of view of the jump host. For Unix domain socket connections, this parameter is equivalent to the Via parameter. For TCP connections, this parameter creates a multi-level SSH tunnel to the VNC host, which ensures that the VNC connection is encrypted on the server-area network and eliminates the need to open RFB ports in the VNC host's firewall. The Via parameter, by comparison, creates an SSH tunnel to the gateway host and forwards the RFB/TCP connection directly to the VNC host from the gateway host. When using the built-in SSH client, this parameter and the ProxyJump OpenSSH configuration keyword do not allow multiple comma-separated SSH hops to be specified. --> J Alias for Jump (for compatibility with OpenSSH) --> LocalUsernameLC Values: 0, 1 (default = 0) When the SendLocalUsername parameter is set, or when using SSH tunneling without a specified SSH username, convert the local username to lowercase before using it for authentication. This may be useful with Windows clients, since Windows allows mixed-case usernames but Un*x and Mac systems generally don't. --> NoUnixLogin Values: 0, 1 (default = 0) Disable Unix Login authentication when connecting to TightVNC-compatible servers and Plain authentication when connecting to VeNCrypt-compatible servers. Setting this parameter effectively removes "Plain" (and its encrypted derivatives) and "UnixLogin" from the value of the SecurityTypes parameter. This is useful if the server is configured to prefer a security type that supports Unix Login/Plain authentication and you want to override that preference for a particular connection (for instance, to use a one-time password.) --> SecurityTypes (default = X509Plain,X509Vnc,X509None,TLSPlain,TLSVnc,TLSNone,VNC,Plain,UnixLogin,None) A comma-separated list of the security types that can be used if the server supports them. "VNC" and "None" are the standard VNC password and no-password authentication schemes supported by all VNC servers. The seven supported VeNCrypt security types ("Plain", "TLSNone", "TLSVnc", "TLSPlain", "X509None", "X509Vnc", and "X509Plain") are combinations of three encryption methods (None, Anonymous TLS, and TLS with X.509 certificates) and three authentication schemes (None, Standard VNC, and Plain.) The "UnixLogin" security type enables user/password authentication using the TightVNC security extensions rather than VeNCrypt. "Plain" and "UnixLogin" authenticate using a plain-text username and password, so it is strongly recommended that those types be used only with TLS encryption or SSH tunneling. The order of this list does not matter, since the server's preferred order is always used. When using the TurboVNC Session Manager, this parameter is effectively set to "VNC" unless the SessMgrAuto parameter is disabled. --> SendLocalUsername Values: 0, 1 (default = 0) When using user/password authentication schemes (Unix Login, Plain), authenticate using the local username rather than prompt for a username. As with the User parameter, setting this parameter effectively disables any authentication schemes that don't require a username. --> SSHConfig (default = /Users/drc/.ssh/config) Path to an OpenSSH configuration file to use with the built-in SSH client. If specified on the command line or in a connection info file, TurboVNC Viewer parameters take precedence over the OpenSSH configuration file. --> F Alias for SSHConfig (for compatibility with OpenSSH) --> SSHKey When using the built-in SSH client with the publickey SSH authentication method, this parameter specifies the text of an SSH private key to use when authenticating with the SSH server. You can use \n within the string to specify a new line. --> SSHKeyFile When using the built-in SSH client with the publickey SSH authentication method, this parameter specifies a file that contains an SSH private key (or keys) to use when authenticating with the SSH server. This parameter and the SSHKey parameter behave like the OpenSSH -i option and IdentityFile configuration keyword. The SSH client will attempt to use the following private keys, in order, when authenticating with the SSH server: 1. Any key specified with this parameter or the SSHKey parameter, if the key is already provided by the SSH agent (ssh-agent or Pageant) or a valid passphrase is supplied for the key using the SSHKeyPass parameter 2. Any key specified with the IdentityFile OpenSSH configuration keyword, if the key is already provided by the SSH agent 3. Any other keys provided by the SSH agent, in the order provided 4. Any key specified with this parameter, the SSHKey parameter, or the IdentityFile OpenSSH configuration keyword, if a valid passphrase is not supplied for the key 5. /Users/drc/.ssh/id_rsa, /Users/drc/.ssh/id_ecdsa, /Users/drc/.ssh/id_ed25519, and /Users/drc/.ssh/id_dsa (in that order), if this parameter, the SSHKey parameter, and the IdentityFile OpenSSH configuration keyword are not specified --> i Alias for SSHKeyFile (for compatibility with OpenSSH) --> SSHKeyPass When using the built-in SSH client with the publickey SSH authentication method, this parameter specifies the passphrase for the SSH key(s) specified with the SSHKey or SSHKeyFile parameter. --> SSHPort Values: 0-65535 (default = 22) When using the built-in SSH client, this parameter specifies the TCP port on which the VNC host's or gateway host's SSH server is listening. This parameter does not apply to jump hosts. --> p Alias for SSHPort (for compatibility with OpenSSH) --> Tunnel Values: 0, 1 (default = 0) Tunnel the VNC connection through the SSH server running on the VNC host. When using the TurboVNC Session Manager, this parameter is effectively set unless the SessMgrAuto parameter is disabled or the Jump parameter is specified. This parameter is effectively set if the Server parameter specifies a Unix domain socket connection to a remote host. --> User The username to use for Unix Login authentication (TightVNC-compatible servers) or Plain authentication (VeNCrypt-compatible servers.) Specifying this parameter effectively removes any types from the value of the SecurityTypes parameter except for "Plain" (and its encrypted derivatives) and "UnixLogin", thus allowing only authentication schemes that require a username. --> X509CA (default = /Users/drc/.vnc/x509_ca.pem) X.509 Certificate Authority certificate to use with the X509* security types. This is used to check the validity of the server's X.509 certificate. --> X509CRL (default = /Users/drc/.vnc/x509_crl.pem) X.509 Certificate Revocation List to use with the X509* security types. This is used to check the validity of the server's X.509 certificate.