x11vnc
x11vnc does not create an extra display (or X desktop) for remote control. Instead, it uses the existing X11 display shown on the monitor of a Unix-like computer in real time, unlike other Linux alternatives such as TightVNC Server.
tightvnc offers better compression and performance options. x11vnc offers better security focus ( can be secured with SSH or SSL.) but it's known to be slower.
However, it is possible to use Xvnc or Xvfb to create a 'virtual' extra display, and have x11vnc connect to it, enabling X-11 access to headless servers.[1]
x11vnc has security features that allows the user to set an access password or to use Unix usernames and passwords. It also has options for connection via a secure SSL link. An SSL Java VNC viewer applet is provided that enables secure connections from a web browser.
X11vnc um servidor de VNC para Linux com uma apresentação bastante superior à do vncserver, pois é servidor de VNC e cliente de X11 ao mesmo tempo, permitindo que o seu cliente VNC tenha acesso à todas as facilidades do seu gerenciador de janelas
X11vnc It has built-in SSL/TLS encryption and 2048 bit RSA authentication, including VeNCrypt support; UNIX account and password login support; server-side scaling; single portHTTPS/HTTP+VNC; Zeroconf service advertising; and TightVNC and UltraVNC file-transfer
not used by x11vnc directly, but many people use SSH tunnels for VNC access.
For Unix, the traditional VNC implementation includes a "virtual" X11 server Xvnc (usually launched via the vncserver command) that is not associated with a physical display, but provides a "fake" one X11 clients (xterm, firefox, etc.) can attach to. A remote user then connects to Xvnc via the VNC client vncviewer from anywhere on the network to view and interact with the whole virtual X11 desktop.
The VNC protocol is in most cases better suited for remote connections with low bandwidth and high latency than is the X11 protocol because it involves far fewer "roundtrips" (an exception is the cached pixmap data on the viewing-end provided by X.) Also, with no state maintained the viewing-end can crash, be rebooted, or relocated and the applications and desktop continue running. Not so with X11.
SSL (TLS 1.0) will be used for server authentication and for encrypting all data transferred between the server and the client.
Negotiate The most secure layer that is supported by the client will be used. If supported, SSL (TLS 1.0) will be used. If the client does not support SSL (TLS 1.0), the RDP Security Layer will be used. This is the default setting.
RDP Security Layer Communication between the server and the client will use native RDP encryption. If you select RDP Security Layer, you cannot use Network Level Authentication.