VNC简介

VNC(Vitual Network Computing) is a graphical desktop sharing system that uses the RFB protocol to remotely control another computer. It transmits the keyboard and mouse events from on computer to another, relaying the graphical screen updates back in the other direction, over a network.

VNC is platform-independent --- a VNC viewer on one operating system may connect to a VNC server on the same or any other operating system. There are clients and servers for many GUI-based operating system and for Java. Multiple clients may connect to a VNC server at the same time. Popular uses for this technology include remote technical support and accessing files on one's work computer from one's home computer, or vice versa.

A VNC system consists of a client, a server, and a communication protocol:

• The VNC server is the program on the machine that shares its screen. The server passively allows the client to take control of it.
• The VNC client(or viewer) is the program that watches, controls, and interacts with the server. The client controls the server.
• The VNC protocol(RFB) is very simple, based on one graphic primitive from server to client("Put a rectangle of pixel data at the specified X,Y position") and event messages from client to server.

By default, RFB is not a secure protocol. While passwords are not sent in plain-text(as in telnet), cracking could prove successful if both the encryption key and encoded password are sniffed from a network. For this reason it is recommended that a password of at least 8 characters be used.

由于VNC系统是服务器-客户端模式的，所以先得在服务器(被控制的一方)上装上VNCserver,然后在客户端(主动控制的一方)上装上client(VNCviewer)。按照vncserver --help说明启动vncserver。服务器端有三个命令可以使用：vncconfig---配置命令，vncpasswd---设置client连接到服务器时需要的密码，vncserver启动一个server进程(对应一个Display No.)，监听端口。

在服务器端的/root目录下会有个隐藏的文件夹.vnc，里面有加密过的密码文件passwd，每个vncserver进程的日志文件，以及配置文件xstartup。

服务器端启动vncserver后，即可在客户端启动vncviewer，在server一项中输入服务器的ip,后面跟一个:，以及一个Display No.,如果服务器端只启动了一个vncserver进程，那么就是1。然后直接回车，出现需要输入密码的登录框，输入服务器端设置的密码，然后直接回车即可。