X Protocol Forwarding
The X Window System provides support for graphical display on UNIX systems. X protocol forwarding provides a way to secure the communication between X clients and remote X servers. X forwarding is enabled by default. X forwarding works as follows:
- If X forwarding is enabled, the Secure Shell client requests X forwarding when it connects to the server.
- If X forwarding is supported by the server, the server sets itself up as a proxy X server on the server host, and sets the DISPLAY environment variable in the client shell to point to the proxy X display.
- When you run an X client program on the server host, it connects to the proxy display.
- The Secure Shell client acts as a proxy X client and connects to the X server on the client host.
- All X protocol information is sent through the Secure Shell channel.