X11 tunnelling with audio

By default, X11 tunneling only support video but not audio. However, if both the server and the client is running Linux/Ubuntu, there is a way to do so. Hereby, I define 'server' as the machine running the actual program, 'client' as the machine which displays in front of the user.

The procedures are as follows:

1. Install and run paprefs, goto "Network server", check "Enable network access to local sound devices" and "Allow other machines on LAN to discover local sound devices"

2. on the client, run "start-pulseaudio-x11"

3. on the client, ssh to server with reverse SSH, "ssh -X -R 9998:localhost:4713 username@server"

4. in SSH, run the program on server, "PULSE_SERVER=localhost:9998 rhythmbox"