[K12OSN] Redirecting sound using esd (fun stuff)

John Lucas mrjohnlucas at gmail.com
Thu May 22 18:37:34 UTC 2008

Robert Arkiletian wrote:
> Just thought I would share a cool learning experience with the list.
> Today one of my students played a youtube video (with sound) on his
> client computer which did NOT have speakers. He did it by redirecting
> the sound esd stream to another client computer which did have
> speakers. Here's how he did it.
> $esdmon -s source_hostname  | esdcat > esdrec -s dest_hostname
> Of course, it works for more than just youtube. You can also redirect
> things like ogg123 -d esd song.ogg
> You can even eavesdrop on other students by redirecting (copying in
> this case) their sound stream to yourself. Pretty sneaky.
> BTW I'm still using k12ltsp 4EL (ltsp 4.1) Does this hack work on ltsp 4.2 or 5?

It can be made to work in 4.2, but you may also be aware that this 
"feature" is ripe for abuse; students randomly redirecting sound all 
through the lab, disrupting legitimate activities etc. A very noisy DOS 

         "History doesn't repeat itself; at best it rhymes."
                         - Mark Twain

| John Lucas                MrJohnLucas at gmail.com               |
| St. Thomas, VI 00802      http://mrjohnlucas.googlepages.com/ |
| 18.3°N, 65°W              AST (UTC-4)                         |

More information about the K12OSN mailing list