I'm running a chumby with a USB drive in the back to make it run a single dedicated application I wrote myself. My debugchumby script starts by running /usr/chumby/scripts/sync_time.sh, and then invokes my application via chumbyflashplayer.x.

I wasn't quite sure if running that script synchronised the time once or started a daemon that would keep it permanently in sync, so I've been tcpdumping all the chumby's network traffic for a few days to see if I can prove whether it's doing any network time synchronisation at all. I haven't found any yet, even at bootup - yet the chumby reliably gets the right time when it starts up. Do I need to do something more in the debugchumby script?

Also, I recently experienced a glitch in the application which would be most easily explained by the chumby's clock having jumped backward by a second. So I wondered if the chumby might be using a time sync protocol which didn't take care to keep the clock monotonic. Some forum posts here support this, saying that chumby uses rdate rather than NTP - but my tcpdump doesn't show any instances of rdate either, so I'm confused.

How does chumby's time sync software work in general? Will it run continuously after I invoke sync_time.sh? Should I have done something specific to make it run continuously? Is there an internal backup clock of any kind? Is it expected behaviour that occasionally a Flash application can experience a small backward clock jump? (I can work around it if the answer is yes, but I want to be convinced that that's really what's happening before I do that.)