rsync - Apr 2011 - Connection to rsyncd over ssh tunnel seems to choke up (v2.6.9 Ubuntu)

I have been running the following (from a cron script with a non password
authorized_key exchange) ...

rsync -aP -vv --exclude=".*/" -e 'ssh -fN user at site.com.au -L
8873:127.0.0.1:873' rsync://localhost:8873/data/ /data/

... and not getting much to happen as either evidenced in
/var/log/rsyncd.log or as artefacts on the local file system.

Then I started to execute the command(s) in a shell window and finally got
some action by

  (1) leaving a previous ssh tunnel process (from a "failed" attempt)
running and
  (2) then simply punching out the rsync command less the -e part?!?

It seems (to my untrained eye) that there is a race condition between
setting up the ssh tunnel and rsync client trying to tap rsyncd on tcp/873.

Is this a credible possibility or alternatively have I missed something
fundamental from the rsync command?

Cheers, Frank.

On Tue, Apr 26, 2011 at 7:00 AM, Frank Hamersley <terabite at bigpond.com>
wrote:
> rsync -aP -vv --exclude=".*/" -e 'ssh -fN user at site.com.au
-L
> 8873:127.0.0.1:873' rsync://localhost:8873/data/ /data/
The combination of daemon syntax and a remote shell tells rsync to
connect to use the remote-shell command to run a single-use daemon,
which it talks to over stdin/stdout.  No ports are applicable in such
a scenario, so no forwarding is needed.  The -N option stops the
command args from doing anything useful, so the local rsync isn't able
to talk to the remote rsync on stdin/stdout (it just hangs waiting for
some remote data).

If you want to use a single-use daemon, put a rsyncd.conf file into
the remote user's home directory and just combine -e ssh with
rsync://user at site.com.au/data/.  If you want to connect to an existing
remote daemon service, you'll need to run the port-forwarding ssh
command separately and kill it when rsync finishes (or leave it
running, and add some start-it-up-if-it-isn't-running code).

..wayne..