how to connect to rsyncd via forwarded ssh port?

[Matthias Meyer]

I've running a rsyncd and ssh port forwarding (-R 12345:localhost:873 backup at server)
on a client because the client should not reachable but over ssh.
The rsyncd should acessible because I can backup and restore files with backuppc
(a wonderfull program which use perl::rsync)
And I can "ssh -p 12345 backup at localhost" to this client too.

If I try to connect (from the machine/user where backuppc can connect) to a share
of the clients rsyncd I get different errors:

rsync -e "ssh -C -l backup -p 10021" -av /srv/Service/Installs/autosshpatch.bin backup at localhost:/BACKUP
Seems to work. But it did not connect to the share BACKUP but copy
the autosshpatch.bin in a file called BACKUP

rsync -avvv /srv/Service/Installs/autosshpatch.bin backup at localhost:12345/BACKUP
opening connection using: ssh -l backup localhost rsync --server -vvvlogDtpre.iL . 12345/BACKUP
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
f2:15:96:05:56:6b:e5:9b:93:62:c9:09:fb:57:aa:87.
Please contact your system administrator.
Add correct host key in /var/lib/backuppc/.ssh/known_hosts to get rid of this message.
Offending key in /var/lib/backuppc/.ssh/known_hosts:16
RSA host key for localhost has changed and you have requested strict checking.
Host key verification failed.
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: unexplained error (code 255) at io.c(635) [sender=3.0.3]
_exit_cleanup(code=12, file=io.c, line=635): about to call exit(255)

rsync -avvv /srv/Service/Installs/autosshpatch.bin rsync://backup@localhost:12345/BACKUP
opening tcp connection to localhost port 12345
rsync: server sent "SSH-2.0-OpenSSH_5.1" rather than greeting
rsync error: error starting client-server protocol (code 5) at main.c(1522) [sender=3.0.3]
_exit_cleanup(code=5, file=main.c, line=1522): about to call exit(5)

How I have to cnnect to a rsyncd share via local forwarded ssh port?
-- 
Don't Panic