"error in rsync protocol data stream (code 12) at io.c(150)" revisited

[Herta Van den Eynde]

I browsed the web and the archive, and apart from someone asking whether 
anyone else had rsync problems after installing OpenSSH 3.4, I came up 
empty.
Can anyone point me in the right direction to debug this?  I've got over 
50 GB to keep in sync, and don't know of another elegant way to do it.

Environment:
source system = bb:
- Linux version 2.4.7-10smp (bhcompile at stripples.devel.redhat.com) (gcc 
version 2.96 20000731 (Red Hat Linux 7.1 2.96-98))
- OpenSSH_3.4p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
- rsync  version 2.5.5  protocol version 26
target system = tobias:
- Linux version 2.4.17 (root at www-100) (gcc version 2.95.4 (Debian 
prerelease))
- OpenSSH_3.4p1 Debian 1:3.4p1-1, SSH protocols 1.5/2.0, OpenSSL 0x00906
- rsync version 2.5.6cvs  protocol version 2603f
Neither system uses an rsync daemon.

Here's the command and the resulting error:

bb> ls -l ccf.txt
-rw-r--r--    1 bbuser   bbuser         46 Jul  2 12:02 ccf.txt
bb> echo $RSYNC_SSH
/usr/local/bin/rsync -i /home/bbuser/.ssh/bbcom-id-dsa
bb> rsync -a ccf.txt bbcom at tobias:/www2/virtualhosts/toledo/bbcom/
tobias.cc.kuleuven.ac.be: Connection refused
unexpected EOF in read_timeout

ssh by itself works as expected:

bb>  ssh -i ~/.ssh/bbcom-id-dsa -l bbcom tobias cat 
/www2/virtualhosts/toledo/bbcom/t.txt
Hello from tobias
bb>  ssh -i ~/.ssh/bbcom-id-dsa -l bbcom tobias date
Tue Oct  1 15:49:21 CEST 2002

And scp proves I can write in the target directory as well:

bb> scp -i  ~/.ssh/bbcom-id-dsa ccf.txt 
bbcom at tobias:/www2/virtualhosts/toledo/bbcom/
ccf.txt              100% |*****************************|    46       00:00

Any help greatly appreciated.

Herta Van den Eynde