rsync problem

Hi folks,
I've installed fou4s on all machines in my network and updating SuSE 
8.1 seems to work  fine. Now, I'd like to update KDE, too.

As far as I understood the rsync-protocol is used for that purpose. 
I've uncommented the KDE-server line in the config file, but a 
"saturn:~ # fou4s -uv" leads to:
________________________________________________________
Generating patch descriptions from rsync://ftp.gwdg.de/pub/linux/	
suse/ftp.suse.com/suse/i386/supplementary/KDE/update_for_8.1/
update_for_8.1/
rsync: getaddrinfo: ftp.gwdg.de 873: Temporary failure in name 
resolution
rsync error: error in socket IO (code 10) at clientserver.c(97)
Could not find gpd.
________________________________________________________

I'm not used to the rsync-protocol, I've never used it before as 
people claim it to be very insecure.
[1] Workstations are behind a firewall. Do I need to open ports for 
rsync to work?
[2] Do I need to set-up and run rsyncd?

Also, I've mirrored a suse ftp-server (including KDE -packages) and 
updated machines by hand/script. I'd like to keep that mirror, but: 
how to set-up fou4s to use that (local) mirror only for base system 
and KDE updates? Is it possible for the workstations to use 
NFS-shares from that mirror instead of external servers via ftp/
rsync?

thanks in advance,
Michael

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