rsync howto:

   source-host   data   destination-host
   rsync daemon  |-->   rsyncs the source
                tcp 873

source-host:
===========

a) /etc/rsyncd.conf

#  file: rsyncd.conf
#
uid = root
gid = root
pid file = /var/run/rsyncd.pid

[root]
	path = /
	comment = root
	exclude = /proc /mnt

[home]
	path = /home
	exclude = /home/publicftp
# eof /etc/rsyncd.conf

b) /etc/initd.d/rsyncd

#!/bin/sh
#
# chkconfig: - 90 90
# description: rsync daemon to backup this mashine
#
# skeleton  example file to build /etc/init.d/ scripts.
# This file should be used to construct scripts for /etc/init.d.
#
# Written by Miquel van Smoorenburg <miquels@cistron.nl>.
# Modified for Debian GNU/Linux
# by Ian Murdock <imurdock@gnu.ai.mit.edu>.
#
# Version:  @(#)skeleton  1.9.1  08-Apr-2002  miquels@cistron.nl
# file: rsyncd
#

# Source function library.
. /etc/init.d/functions

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DAEMON=/usr/bin/rsync
NAME=rsync
DESC="rsync"
DAEMON=/usr/bin/rsync

test -x $DAEMON || exit 0

case "$1" in
   start)
      echo -n "Starting $DESC: $NAME"
      $DAEMON --config=/etc/rsyncd.conf --daemon -z
      touch /var/run/$NAME.pid
      echo "."
   ;;
   stop)
      echo -n "Stopping $DESC: $NAME "
      kilall rsync
      echo "."
   ;;
   restart)
      $0 stop
      sleep 1
      $0 start
   ;;
   *)
      N=/etc/init.d/$NAME
      echo "Usage: $N {start|stop|restart}" >&2
      exit 1
   ;;
esac
   
exit 0
# eof /etc/initd.d/rsyncd

c) optional: add a firewall rule

IPofDestHost="1.2.3.4"
iptables -A INPUT -i $INET_IFACE -s ${IPofDestHost} -p tcp --dport 873 -j ACCEPT

destinaton-host:
===============

a) executes rsync

#!/bin/sh
#
# file:	rsyncScript.sh
#
IPofSourceHost="1.2.3.4"
/usr/bin/rsync -az --delete-after --ignore-errors ${IPofSourceHost}::root /targetDirectory/
# eof rsyncScript.sh

b) add to roots cron tab

# backs up source mashine every night 2 o'clock
0 2 * * * nohup /PathOfScript/rsyncScript.sh >/dev/null 2>&1 &

# eof