The rsync service is installed and running by default, but it is not configured for general use. Rsync is configured by editing the /etc/rsyncd.conf file manually to point to a suitable file system (usually on a USB stick) for up and/or downloads. It can also be used as a convenient means to keep configurations together in one place across a testbed of multiple routers. Lastly, rsync can provide 'interesting' streams of TCP mice and elephants across a wide range of files and latencies.
