The Ubersmith RWhois server runs on port 4321 under xinetd.
You will want to ensure that xinetd is installed on your host. On most Red Hat based distributions, this can be accomplished by running:
yum install xinetd as root.
On Debian, you can run:
apt-get install xinetd as root.
In order to enable the RWhois server, you will need to create the file
with the following content:
disable = no
type = UNLISTED
socket_type = stream
protocol = tcp
wait = no
user = ubersmith
server = /path/to/ubersmith/instance/rwhois.php
server_args = my.ubersmith.instance.com
port = 4321
Note that the server and server_args items above must be changed to accurately reflect the path to rwhois.php as well as the URL of your Ubersmith instance. Ensure that the user value represents an existing unprivileged UNIX user you are comfortable with having the RWhois service run as.
Once this file is created, restart xinetd and you will be able to query the RWhois server on port 4321 using a standard whois client.