By default Clerezza listens to port 8080 for http requests and to port 8022 for ssh connections. As Clerezza is typically run as an unpriviledged user (user reto in the example above) it cannot listen to default ports like port 80 for the web.
One way to redirect the default web port 80 to port 8080 is to use xinetd. This is not installed by default.
Install xinetd with
sudo apt-get install xinetd
For redirecting the http port 80 to 8080 you can place a file with following content into the directory /etc/xinet.d.
disable = no
flags = REUSE
socket_type = stream
protocol = tcp
user = root
wait = no
port = 80
redirect = 127.0.0.1 8080
log_type = FILE /tmp/xinetdssl.log
Finally tell xinetd to reload the config with:
sudo /etc/init.d/xinetd reload
Alternatives to xinetd include inet.d and iptables