On Linux, the issue is that if you want a process to listen to a lower port (<1024), then it needs to be run as root.
You can circumvent this by running on http as a high port and redirect this high port to port 80.
Example in config file : Listen 8080
And then to redirect port 8080 to 80 via IPTABLES :
iptables -A INPUT -i eth0 -p tcp –dport 80 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp –dport 8080 -j ACCEPT
iptables -A PREROUTING -t nat -i eth0 -p tcp –dport 80 -j REDIRECT –to-port 8080