When running node.js apps, you will typically bind your apps to another port such as 8080. However, you may not want to require users to specify a port in the endpoint,

To redirect port 80 to port 8080, first open the iptables configuration file

$ vi /etc/sysconfig/iptables

You'll want to make sure that the port for your app and port 80 are both open.

-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 8080 -j ACCEPT

Then, at the bottom of the file you'll want to setup some prerouting under network address translation.

*nat
-A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080
COMMIT  

Assuming you're doing this to a previously untouched iptables configuration file, it should look something like this when you're done:

*filter
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 8080 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT  
*nat
-A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080
COMMIT  

When you're done, save the file and restart iptables

$ service iptables restart

Now you can view localhost:8080 on localhost