[CentOS] redirecting web requests from localhost

Thu Aug 29 11:37:05 UTC 2013
Gary Hodder <vk2kcf at vk2kcf.com>

On Wed, 2013-08-28 at 21:49 +0200, Miguel González wrote:
> Dear all,
>     I´m testing a server and try to simulate a server in production. We 
> have a SSL certificate and I have configured the test server with the 
> same servername as it is in production. To access it, I change the hosts 
> file in my laptop to reach the test server.
>     However, the Java application running in the server tries to access 
> some local web content. I have changed the hosts file and some 
> applications (ping, wget) they get the local IP address. However 
> nslookup and maybe our Java application (I didn´t have the programmer 
> available to debug it) are getting the production server IP.
>     So, how can I redirect for instance 443 traffic to a specific IP to 
> the local IP address of the local server? I have tried this:
>      iptables -t nat -A PREROUTING -d XXX.XXX.XXX.XXX -p tcp --dport 80 
>    XXX.XXX.XXX.XXX - IP of production server
>    YYY.YYY.YYY.YYY - local IP of the test server
>    Thanks
>    Miguel

You have the prerouting but you have to forward it as well.
This allows a connection on the Internet to make a connection to a
internal machine on my local network.
Router machine's local network ip on eth1. internal machine. 

iptables -A FORWARD -p tcp -i ppp0 -o eth1 -d --dport 1234 -j
iptables -t nat -A PREROUTING -p tcp -i ppp0 --dport 1234 -j DNAT

ip and ports changed to protect the guilty :)