Okay, it may be because I am dense or maybe just not finding the right source, but I can't understand why one of these IPTABLES setups would be better than the other.
Here is my setup:
I have a box that is serving as a transparent proxy and a router or sorts. It has two interfaces on it, ETH0 and ETH1, and the following address scheme:
ETH0 = DHCP ETH1 = 192.168.5.1/24 serving up DHCP for the 192.168.5.0/24 network to clients behind it in the LAN
I have privoxy installed and listening on port 8080 as a transparent proxy. What I am accomplishing with this setup is to be able to drop this box into an existing network with minimal configuration and attached clients to the proxy.
Here is my original IPTABLES file
*nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j REDIRECT --to-port 8080 -A POSTROUTING -o eth0 -j MASQUERADE COMMIT *filter COMMIT
This configuration works fine and traffic is flowing back and forth without issue. I get the originating clients IP address in the privoxy logfiles, and life is good.
My confusion comes in when I start looking at other people's configurations and see that they are using DNAT instead of REDIRECT, and I am trying to understand the real beneift of one over the other. Here is a sample config:
*nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j DNAT --to 192.168.5.1:8080 -A POSTROUTING -o eth0 -j MASQUERADE COMMIT *filter COMMIT
Again, this configuration works too, and gives me all I need from a logging perspective...
Which is is right, or maybe MORE right, than the other one?
Thanks for taking time to read this far...