How to forward connection from one interface to another under linux

Is this box routing the traffic between those interfaces? From what you wrote I assume that on eth0 there is a public network connected to the Internet, while there is a private local network on eth1.

If thats the setup and you want to access webserver on local network from the Internet you have to use Network Address Translation (NAT).

Basicly you need to figure an external IP address on the "outside" interface and add iptables rule:

iptables -t nat -A PREROUTING -p tcp -d X.X.X.X --dport 8080 -j DNAT --to Y.Y.Y.Y:8080

X.X.X.X is the external address while Y.Y.Y.Y is the internal one running webserver. In that scenario you also have to make sure you are allowing the traffic in the forward chain:

iptables -A FORWARD -p tcp -d Y.Y.Y.Y --dport 8080 -j ACCEPT

Your box has to have forwarding enabled for this:

sysctl net.ipv4.ip_forward=1 

or

echo 1 > /proc/sys/net/ipv4/ip_forward

Not sure if thats answer your question, but gave very little details in you question.