POSTROUTING or PREROUTING
 

Server1:
-eth0 10.3.1.4
-ppp0 x.x.x.x

ServerPROXY:
-etho 10.3.1.8
-ppp0 y.y.y.y


Server1 has set FORWARD in iptables for Telnet i FTP services ( so users from LAN are able to connect those services in the internet )
ServerPROXY has Squid service (PROXY for http only)

All of the hosts in LAN must have set gaytway 10.3.1.4 (eth0 Server1)

What should I do to redirect all connection from LAN on port 80 redirect to serverPROXY 10.3.1.8:8080 ?

I heard that POSTROUTING or PREROUTING rule need to be used
Any suggestions ?

It is Prerouting.

How exactelly should it looks like ?