How to use iptables in linux to forward http and https traffic to a transparent proxy

linux firewall iptables gateway transparentproxy
ajt picture ajt · May 23, 2012 · Viewed 62.1k times · Source

I have a Ubuntu linux system acting as a gateway system with two interfaces on it. One interface is for the local network and one interface is for the internet. I am able to route traffic through it with no problem at all. I use two iptables rules to forward outbound traffic from the internal interface:

iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE
iptables --append FORWARD --in-interface eth1 -j ACCEPT

I now need to create an iptables rule that filters out and redirects all tcp port 80 and 443 traffic leaving my network through the eth1 interface and send it to a proxy server that resides on a loopback interface on tcp port 9090.

I have been searching all over SO but I have not been able to find an example that works. Is there an efficient way to do this?

Answer

Diego Woitasen picture Diego Woitasen · May 23, 2012 
iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 9090

HTTPS cannot be used with a transparent proxy. There are some hacks, but it doesn't make any sense and is useless.

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