[LARTC] Port based routing with transparent proxy

[LARTC] Port based routing with transparent proxy

[Brett =?unknown-8bit?q?Cav=C3=A9?=]

Hi all,

I have a RH9.0 system configured as a gateway. I am running squid,
configured for transparent proxy.
I have 3 NIC's - 1 LAN (eth0), 1 with an ADSL (ppp0) via pppoe (eth2,
0.0.0.0) connection, and a leased line (eth1).

I have set up port based routing, using the mangle table with a MARK
target for http and https traffic. The routing works fine until I use
transparent proxy. Is there a way to route traffic coming out of squid
to use the adsl connection?

I have the following rules
iptables -t mangle -A PREROUTING -p tcp -i $LANIF --dport 80 -j MARK
--set-mark 1
iptables -t nat -A PREROUTING -p tcp -i $LANIF --dport 80 -j REDIRECT
--to-port 3128	#if this is commented out, port routing works, if not it
doesn’t.

My default route is a router connected to the leased line interface
(eth1). I have added ip rules and ip routes as documented on the lartc
website (ip rule add fwmark 1 ### etc, and ip route add ### table 201
etc)

I have tried "iptables -t mangle -A POSTROUTING -o ! $LANIF etc" but
this doesn’t work, as expected, as routing has already taken place. Any
suggestions would be appreciated.

Regards
Brett


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