dual ethernet and portforwarding

I am having troube with portforwarding. I am using Redhat 9 with a
custom kernal.

I want my linux box to sit inbetween the router and switch, and to
filter all 80 request to a cache server, and forward the rest of the
rest of the ports out the Internet

Swich ---------------> Eth0 ------------- -> Eth1-------------> Router

I have the following options compiled in the kernel:

Network support
Sysctl Suport
Network Packet Filtering
TCP/IP networking
Connection Tracking
IP Tables support
Full Nat
Redirect target support
/proc filesystem support


On startup I have I a custom starting the port forward command with

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

The interfaces look like this

[root@marfa root]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:50:DA:5D:07:92
inet addr:89.11.5.204 Bcast:89.255.255.255 Mask:255.0.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2102 errors:0 dropped:0 overruns:1 frame:0
TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:224339 (219.0 Kb) TX bytes:441 (441.0 b)
Interrupt:9 Base address:0x4000

eth1 Link encap:Ethernet HWaddr 00:50:DA:C3:FB:7C
inet addr:89.11.5.205 Bcast:89.255.255.255 Mask:255.0.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2040 errors:0 dropped:0 overruns:0 frame:0
TX packets:104 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:214588 (209.5 Kb) TX bytes:10333 (10.0 Kb)
Interrupt:10 Base address:0x4080

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:700 (700.0 b) TX bytes:700 (700.0 b)


And the route table looks like this:

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
89.0.0.0 * 255.0.0.0 U 0 0
0 eth1
89.0.0.0 * 255.0.0.0 U 0 0
0 eth1
127.0.0.0 * 255.0.0.0 U 0 0
0 lo
default 89.0.0.99 0.0.0.0 UG 0 0
0 eth0


Any Ideas on why this isn't working?

Thanks in advance!!!!

-Lance

Lance Miller <lance@blackfoot.net> wrote:
> I am having troube with portforwarding. I am using Redhat 9 with a
> custom kernal.
>
> I want my linux box to sit inbetween the router and switch, and to
> filter all 80 request to a cache server, and forward the rest of the
> rest of the ports out the Internet

In that case, all you need is a simple

Swicth -- (Eth0 -- PROXY -- Eth1) -- Router

iptables -t nat -A PREROUTING -i eth0 -p tcp \
--dport 80 -j REDIRECT --to-port 3128

You also need to tell squid that its acting as a transparent proxy. See
the Squid User Guide for more information.

http://squid-docs.sourceforge.net/la...tml/c2519.html

--
Cameron Kerr
cameron.kerr@paradise.net.nz : http://nzgeeks.org/cameron/
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