IPTABLES rule to redirect users to my internal webpage

[crazy01]

Hi All,

what i'm trying to achieve is the following and I'm 99% there. This is the last little bit i need to do.

I have a Transparent proxy server and use NTOP to monitor bandwidth, i want to use IPTABLES to redirect a user to a page on my internal apache/proxy server that says "you have used too much data today"

my proxy, ntop, etc works, but I cant get that final IPTABLES rule to work.

here is my existing IPTABLES rules

#!/bin/sh
# squid server IP
SQUID_SERVER="192.168.3.254"
# Interface connected to Internet
INTERNET="eth2"
# Interface connected to LAN
LAN_IN="eth0"
# Squid port
SQUID_PORT="8080"
# DO NOT MODIFY BELOW
# Clean old firewall
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X

# Load IPTABLES modules for NAT and IP conntrack support
modprobe ip_conntrack

echo 1 > /proc/sys/net/ipv4/ip_forward
# Setting default filter policy

iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
# Unlimited access to loop back
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Allow UDP, DNS and Passive FTP
iptables -A INPUT -i $INTERNET -m state --state ESTABLISHED,RELATED -j ACCEPT
# set this system as a router for Rest of LAN
iptables --table nat --append POSTROUTING --out-interface $INTERNET -j MASQUERADE
iptables --append FORWARD --in-interface $LAN_IN -j ACCEPT
# unlimited access to LAN
iptables -A INPUT -i $LAN_IN -j ACCEPT
iptables -A OUTPUT -o $LAN_IN -j ACCEPT
# DNAT port 80 request comming from LAN systems to squid 3128 ($SQUID_PORT) aka transparent proxy
iptables -t nat -A PREROUTING -i $LAN_IN -p tcp --dport 80 -j DNAT --to $SQUID_SERVER:$SQUID_PORT
# if it is same system
iptables -t nat -A PREROUTING -i $INTERNET -p tcp --dport 80 -j REDIRECT -to-port $SQUID_PORT
# DROP everything and Log it
iptables -A INPUT -j LOG
iptables -A INPUT -j DROP

my setup is as follows

ISP Modem == Linksys Router == (eth2)Proxyserver (eth1) ==LAN

what would the IPTABLES rule be to redirect all traffic from 192.168.3.200(a user PC) to 192.168.3.254 (Proxy/web server) on port 80.

this way the user will be displayed with a message that says they have been blocked.


I have tried a few things but none of them seemed to work for me.

Thanks for your help

[kapsikum]

may be this helps.
iptables -t nat -A PREROUTING -s 192.168.3.200 -i eth1 -j DNAT --to-destination 192.168.3.254

[cong06]

This isn't an answer, so it's most likely useless.

However, maybe what you want is to simply send everything to squid:
s_port="3128"
lan="eth0"
iptables -t nat -A PREROUTING -i $lan -p tcp --dport 80 -j REDIRECT --to-port $s_port

and then have squid take care of all your content filtering?
Squid has other features too, and maybe you want to take advantage of them:
password authentication
caching
specialized url rewriting, etc.