first off this is what my firewall script looks like 

#!/bin/bash
IPTABLES='/sbin/iptables'
#
EXTIF='ppp0'
INTIF1='eth0'
INTIF2='eth1'
#
EXTERNEL_NETWORK="69.159.33.78"
INTERNAL_NETWORK1="192.168.2.0/24"
INTERNAL_NETWORK2="10.0.0.0/24"
#
ROUTER_IP="10.0.0.1"
PROXY_SERVER="10.0.0.1"
PROXY_PORT="3128"
#
/bin/echo 1 > /proc/sys/net/ipv4/ip_forward
#
$IPTABLES -F
$IPTABLES -X
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
$IPTABLES -t nat -A POSTROUTING -o $INTIF1 -j MASQUERADE
$IPTABLES -t nat -A POSTROUTING -o $INTIF2 -j MASQUERADE
$IPTABLES -A FORWARD -i $INTIF1 -o $EXTIF -m state --state NEW,ESTABLISHED -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF2 -o $EXTIF -m state --state NEW,ESTABLISHED -j ACCEPT
#
$IPTABLES -A INPUT --protocol tcp --dport 20 -j ACCEPT
$IPTABLES -A INPUT --protocol tcp --dport 21 -j ACCEPT
$IPTABLES -A INPUT --protocol tcp --dport 22 -j ACCEPT
$IPTABLES -A INPUT --protocol tcp --dport 23 -j ACCEPT
$IPTABLES -A INPUT --protocol tcp --dport 80 -j ACCEPT
$IPTABLES -A INPUT --protocol tcp --dport 443 -j ACCEPT
#
$IPTABLES -A INPUT  -i $EXTIF -s $EXTERNEL_NETWORK  -d $EXTERNEL_NETWORK  --protocol tcp --dport 3128 -j DROP
$IPTABLES -A INPUT  -i $EXTIF -s $EXTERNEL_NETWORK  -d $EXTERNEL_NETWORK  --protocol tcp --dport 10000 -j DROP
$IPTABLES -A INPUT  -i $EXTIF -s $EXTERNEL_NETWORK  -d $EXTERNEL_NETWORK  --protocol tcp --dport 1337 -j DROP
$IPTABLES -A INPUT  -i $EXTIF -s $EXTERNEL_NETWORK  -d $EXTERNEL_NETWORK  --protocol tcp --dport 53 -j DROP
$IPTABLES -A INPUT  -i $EXTIF -s $EXTERNEL_NETWORK  -d $EXTERNEL_NETWORK  --protocol tcp --dport 67 -j DROP

#
$IPTABLES -A INPUT  -i $INTIF1 -s $INTERNAL_NETWORK1 -d $INTERNAL_NETWORK1 --protocol udp --dport 67 -j REJECT
$IPTABLES -A INPUT  -i $INTIF2 -s $INTERNAL_NETWORK2 -d $INTERNAL_NETWORK2 --protocol udp --dport 67 -j ACCEPT
#
$IPTABLES -A INPUT  -i $INTIF1 -s $INTERNAL_NETWORK1 -d $INTERNAL_NETWORK1 --protocol tcp --dport 3128 -j ACCEPT
$IPTABLES -A INPUT  -i $INTIF2 -s $INTERNAL_NETWORK2 -d $INTERNAL_NETWORK2 --protocol tcp --dport 3128 -j ACCEPT

#
$IPTABLES -A INPUT  -i $INTIF2 -s $INTERNAL_NETWORK2 -d $INTERNAL_NETWORK2 --protocol tcp --dport 53 -j ACCEPT
$IPTABLES -A INPUT  -i $INTIF2 -s $INTERNAL_NETWORK2 -d $INTERNAL_NETWORK2 --protocol udp --dport 53 -j ACCEPT

#
#
$IPTABLES -t nat  -A PREROUTING -i $INTIF1 -s $INTERNAL_NETWORK1 -d $INTERNAL_NETWORK1 -p tcp --dport 80 -j ACCEPT
$IPTABLES -t nat  -A PREROUTING -i $INTIF1 -s ! $PROXY_SERVER -p tcp --dport 80 -j DNAT --to $PROXY_SERVER:$PROXY_PORT
$IPTABLES -t nat  -A POSTROUTING -o $INTIF2 -s $INTERNAL_NETWORK2 -p tcp -d $PROXY_SERVER -j SNAT --to $ROUTER_IP
$IPTABLES -t filter -I FORWARD -s $INTERNAL_NETWORK2 -d $PROXY_SERVER -i $INTIF1 -o $INTIF2 -p tcp --dport $PROXY_PORT -j ACCEPT
#
$IPTABLES -t nat  -A PREROUTING -i $INTIF2 -s $INTERNAL_NETWORK2 -d $INTERNAL_NETWORK2 -p tcp --dport 80 -j ACCEPT
$IPTABLES -t nat  -A PREROUTING -i $INTIF2 -s ! $PROXY_SERVER -p tcp --dport 80 -j DNAT --to $PROXY_SERVER:$PROXY_PORT
$IPTABLES -t nat  -A POSTROUTING -o $INTIF2 -s $INTERNAL_NETWORK2 -p tcp -d $PROXY_SERVER -j SNAT --to $ROUTER_IP
$IPTABLES -t filter -I FORWARD -s $INTERNAL_NETWORK2 -d $PROXY_SERVER -i $INTIF2 -o $INTIF2 -p tcp --dport $PROXY_PORT -j ACCEPT
#
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,INVALID -j DROP
$IPTABLES -A FORWARD -i $EXTIF -m state --state NEW,INVALID -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF2 -m state --state NEW,INVALID -j ACCEPT




now that you have seen that this is my problem 
(this machine is located on  eth1 lan )
nethic@s0cket-LPC:~$ ping google.com
connect: Network is unreachable
nethic@s0cket-LPC:~$

i'v called a ip from 10.0.0.1 via eth1 on my router . i can ssh to 10.0.0.1 and use my web via the proxy running on port 3128 and query hostnames via $host <host> 
but i can not access anything otherwise 

is there something i'm not seeing here  
i can paste more info if needed