#!/bin/sh
#SCRIPT FOR THE SQUID PROXY
#BY FELIPE FERREIRA 12/2008
#SHOULD CONSIDER OTHER THINGS LIKE SMTP,POP3,VNC,RDP,DAMEWARE, LET THOSE PASS DIRECTLY (NO PROXING)
#PROXY CACHE, WEB ON PORT 80,443
# squid server IP
SQUID_SERVER="10.10.10.156"
# Interface connected to Internet
INTERNET="eth0"

# Interface connected to LAN
LAN_IN="eth1"

# Squid port
SQUID_PORT="9090"


# 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
modprobe ip_conntrack_ftp

# For win xp ftp client
#modprobe ip_nat_ftp
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
#LOG and ALLOW SSH to the server in port 10.10.10.156 only
iptables -A INPUT -i $INTERNET -p tcp --dport 22 -j LOG --log-prefix “SSH LOGIN: ”
iptables -A INPUT -i $INTERNET -p tcp --dport 22 -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 ($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

# DNAT port 443 request comming from LAN systems to squid ($SQUID_PORT) aka transparent proxy
iptables -t nat -A PREROUTING -i $LAN_IN -p tcp --dport 443 -j DNAT --to $SQUID_SERVER:$SQUID_PORT
# Redirect traffic back
iptables -t nat -A PREROUTING -i $INTERNET -p tcp --dport 443 -j REDIRECT --to-port $SQUID_PORT


# DROP everything and Log it
iptables -A INPUT -j LOG --log-prefix “Drop Packets: ”
iptables -A INPUT -j DROP