Script NAT Proxy

Contoh script NAT / Proxy

Untuk menjalankan

# ./script.sh start

Untuk mematikan

# ./script.sh stop

Agar script.sh langsung on waktu komputer di booting, anda dapat menuliskan script tersebut di folder (misalnya) /root. Masukan pada file /etc/rc/local perintah

/root/script.sh start

Isi script.sh adalah seperti tampak di bawah ini. Ada beberapa parameter yang perlu di perhatikan yaitu

• UPLINK
• NAT
• INTERFACES

Pastikan bahwa anda mengisi ketiga-nya dengan benar

isi script.sh

#!/bin/bash

# From: AHK <akuhon@kompas.com>
# To: linux-admin@linux.or.id

# Save this file and activate through # file_name start
# and de-activate through # file_name stop

# This firewall-script can be used for workstation, laptop, router
# or server that are not running network service (such as web server, ftp
# server etc)

# change the parameter UPLINK with Interface device to the Internet.
# In our case WLAN router with NIC wlan0 connected to the Internet
# and LAN connection with eth0.
# if you use dial-up modem, you might use ppp0 as your UPLINK

UPLINK="eth1"

# if you run the gateway as router and forward IP packet between eth devices
# please fill .yes., if not, please fill .no.

ROUTER="yes"

# Please change 202.150.10.45 to your static IP address of UPLINK device.
# For those who use dial-up or dynamic IP, please enter .dynamic.

# NAT="192.168.1.100"

NAT="dynamic" 

# please list all network interfaces including eth devices
# as well as dial-up interface such as ppp0

INTERFACES="lo eth0 eth1 eth2"

if [ "$1" = "start" ]
  then
  echo "Activate Firewall ..... "
  /sbin/iptables -F
  /sbin/iptables -P INPUT DROP
#  /sbin/iptables -A INPUT -p tcp -i eth0 --destination-port 25 -s ! 192.168.0.1  -j DROP
#  /sbin/iptables -A INPUT -p tcp -i eth1 --destination-port 25 -s ! 192.168.0.1  -j DROP

  /sbin/iptables -A INPUT -i ! ${UPLINK} -j ACCEPT
  /sbin/iptables -A INPUT -i ${UPLINK} -p tcp -s 0/0 --dport 25 -j ACCEPT
  /sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
  /sbin/iptables -A INPUT -p tcp -i ${UPLINK} -j REJECT --reject-with tcp-reset
  /sbin/iptables -A INPUT -p udp -i ${UPLINK} -j REJECT --reject-with icmp-port-unreachable
 
  /sbin/iptables -A FORWARD -p tcp --destination-port 25 -s ! 192.168.0.1  -j DROP

# block bad sites
# /sbin/iptables -I INPUT -s 68.178.211.34 -j DROP
# /sbin/iptables -I INPUT -d 68.178.211.34 -j DROP 
# /sbin/iptables -I INPUT -s 64.27.5.168 -j DROP
# /sbin/iptables -I INPUT -d 64.27.5.168 -j DROP

# turn off packet spoofing in all interfaces
for x in ${INTERFACES}
  do
    echo 1 > /proc/sys/net/ipv4/conf/${x}/rp_filter
  done 

if [ "$ROUTER" = "yes" ]
  then
  # Activate IP forwarding at router
    echo 1 > /proc/sys/net/ipv4/ip_forward
if [ "$NAT" = "dynamic" ]
  then
  # Dynamic IP address, activate Masquerading
    echo "Activate Masquerading (Dynamic IP) ...."
    /sbin/iptables -t nat -A POSTROUTING -o ${UPLINK} -j MASQUERADE
elif [ "$NAT" != "" ]
  then
  # Static IP address use source NAT
  echo "Activate SNAT (static IP) ...."
  /sbin/iptables -t nat -A POSTROUTING -o ${UPLINK} -j SNAT --to ${NAT}
fi 

echo "Activate Transparent Proxy .."
for x in ${INTERFACES}
  do
    iptables -t nat -A PREROUTING -s 192.168.0.0/24 -i eth0 -p tcp --dport 80 -j REDIRECT --to-ports 8080
  done 

# echo "Activate SMTP Port Forwarding .."
# /sbin/iptables -t nat -A PREROUTING -i ${UPLINK} -m multiport -p tcp \
# --dport 25 -d ${NAT} -j DNAT --to 192.168.0.254:25
# /sbin/iptables -A FORWARD -i ${UPLINK} -m multiport -p tcp -d 192.168.0.254 \
#  --dport 25 -j ACCEPT 

fi
  elif [ "$1" = "stop" ]
    then
      echo "Deactivate Firewall ..."
      /sbin/iptables -F INPUT
      /sbin/iptables -P INPUT ACCEPT
      /sbin/iptables -F FORWARD
      /sbin/iptables -P FORWARD ACCEPT
      /sbin/iptables -F OUTPUT
      /sbin/iptables -P OUTPUT ACCEPT
      # Turn off NAT or MASQUERADING
      /sbin/iptables -t nat -F POSTROUTING
fi

Pranala Menarik

• Linux Howto
• Script NAT Transparant Proxy & Squid