http://www.phuketadmin.org/index.php?topic=7222.0
Squid is a very well known and vastly used cache proxy server for the common web protocols such as HTTP, HTTPS, FTP and more. It caches frequently accessed web pages and thus reduces bandwidth and response time. Squid is available for almost all the platforms including Windows. It is open source and available under GNU/GPL.
Advantages of setting up Squid as Transparent Proxy include the fact that you don't need to configure all the machines on your LAN to connect to Squid manually. All the traffic would be redirected to the Squid Listening Port automatically and your Ubuntu Box would act like a Router.
Follow these steps to set up a Transparent Proxy Server with Squid3 on Ubuntu 11.10 (Oneiric Ocelot)
1. Install Ubuntu Oneiric Ocelot Server or Desktop on your computer.
2. Change your network interfaces from DHCP to Static
nano /etc/network/interfaces
Delete all the text and paste this text in your interfaces file:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.0.12
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.0.3
auto eth1
iface eth1 inet static
address 192.168.2.1
netmask 255.255.255.0
network 192.168.2.0
broadcast 192.168.2.255
Where 192.168.0.12 is the IP address of your WAN interface and 192.168.2.1 is the IP address of your LAN interface.
nano /etc/resolv.conf
Paste this text in the file that opens up:
nameserver 127.0.0.1
when one sees "127.0.0.1" in the list of DNS servers it
suggests that one is running a local, caching-only name server.
3. Install squid3:
sudo apt-get install squid3
4. Make a backup of your squid.conf for future reference. Squid.conf has nearly all the options listed and it is recommended to go through that file to know more about squid options.
cp /etc/squid3/squid.conf /etc/squid3/squid.conf.original
Configure squid3.
nano /etc/squid3/squid.conf
Remove all the text and paste this text in your squid.conf file:
http_port 3128 transparent
acl LAN src 192.168.2.0/24
acl localnet src 127.0.0.1/255.255.255.255
# Limited file download < 250 MB
reply_body_max_size 250 MB
http_access allow LAN
http_access allow localnet
# No cache anything
no_cache deny all
Where 192.168.2.0/24 is the range of your LAN interface. The last line in that file is defining a cache directory for squid3 to use. Here, the first number denotes the size of cache in MB, 20 GB in this case.
Save and close this file.
6. Restart squid3:
/etc/init.d/squid3 restart
7. Edit /etc/sysctl.conf:
nano /etc/sysctl.conf
In this file, uncomment the lines that enable packet forwarding for IPv4 and IPv6:
net.ipv4.ip_forward=1
Save and close this file.
8. Define IPTABLE rules for port forwarding.
nano /etc/fw.proxy
Paste this text in the file that opens up:
#!/bin/sh
# squid server IP
SQUID_SERVER="192.168.2.1"
# Interface connected to Internet
INTERNET="eth0"
# Interface connected to LAN
LAN_IN="eth1"
# Squid port
SQUID_PORT="3128"
# 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
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
# 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
iptables -I INPUT -p tcp -m tcp --dport 53 --syn -j ACCEPT
iptables -I INPUT -p tcp -m tcp --dport 82 --syn -j ACCEPT
# Algo string
iptables -I FORWARD -m string --algo bm --string "BitTorrent" -j DROP
iptables -I FORWARD -m string --algo bm --string "BitTorrent protocol" -j DROP
iptables -I FORWARD -m string --algo bm --string "peer_id=" -j DROP
iptables -I FORWARD -m string --algo bm --string ".torrent" -j DROP
iptables -I FORWARD -m string --algo bm --string "announce.php?passkey=" -j DROP
iptables -I FORWARD -m string --algo bm --string "torrent" -j DROP
iptables -I FORWARD -m string --algo bm --string "announce" -j DROP
iptables -I FORWARD -m string --algo bm --string "tracker." -j DROP
iptables -I FORWARD -m string --algo bm --string "info_hash" -j DROP
iptables -I FORWARD -m string --algo bm --string "/default.ida?" -j DROP #codered virus
iptables -I FORWARD -m string --algo bm --string ".exe?/c+dir" -j DROP #nimda virus
iptables -I FORWARD -m string --algo bm --string ".exe?/c_tftp" -j DROP #nimda virus
# bittorrent key
iptables -I FORWARD -m string --string "peer_id" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "BitTorrent" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "BitTorrent protocol" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "bittorrent-announce" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "announce.php?passkey=" --algo kmp --to 65535 -j DROP
# DHT keyword
iptables -I FORWARD -m string --string "info_hash" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "get_peers" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "announce" --algo kmp --to 65535 -j DROP
iptables -I FORWARD -m string --string "announce_peers" --algo kmp --to 65535 -j DROP
iptables -I INPUT -s 0.0.0.0/0 -m string --string "info_hash" --algo bm -j DROP
iptables -I INPUT -s 0.0.0.0/0 -m string --string "announce" --algo bm -j DROP
iptables -I INPUT -s 0.0.0.0/0 -m string --string "torrent" --algo bm -j DROP
iptables -I INPUT -s 0.0.0.0/0 -m string --string "sumotracker" --algo bm -j DROP
iptables -I INPUT -p tcp -m tcp --dport 22222 --dst $SQUID_SERVER -j ACCEPT
iptables -I INPUT -p tcp -m tcp --dport 22222 --dst 192.168.0.12 -j ACCEPT
iptables -A INPUT -j LOG --log-level info --log-prefix "INPUT "
iptables -A OUTPUT -j LOG --log-level info --log-prefix "OUTPUT "
iptables -A FORWARD -j LOG --log-level info --log-prefix "FORWARD "
# DROP everything and Log it
iptables -A INPUT -j LOG
iptables -A INPUT -j DROP
Block torrent
Save and close this file.
Change Mode
chmode +x /etc/fw.proxy
9. Edit /etc/rc.local:
nano /etc/rc.local
Paste this text at the end of the file that opens up but before "exit 0":
/etc/fw.proxy
Save and close this file.
10. Reboot your server.
If you don't want to go to each machine on your Network and configure it for a Static IP, you can use dhcp3-server to assign Dynamic IPs to all the computers on your LAN and make them forward all there internet traffic to your squid box.
11. Install dhcp3-server:
apt-get install dhcp3-server
12. Edit /etc/default/dhcp3-server:
nano /etc/default/isc-dhcp-server
Type eth1 in between the quotes in this line:
INTERFACES=""
Save and close this file.
13. Make a backup of your original /etc/dhcp/dhcpd.conf:
cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.original
14. Edit /etc/dhcp/dhcpd.conf:
nano /etc/dhcp/dhcpd.conf
Delete all the text and paste this text in the file that opens up
ddns-update-style none;
log-facility local7;
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.100 192.168.2.200;
option domain-name-servers 192.168.2.1;
option routers 192.168.2.1;
option broadcast-address 192.168.2.255;
default-lease-time 600;
max-lease-time 7200;
}
We are using True (ISP in Thailand) DNS in this example. You can use your own DNS Server if you've configured one on your network.
Save and close this file.
Make sure all the cables on your network are plugged in and the devices are powered on.
15. Start dhcp3-server:
service dhcp3-server start
16. Reboot your server.
17. Install Bind9 if you didn't install it
Install dnsutils for dig command.
Edit conf file for Caching
Delete all the text and paste this text in the file that opens up:
apt-get install bind9 dnsutils
nano /etc/bind/named.conf.options
options {
directory "/var/cache/bind";
forwarders {
203.144.207.29;
203.144.207.49;
};
auth-nxdomain no;
allow-query { any; };
};