Transparent Proxy Configuration

Easy and step by step guide to install and configure a transparent squid proxy server on a linux machine[/color]

Start with the transparent proxy server configurations:

First of all download the latest squid package .
Rpm Package : Download Rpm Package For Squid

or

TarBall : Download Squid Tarball

Installation For Rpm Package :

* Go to the directory where rpm package is and issue the following command :

#rpm -ivh squid-x.x.x

Installation for Tarball Package :

* Go to directory where tarball is and issue the following commands :

#tar -zxvf squid-x.x.x.tar.gz

#cd squid-x.x.x.

# ./configure#make check

#make && make install

Now the squid is installed and we need to modify some parameters to make the proxy transparent.
The main configuration file for squid is located at /etc/squid/squid.conf#vi /etc/squid/squid.conf
make sure the following parameters are not commented.
httpd_accel_host virtual

httpd_accel_port 80

httpd_accel_with_proxy on

httpd_accel_uses_host_header on

Now you need to configure Iptables i.e. Firewall for Transparent

iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 \

-j REDIRECT --to-port 3128

iptables -A INPUT -j ACCEPT -m state \

--state NEW,ESTABLISHED,RELATED -i eth1 -p tcp \ --dport 3128

iptables -A OUTPUT -j ACCEPT -m state \

--state NEW,ESTABLISHED,RELATED -o eth0 -p tcp \ --dport 80

iptables -A INPUT -j ACCEPT -m state \

--state ESTABLISHED,RELATED -i eth0 -p tcp \ --sport 80

iptables -A OUTPUT -j ACCEPT -m state \

--state ESTABLISHED,RELATED -o eth1 -p tcp \ --sport 80