how to configure transparent squid proxy server in centos 6.4

1 step 

squid installation
open terminal and type following command

#yum install squid  -y

2 step

now edit and change  main configuration file

#nano /etc/squid/squid.conf

# TRANSPARENT SQUID ON CENTOS 6.4

# Recommended minimum configuration:

#

acl manager proto cache_object

acl localhost src 127.0.0.1/32 ::1

acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1

acl lan src 192.168.1.1/8   #******YOUR LOCAL LAN (NEW LINE)*****

# Example rule allowing access from your local networks.

# Adapt to list your (internal) IP networks from where browsing

# should be allowed

acl localnet src 10.0.0.0/8 # RFC1918 possible internal network

acl localnet src 172.16.0.0/12 # RFC1918 possible internal network

acl localnet src 192.168.0.0/16 # RFC1918 possible internal network

acl localnet src fc00::/7 # RFC 4193 local private network range

acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines

acl SSL_ports port 443

acl Safe_ports port 80 # http

acl Safe_ports port 21 # ftp

acl Safe_ports port 443 # https

acl Safe_ports port 70 # gopher

acl Safe_ports port 210 # wais

acl Safe_ports port 1025-65535 # unregistered ports

acl Safe_ports port 280 # http-mgmt

acl Safe_ports port 488 # gss-http

acl Safe_ports port 591 # filemaker

acl Safe_ports port 777 # multiling http

acl CONNECT method CONNECT

#

# Recommended minimum Access Permission configuration:

#

# Only allow cachemgr access from localhost

http_access allow manager localhost

http_access deny manager

# Deny requests to certain unsafe ports

http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports

http_access deny CONNECT !SSL_ports

# We strongly recommend the following be uncommented to protect innocent

# web applications running on the proxy server who think the only

# one who can access services on "localhost" is a local user

#http_access deny to_localhost

# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS

#

# Example rule allowing access from your local networks.

# Adapt localnet in the ACL section to list your (internal) IP networks

# from where browsing should be allowed

http_access allow localnet

http_access allow localhost

# And finally deny all other access to this proxy

http_access deny all

http_access allow lan  ############(ADD NEW LINE)#########

# Squid normally listens to port 3128

http_port 3128 transparent

# We recommend you to use at least the following line.

hierarchy_stoplist cgi-bin ?

# Uncomment and adjust the following to add a disk cache directory.

#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir

coredump_dir /var/spool/squid

# Add any of your own refresh_pattern entries above these.

refresh_pattern ^ftp: 1440 20% 10080

refresh_pattern ^gopher: 1440 0% 1440

refresh_pattern -i (/cgi-bin/|\?) 0 0% 0f

refresh_pattern . 0 20% 4320

#visible_hostname localhost  #######ADD NEW LINE#######

step 3

 now, change firewall rule  

type command 

#iptables -I INPUT -s 192.168.8.14/8 -p tcp --dport 4480 -j ACCEPT

#iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to #192.168.8.14:4480

#iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 4480

#service iptables save

#service iptables restart

step 4

start squid service

command

#service squid restart