{For that, I'm greatful to My Linux Teacher (Mr. Parvin) bcz 1st time he introduce me to SQUID configurations n now I use some/lots of implementation on that configuration for that post} 

My Setup:

Server Configuration

• Step #1 : Squid configuration so that it will act as a transparent proxy
• Step #2 : Iptables configuration
• a) Configure system as router
• b) Forward all http requests to 3128 (DNAT)
• Step #3: Run scripts and start squid service

# vi /etc/squid/squid.conf

httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
acl lan src 192.168.1.1 192.168.2.0/24
http_access allow localhost
http_access allow lan 

• httpd_accel_host virtual: Squid as an httpd accelerator
• httpd_accel_port 80: 80 is port you want to act as a proxy
• httpd_accel_with_proxy on: Squid act as both a local httpd accelerator and as a proxy.
• httpd_accel_uses_host_header on: Header is turned on which is the hostname from the URL.
• acl lan src 192.168.1.1 192.168.2.0/24: Access control list, only allow LAN computers to use squid
• http_access allow localhost: Squid access to LAN and localhost ACL only
• http_access allow lan: -- same as above --

# grep -v "^#" /etc/squid/squid.conf | sed -e '/^$/d'

# cat /etc/squid/squid.conf | sed '/ *#/d; /^ *$/d'

hierarchy_stoplist cgi-bin ?
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY
hosts_file /etc/hosts
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern . 0 20% 4320
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl purge method PURGE
acl CONNECT method CONNECT
cache_mem 1024 MB
http_access allow manager localhost
http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
acl lan src 192.168.1.1 192.168.2.0/24
http_access allow localhost
http_access allow lan
http_access deny all
http_reply_access allow all
icp_access allow all
visible_hostname myclient.hostname.com
httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
coredump_dir /var/spool/squid

Iptables configuration

iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to 192.168.1.1:3128
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128

#!/bin/sh
# squid server IP
SQUID_SERVER="192.168.1.1"
# 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
# DROP everything and Log it
iptables -A INPUT -j LOG
iptables -A INPUT -j DROP

# chmod +x /etc/fw.proxy
# /etc/fw.proxy
# service iptables save
# chkconfig iptables on

# /etc/init.d/squid restart
# chkconfig squid on

Desktop / Client computer configuration

How do I test my squid proxy is working correctly?

# tail -f /var/log/squid/access.log

Problems and solutions

(a) Windows XP FTP Client

# modprobe ip_nat_ftp

(b) Port 443 redirection

(c) Squid Proxy authentication in a transparent mode

Steps

Browse by IP

1. Go to START - Run. Enter cmd and hit enter, or click on START - Program Files - Accessories - Command Prompt to open the Command Prompt window.
2. If your school has disabled access to the command prompt, right click, go to New, and select Text Document. In the text document simply type cmd then save the file as command.bat or, if this doesn't work, command.comMake sure you switch the Save As Type field in Notepad's Save dialogueto All Files. Double Click and you have successfully gained access tothe command prompt.
3. If that doesn't work, perform the following steps at home and bring the IP address to school.
4. Once in the Command Prompt, enter ping x, replacing the x with any website of your choice. 

1. You will see a set of four numbers [here, 72.14.207.99] is Google's IP address.
2. Open your browser window. In the address bar, type http://x.x.x.x, replacing the x's with the ping address, and hit enter [for example, http://72.14.207.99]. This will give you access to Google.
3. If the web filterblocked even the IP address of the site, you can take each number inthe IP and convert it to a Hexadecimal format. Then in the browser enter http:// 0x(hex1).0x(hex2).0x(hex3).0x(hex4).
4. Note: This method is very easy to trace!

Create Your Own Circumventor (similar to a proxy)

Create a redirect domain

1. Create an account at Dot.tkand create a ".tk" domain for that site. This works great for tworeasons. First of all, many firewalls use keyword blocking. Forexample, if the domain for a website contains the word "sex," it may beblocked regardless of what the page is actually about. Therefore, allyou need to do is give your .tk version a different name. It also worksbecause .tk is not an actual domain, rather a redirect to a domain, andprobably won't be blocked.

Browse by Proxy

• Since proxies get blocked often you should join a proxy mailing list like the one below to keep getting fresh proxies daily.
  tech.groups.yahoo.com/group/fresh-proxy/join (copy/paste this in your browser)

• http:// letmego.info

• http://planetmuffin.com

• http:// www.proxyauthority.com to stay up to date on the newest proxies
• http:// proxy.techiebraindump.com
• http:// www.helpmesurf.net

• http:// www.surfingstore.info/
• http:// freebrowse.info/
• http:// surfingtoday.info/
• http:// findwealth.info/
• http:// proxy.acevpn.com/

1. Try using (remove spaces) badfox . co.cc, It just came out I will update this when new ones come
2. Find a proxy site. Do a search for "free online proxies". This will provide you with a list of proxies to bypass filters.
3. Find a proxy site that is obviously, not blocked by the filters.
4. Type the name of the site you want to access into the box. Most sites have a checkbox that says "block scripts"; it is better to uncheck this.
5. Ifnone of these work, download and install Firefox and manually changethe proxy settings by going to Tools - Options - ConnectionSettings - And change the Proxy Settings to a proxy. Go to ask.com and search proxy lists.

Browse Translation

1. Go to a website translation site, such as Babelfish or Google Translate
2. Enter the desired site in the translate URL box and choose an obscure language to translate into English.
3. Browse the site.

Host a PHP Proxy

1. On an unblocked computer, find a free PHP Host like Bravenet. Make sure it has FTP Support or a way to upload PHP scripts. Create an account.
2. On an unblocked computer, find a PHP Proxy script. There are many available and is usually just one file.
3. Upload the PHP Proxy script to your PHP Host and test it by executing the script from your browser.
4. To use it just type in the address of your script in your school.
5. As an example:If you went to Bravenet, your host might be youngone.bravenet.com.Upload your proxy i.e. "snake.php", and execute it by going to"youngone.bravenet.com/snake.php". That's it.

Disable the blocker

1. Some schools use proxy services (such as Bess) to do the filtering.It may be possible to disable it by going into Internet Explorer andchoosing Tools - Internet Options - Connections Tab - Lan Settingsand unchecking the "Use a proxy server for your LAN". It can bereenabled prior to leaving. In the likely event that this ability isdisabled, one can use a registry editor to change the value of"HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\InternetSettings\ ProxyEnable" to 0.
2. Hit the go button and you will get to your favorite site!
3. Check the sites that are blocked on your local computer.Open Internet Explorer, and select Tools - Internet Options. Clickthe "Security" tab and choose "Restricted Sites". The "Sites" buttonwill become available. Be sure that the site you wish to access is notlisted, if it is, highlight and delete it.
4. Lower the settings for your Internet security. This is not recommended for long periods of use, as this is how viruses and copycat programs infiltrate computers.
5. Install a filter-removing program.Many of these programs bypass the filter that is stopping you fromaccessing Myspace.com. Installing and using these programs may get youin serious trouble with your school or employer.

Browse with Ace VPN

1. Visit Ace VPN for account registration and installation instructions.

Browse using UltraSurf or JonDo (http:// download.cnet.com/JAP-JonDo/3000-2144_4-167235.html)

1. Click on the link.
2. Download the Ultrasurf 9 client software (in zipped or exe format) or JonDo in exe format.
3. Unzip the software using either WinAce, Winzip or WinRAR.
4. Ultrasurf and JonDo are green software and don't require installation. Simply execute U[version].exe example: U86.exe, U87.exe or JonDo.exe
5. The software will tryto connect to proxy servers and will open a default web page in yourdefault browser upon successful connection.
6. The software will work on any installed browsers.
7. If you can't download it from school, put the executable on a flash drive at home and run it off there.

Browse with a "Portable" Browser

1. Visit mozilla.com or the site of another browser such as Opera.
2. Search for a portable version of the browser. This should be a download with a "pre-installed" copy of the browser, using regular files to store settings.
3. Run the portable version and enjoy.
4. Set an http proxy in the portable browser if needed. Visit Proxy list for daily updated proxies.

Browse with remote access

1. Leave a computer always on at home (and connected to the internet). Turn on remote access.
2. On the school computer go to Start - Accessories - Remote Desktop Connection.Put in your IP address (or sign up your computer at home for dyndns.orgto get a name for it if your address changes all the time). You canconnect to your home computer, and do anything you want from there.
3. You can also use a VNC service.

Browse with text editors

1. Open notepad. Start menu - programs - accessories - notepad OR %SystemRoot%system32notepad.exe
2. File - Open and in the "File Name" field, enter the IP address of the website you'd like to visit WITH the http:// or https:// prefixes. (See above for procedure to attain IPs.)
3. File - Save As and save the file as an .htmlfile. Open it in MS WORD as a HTML Webpage. (you can directly downloadthe file with MS WORD but some schools block MS OFFICE from all networkaccess as PowerPoint used to be able to browse folders the user was notauthorized to access as it ran in Shell 0 instead of Shell 1.)

my $basedir = "/cgi-bin/webpath/to/server/program/server_program_name";