Hack The Sec-Leading Resource Of Linux Tutorial: squide_transparent

<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 class="post-heading" style="background-color: white; border: 0px; font-family: sans-serif; font-size: 24px; line-height: 30px; margin: 30px 0px 15px; opacity: 1; outline: 0px; padding: 0px; transition: opacity 0.24s ease-in-out; vertical-align: baseline; visibility: visible;">
<span style="color: red;">Configure Squid 3.x as Transparent Proxy on CentOS 7 / RHEL 7</span></h2>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">There are several benefits of using a transparent proxy. First of all, for end users, a transparent proxy can enhance their web browsing performance by caching frequently accessed web content, while introducing minimal configuration overhead for them. For administrators, it can be used to enforce various administrative policies such as content/URL/IP filtering, rate limiting, etc.</span></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1VrRyKPmaAN8_k1ni3Alq0RVqEPZim4tvw83TXom35GD6ZGJrboNOHhJ97rT251n4G6I7iWctMMqdO5wN9jm5mrF3yErWGe65h2lNz-DioH6G_eOWTR2IFdWRyI2pi9EiwY8B7F-8CN0J/s1600/squid-installation-hackthesec.co.in.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1VrRyKPmaAN8_k1ni3Alq0RVqEPZim4tvw83TXom35GD6ZGJrboNOHhJ97rT251n4G6I7iWctMMqdO5wN9jm5mrF3yErWGe65h2lNz-DioH6G_eOWTR2IFdWRyI2pi9EiwY8B7F-8CN0J/s1600/squid-installation-hackthesec.co.in.jpg" /></a></div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><br /></span></span></div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">A proxy server acts as an intermediary between a client and a destination server. The client sends requests to the proxy server which then evaluates the requests and takes necessary actions. In this tutorial, we will be setting up a web proxy server using Squid, which is a robust, customizable and stable proxy server. Personally, I had administered a Squid server with 400+ client workstations for about a year. Although I had to restart the service about once a month in average, CPU and storage utilization, throughput and client response time were all great.</span></span></div>
<div>
<span style="color: #0b5394; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><b><u>Squid Installation and Configuration</u></b></span></span></div>
<div>
<pre style="background: rgb(54, 54, 54); border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># yum install squid –y</span></span></pre>
</div>
<div>
<div style="color: #333333; font-family: verdana, geneva, sans-serif; font-size: 15px; line-height: 26px;">
Edit squid configuration file</div>
<div style="color: #333333; font-family: verdana, geneva, sans-serif; font-size: 15px; line-height: 26px;">
Before you edit default configuration file it is highly recommended to keep backup.</div>
<div>
<pre style="background-attachment: initial; background-clip: initial; background-color: #363636; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># cp /etc/squid/squid.conf /etc/squid/squid.conf.bk-26-05-2016</span></span></pre>
</div>
</div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Open configuration file and add below mentioned parameters</span></span></div>
<div>
<pre style="background: rgb(54, 54, 54); border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># vi /etc/squid/squid.conf</span></span></pre>
</div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Add transparent proxy setting and add and allow our network</span></span></div>
<div>
<pre style="background: rgb(54, 54, 54); border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># vi /etc/squid/squid.conf</span></span></pre>
<pre style="background: rgb(54, 54, 54); border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># Allow LAN Network
acl our_network src 192.168.2.0/24

# Allow Network ACL Allow/Deny Section#
http_access allow our_network

# Transparent Proxy Parameters
http_port 3128 intercept

visible_hostname pxy.hackthesec.co.in</span></span></pre>
</div>
<div>
<div style="color: #333333; font-family: verdana, geneva, sans-serif; font-size: 15px; line-height: 26px;">
Save & Exit</div>
<div style="color: #333333; font-family: verdana, geneva, sans-serif; font-size: 15px; line-height: 26px;">
Now start squid service and make sure it is added on startup.</div>
<div>
<pre style="background-attachment: initial; background-clip: initial; background-color: #363636; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;"># systemctl start squid
# systemctl enable squid</span></span></pre>
</div>
</div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Add necessary iptables rules to setup squid as transparent proxy.</span></span></div>
<div>
<pre style="background-attachment: initial; background-clip: initial; background-color: #363636; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;">ptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to 192.168.2.100:3128
iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 3128
iptables --t nat -A POSTROUTING --out-interface eth1 -j MASQUERADE</span></span></pre>
</div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Now you can save your iptable rules by following command:</span></span></div>
<div>
<pre style="background-attachment: initial; background-clip: initial; background-color: #363636; background-image: initial; background-origin: initial; background-position: initial; background-repeat: initial; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 7px; border: 1px solid rgb(221, 221, 221); font-stretch: inherit; margin-bottom: 15px; margin-top: 15px; overflow-x: auto; overflow-y: hidden; padding: 18px 20px; vertical-align: baseline;"><span style="color: white; font-family: Monaco, Courier New, DejaVu Sans Mono, Bitstream Vera Sans Mono, monospace; font-size: medium;"><span style="line-height: 19px; white-space: pre-wrap;">service iptables save</span></span></pre>
</div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">That’s It, Now squid should work smoothly in transparent proxy mode.</span></span></div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><br /></span></span></div>
<div>
<span style="color: #333333; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><a href="http://www.hackthesec.co.in/">www.hackthesec.co.in</a></span></span></div>
</div>