Hack The Sec-Leading Resource Of Linux Tutorial: proxy

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Block Facebook, Twitter and YouTube’s HTTPS Traffic In Squid Transparent Proxy Mode 
After setting up <a href="http://www.hackthesec.co.in/2016/05/how-to-configure-squid-3x-as.html" target="_blank">Squid As Transparent Proxy Mode</a>, most of the system admins try to block famous social media websites such as Facebook, Twitter and YouTube in their network.So in this guide we will learn how to Block HTTPS Traffic while Squid is running as Transparent Proxy. 
<a href="http://www.hackthesec.co.in/2016/05/how-to-configure-squid-3x-as.html" itemprop="url" style="background-color: white; display: block; font-family: 'Open Sans', serif, sans-serif; font-size: 18.6px; font-weight: 600; text-decoration: none;"></a> 
<ul style="text-align: left;">
<li><a href="http://www.hackthesec.co.in/2016/05/how-to-configure-squid-3x-as.html" itemprop="url" style="display: inline !important; font-size: 18.6px; text-decoration: none;">How to Configure Squid 3.x as Transparent Proxy on CentOS 7 / RHEL 7</a></li>
</ul>
 
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We understand now that 443 port traffic is passing through iptables firewall. So with the help of iptables string matching feature we will see how to block Facebook, Twitter and YouTube HTTPS traffic. 
Iptables Rule to Block Facebook in Squid Transparent Proxy Setup 
<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;">iptables -I FORWARD -p tcp --dport 80 -m string --string 'facebook.com' --algo bm --to 65535 -j DROP</pre>
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iptables -I FORWARD -p tcp --dport 443 -m string --string 'facebook.com' --algo bm --to 65535 -j DROP</pre>
Iptables Rule to Block Twitter in Squid Transparent Proxy Setup 
<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;">iptables -I FORWARD -p tcp --dport 80 -m string --string 'twitter.com' --algo bm --to 65535 -j DROP</pre>
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iptables -I FORWARD -p tcp --dport 443 -m string --string 'twitter.com' --algo bm --to 65535 -j DROP</pre>
Iptables Rule to Block YouTube in Squid Transparent Proxy Setup 
<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;">iptables -I FORWARD -p tcp --dport 80 -m string --string 'youtube.com' --algo bm --to 65535 -j DROP</pre>
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iptables -I FORWARD -p tcp --dport 443 -m string --string 'youtube.com' --algo bm --to 65535 -j DROP</pre>
Above rules will block entire traffic destine to 443 port but you can apply same rule on particular single ip, range of ips or complete network. 
To Apply Same Rule on Single IP Address 
<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;">iptables -I FORWARD -p tcp --dport 443 -s 192.168.2.10 -m string --string 'youtube.com' --algo bm --to 65535 -j DROP</pre>
To Apply Same Rule on Range of IP Addresses 
<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;">iptables -I FORWARD -p tcp --dport 443 -m iprange --src-range 192.168.2.11-192.168.2.15 -m string --string 'youtube.com' --algo bm --to 65535 -j DROP</pre>
Above rule will block YouTube.com only specified ips from 11 to 15 other all range is allowed. 
To Apply Same Rule on Whole Subnet of 192.168.2.0/24 
<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;">iptables -I FORWARD -p tcp --dport 443 -s 192.168.2.0/24 -m string --string 'youtube.com' --algo bm --to 65535 -j DROP</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;"><a href="http://www.hackthesec.co.in/">www.hackthesec.co.in</a></pre>
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