SQUID is a Proxy server and also used for web filtering. Its widely used for increasing web server speed by caching repeated data.

Below will show you to Install and Configure SQUID Proxy Server on CentOS/RHEL 7 Linux systems.

1. Install Squid

Squid can be easily install using yum command line tool.

# yum install squid

2. Setup Port and Start Service

Squid by default run on port 3128. If you want to start squid on different port, Edit squid configuration file and change http_port value. For example we are changing squid to run on port 8080.

# vim /etc/squid/squid.conf
http_port 8080

Start/Restart Squid service.

# service squid restart

3. Change iptables for the SQUID service port

For example, add the line below to /etc/sysconfig/iptables to open port 8080,

iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 8080 -j ACCEPT

More iptables examples, check iptables useful examples

4. Configure SQUID to Block Specific Website

Add below rules to block specific website before any allow all rules. Below example will block yahoo.com and www.fibrevillage.com.

acl blocksite1 dstdomain yahoo.com
acl blocksite2 dstdomain www.fibrevillage.com
http_access deny blocksite1
http_access deny blocksite2

If you have a long list of domain names, Create a file /etc/squid/blockwebsites.lst and put domain names one per line and add below rule in squid configuration file.

acl blocksitelist dstdomain "/etc/squid/blockwebsites.lst"
http_access deny blocksitelist

blockwebsites.lst file content example:

# cat /etc/squid/blockwebsites.lst
yahoo.com
www.fibrevillage.com

5. Configure Squid to Block Specific Keyword

Add below rules to block specific website before any allow all rules. Below example will block all pages having keyword yahoo or gmail.

acl blockkeyword1 url_regex yahoo
acl blockkeyword2 url_regex gmail
http_access deny blockkeyword1
http_access deny blockkeyword2

If you have a long list of keywords, Create a file /etc/squid/blockkeywords.lst and put keywords one per line and add below rule in squid configuration file.

acl blockkeywordlist url_regex "/etc/squid/blockkeywords.lst"
http_access deny blockkeywordlist

blockkeywords.lst file content example:

# cat /etc/squid/blockkeywords.lst
yahoo
gmail
twitter facebook
fibrevillage

All done !