Welcome guys to this very tutorial on how to install and configure Squid proxy on Fedora 29/Fedora 28/CentOS 7.
Squid is a full-featured web proxy cache server application which provides proxy and cache services for HTTP, FTP, SSL requests and DNS lookups. It also performs transparent caching that reduces bandwidth and improves response time by caching and reusing frequently requested web pages.
Install and Configure Squid Proxy on Fedora 29/Fedora 28/CentOS 7
Squid proxy is available on both Fedora and CentOS default repositories and can be installed by running the command below.
dnf install squid -y << Fedora or yum install squid -y << Fedora/CentOS
Once the installation is done, start and enable squid to run in system start.
systemctl start squid systemctl enable squid
When run, squid listens on port 3128 by default on all network interfaces on the machine. You can however change this by replacing the port number on
http_port directive to your respective port number on the squid proxy configuration file,
/etc/squid/squid.conf. For example, to use port 8080,
... # Squid normally listens to port 3128 # http_port 3128 << comment the default port http_port 8080 ...
The default squid configuration file is located at
/etc/squid/squid.conf. This configuration file contains the minimum recommended configuration options.
In order to make your own configuration customization, you can make a copy of the original configuration file.
cp /etc/squid/squid.conf /etc/squid/squid.conf.bak
The default squid configuration file without comments looks like;
acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN) acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN) acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN) acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN) acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN) 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 # http_access deny !Safe_ports http_access deny CONNECT !SSL_ports http_access allow localhost manager http_access deny manager http_access allow localnet http_access allow localhost http_access deny all http_port 3128 coredump_dir /var/spool/squid refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern . 0 20% 4320
Configure Squid Access Control List
In order to allow a specific network or CIDR ranges to access Internet through proxy server, you need to define an ACL for the same network. For example to allow hosts in the 192.168.56.0/24 network to access internet through our proxy server, edit the
/etc/squid/squid.conf configuration file and add an ACL entry as shown below.
... # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # acl internal src 220.127.116.11/24 # Allow Internal hosts ...
Next, you need to allow access from the network based on your defined ACL above.
... # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # acl internal src 18.104.22.168/24 # Allow Internal hosts http_access allow internal ...
Blocking Specific Websites
Squid proxy can be used to restrict access to specific websites. For example to block access to youtube, facebook, netflix you would have to create a file that defines the domains of these websites as shown below;
.youtube.com .facebook.com .netflix.com
After that, created an ACL for the restricted sites above in the squid configuration file. After that, set the deny rule for the defined rule.
... # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # acl internal src 22.214.171.124/24 # Allow Internal hosts acl blockedsites dstdomain "/etc/squid/restricted-sites.squid" # For restricted sites http_access deny blockedsites http_access allow internal ...
Block Sites based on Specific Keywords
Just like how you block a website based on a domain, you can also restrict access to a website by the use of a keyword. Create a file with specific keywords.
porn ads movie gamble
Make the necessary changes on squid configuration file.
... # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # acl internal src 126.96.36.199/24 # Allow Internal hosts acl blockedsites dstdomain "/etc/squid/restricted-sites.squid" # For restricted sites <strong>acl keyword-ban url_regex "/etc/squid/keyword-ban.squid" </strong> http_access deny blockedsites <strong>http_access deny keyword-ban</strong> http_access allow internal ...
Masking Outgoing Traffic
As much as you use proxy server to anonymize your IP addresses by presenting the IP address of the proxy to other web servers, proxy servers may expose you by including your IP addresses on the outgoing HTTP requests. You can however disable this by including the following directives at the end of your squid configuration file.
... # refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern . 0 20% 4320 # Anonymize Traffic via off forwarded_for off request_header_access From deny all request_header_access Server deny all request_header_access WWW-Authenticate deny all request_header_access Link deny all request_header_access Cache-Control deny all request_header_access Proxy-Connection deny all request_header_access X-Cache deny all request_header_access X-Cache-Lookup deny all request_header_access Via deny all request_header_access X-Forwarded-For deny all request_header_access Pragma deny all request_header_access Keep-Alive deny all
Once you are done with the configuration, save the file and restart squid.
systemctl restart squid
If Firewalld is running, you need to allow squid proxy service.
firewall-cmd --add-service=squid --permanent firewall-cmd --reload
Configure Proxy Clients to connect to the Proxy server
To configure client to connect to the Internet through the squid proxy server, you can either set system wide proxy configurations, configure client to use the Squid proxy as the gateway and set the proxy settings on the browser.
System Wide proxy configuration
To set system wide proxy configurations, create a configuration file under
/etc/profile.d with environment variables defining squid proxy server details as follows;
PROXY_URL="192.168.43.70:3128" HTTP_PROXY=$PROXY_URL HTTPS_PROXY=$PROXY_URL FTP_PROXY=$PROXY_URL http_proxy=$PROXY_URL https_proxy=$PROXY_URL ftp_proxy=$PROXY_URL export HTTP_PROXY HTTPS_PROXY FTP_PROXY http_proxy https_proxy ftp_proxy
After that, source the new configuration file.
To test this, try to download anything from the clients terminal while tailing access logs on squid proxy server.
On the client’s terminal, run;
--2018-11-20 12:46:29-- http://google.com/ Connecting to 192.168.43.70:3128... connected. Proxy request sent, awaiting response... 301 Moved Permanently Location: http://www.google.com/ [following] --2018-11-20 12:46:29-- http://www.google.com/ Reusing existing connection to 192.168.43.70:3128. Proxy request sent, awaiting response... 200 OK Length: unspecified [text/html] Saving to: ‘index.html’ index.html [ <=> ] 11.59K 44.0KB/s in 0.3s 2018-11-20 12:46:30 (44.0 KB/s) - ‘index.html’ saved 
On the server;
tail -f /var/log/squid/access.log
1542327358.562 0 192.168.43.214 TCP_MEM_HIT/301 667 GET http://google.com/ - HIER_NONE/- text/html 1542327359.036 472 192.168.43.214 TCP_MISS/200 12756 GET http://www.google.com/ - HIER_DIRECT/188.8.131.52 text/html
Use Squid Proxy as the gateway and Configure Proxy Setting on the browser
To set Squid proxy as the default gateway, modify your interface configurations.
ip route add default via 192.168.43.70 dev enp0s3
nmcli con mod eth0 ipv4.gateway 192.168.43.70
To set proxy settings on browser, navigate to Preferences > General > Network Settings > Manual Proxy Configuration. Enter the proxy server details as shown b below. Be sure to check Use this proxy server for all protocols.
Trying to access Netflix on the browser;
On the server;
tail -f /var/log/squid/access.log
1542328269.419 0 192.168.43.214 TCP_DENIED/403 3995 CONNECT facebook.com:443 - HIER_NONE/- text/html 1542328289.684 0 192.168.43.214 TCP_DENIED/403 4080 GET http://netflix.com/ - HIER_NONE/- text/html 1542328289.820 0 192.168.43.214 TCP_HIT/200 13052 GET http://localhost.localdomain:3128/squid-internal-static/icons/SN.png - HIER_NONE/- image/png 1542328289.922 0 192.168.43.214 TCP_DENIED/403 4075 GET http://netflix.com/favicon.ico - HIER_NONE/- text/html
That is all about how to install and configure Squid proxy on Fedora 29/Fedora 28/CentOS 7.
In our next article, we will cover how to configure Squid proxy authentication. Thank you for reading.
We also covered how to set system wide proxy settings on Ubuntu 18.04 in our previous article.