Install Squid proxy

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Squid is the most popular Proxy server for Linux systems. The squid proxy server is also useful for the web packet filtering.

Install Squid

Squid packages are available in default yum repositories.

yum install squid

Configuring Squid

nano /etc/squid/squid.conf
    #
    # Recommended minimum configuration:
    ## Example rule allowing access from your local networks.
    # Adapt to list your (internal) IP networks from where browsing
    # should be allowed
    acl localnet src 10.0.0.0/8     # RFC1918 possible internal network
    acl localnet src 172.16.0.0/12  # RFC1918 possible internal network
    acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
    acl localnet src fc00::/7       # RFC 4193 local private network range
    acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged)

    machinesacl 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#
    # Recommended minimum Access Permission configuration:
    #
    # Deny requests to certain unsafe ports
    http_access deny !Safe_ports# Deny CONNECT to other than secure SSL ports
    http_access deny CONNECT !SSL_ports# Only allow cachemgr access from localhost
    http_access allow localhost manager
    http_access deny manager# We strongly recommend the following be uncommented to protect innocent
    # web applications running on the proxy server who think the only
    # one who can access services on "localhost" is a local user
    #http_access deny to_localhost#
    # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
    ## Example rule allowing access from your local networks.
    # Adapt localnet in the ACL section to list your (internal) IP networks
    # from where browsing should be allowed
    http_access allow localnet
    http_access allow localhost# And finally deny all other access to this proxy
    http_access deny all# Squid normally listens to port 3128
    http_port 3128# Uncomment and adjust the following to add a disk cache directory.
    #cache_dir ufs /var/spool/squid 100 16 256# Leave coredumps in the first cache dir
    coredump_dir /var/spool/squid

# # Add any of your own refresh_pattern entries above these.
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

Allow IP Address to Use the Internet Through Your Proxy Server

If your netwok is 110.220.330.0/24:

acl localnet src 110.220.330.0/24

For changes to take effect you will need to restart your Squid server, use the following command for same.

systemctl restart squid

Allow a Specific Port for HTTP Connections

acl Safe_ports port 8080

Using Basic Authentication with Squid

yum -y install httpd-tools
touch /etc/squid/passwd && chown squid /etc/squid/passwd

htpasswd /etc/squid/passwd proxyuser
    New password:
    Re-type new password:
    Adding password for user pxuser

nano /etc/squid/squid.conf
...
auth_param basic program /usr/lib64/squid/basic_ncsa_auth /etc/squid/passwd
auth_param basic children 5
auth_param basic realm Squid Basic Authentication
auth_param basic credentialsttl 2 hours
acl auth_users proxy_auth REQUIRED
http_access allow auth_users

Blocking Websites

nano /etc/squid/blocked_sites
facebook.com
youtube.com

nano /etc/squid/squid.conf
acl blocked_sites dstdomain "/etc/squid/blocked_sites"
http_access deny blocked_sites

Block Specific Keyword with Squid

nano /etc/squid/blockkeywords.lst
yahoo
gmail
facebook

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

Disable caching

# Leave coredumps in the first cache dir
#coredump_dir /var/spool/squid

Changing Squid Port

nano /etc/squid/squid.conf
http_port 3128

Export Proxy Server Settings

$ export http_proxy="http://PROXY_SERVER:PORT"
$ export https_proxy="http://PROXY_SERVER:PORT"
$ export ftp_proxy="http://PROXY_SERVER:PORT"

$ export http_proxy="http://USER:PASSWORD@PROXY_SERVER:PORT"
$ export https_proxy="http://USER:PASSWORD@PROXY_SERVER:PORT"
$ export ftp_proxy="http://USER:PASSWORD@PROXY_SERVER:PORT"

Test caching

env | grep proxy

tailf /var/log/squid/access.log