Squid usually is dependent on OpenSSL. If OpenSSL is not installed on your system, install OpenSSL.

apt-get install openssl
yum install openssl

Installing Squid on Linux is incredibly easy. Simply use apt-get or yum to install squid.

apt-get install squid3
yum install squid

The ps command can be used to determine if your system is using init or systemd. If PID 1 is init, then you will use the service command. If PID 1 is systemd, then you will use the systemctl command.

If your system is using systemd, use the systemctl command to start and enable squid.

systemctl enable squid
systemctl start squid
systemctl status squid

If your system is using init, use the chkconfig and service commands to start and enable squid.

chkconfig squid on
service squid start
service squid status

Allow port 3128 in iptables or firewalld.

You can now configure Squid as a web proxy server or as a transparent proxy server.