Listing 3 Example from squid.conf

http_access deny !Safe_ports
   #-->This explicitly denies access to TCP ports other than Safe_ports
   # lists of ports. (! used for negation)
http_access deny CONNECT !SSL_ports
   #-->In general squid can issue connect() call to remote webserver and
   # handover connection to client browser without worrying about
   # caching and all(i.e squid will not act as a full time proxy,
   # except manipulating IP headers for proper routing). For SSL
   # connection squid uses such method as squid won't be knowing all
   # encryption details between browser and https server. This acl says
   # do not use connect() to ports other than SSL_ports (defined   
   # earlier) and connection will not be passed as it is to browser,
   # rather squid will handle those connection itself and act as a full
   # time proxy for any request from client browser.

#### ADD YOUR SITE SPECIFIC RULES HERE NOW #####

http_access deny all
   #This denies any http request as a last rule.