Access list rules

In the previous section, we learned about ACL lists in detail. However, as we saw, ACL lists can only be used to identify, and that is only of use if they are combined with some access rules to control access to various components of our proxy server. Squid provides a lot of access list rules, with http_access being the most widely used.

As we have learned in Chapter 2, when we have multiple access rules, Squid matches a particular request against them from top to bottom and keeps doing so until a definite action (allow or deny) is determined. We also learned that if we have multiple ACLs within a single access rule, then a request is matched against all the ACLs from left to right and Squid stops processing the rule as soon as it encounters an ACL that can't identify the request. An access rule with multiple ACLs results in a definite action only if the request is identified by all the ACLs used in the rule.

Now, let's have a brief look at the different access list rules...