Access controls in reverse proxy mode
When Squid is configured in reverse proxy mode or our proxy server is acting as a surrogate, it'll be accepting requests from all over the Internet. In this case, we can't form a list of clients or subnets to allow access to HTTP via our proxy server, as we did in forward proxy mode. However, we'll have to make sure that our proxy server doesn't accept requests for origin servers that we are not accelerating.
We should note that we'll have to be clever while constructing access rules when we are using the same Squid instance for reverse proxying as well as forward proxying. We'll have to allow access to foreign origin servers so that our clients can access foreign websites using our proxy server. Later, we'll have a look at the access control configuration for various types of setups.
Squid in only reverse proxy mode
When we have configured Squid to work only as a reverse proxy, we need to restrict access to the origin server which we are accelerating....