The deny_info option is a directive in the Squid configuration file, which can be used to:
Present clients with a custom access denied page.
Redirect (HTTP 302) the clients to a different URL, displaying more information about why access was denied or containing help messages.
Reset the TCP connection.
Let's have a look at the three syntaxes of the deny_info directive:
deny_info CUSTOM_ERROR_PAGE ACL_NAME deny_info ALTERNATE_URL ACL_NAME deny_info TCP_RESET ACL_NAME
The syntaxes shown previously correspond to the uses we have just discussed. In the first syntax, the parameter CUSTOM_ERROR_PAGE specifies a custom error page written in HTML or plain text, which will be displayed instead of Squid's default access denied page. The error page written in English should be placed in the ${prefix}/share/errors/en-us/ directory or another appropriate location for other languages. We can also place this errors file in a custom location such as /etc/squid/local-errors...