Test "Transparent connection"

This test checks whether a direct (unchanged) transmission of data between test-client and test-server is possible, or whether an intervening entity (middlebox e.g. proxy) changes the request. In the course of this test requests are sent, which typically cannot be forwarded correctly by middleboxes and therefore changes can be identified.
If the connection is not transparent, it cannot be guaranteed that websites correspond exactly with those on the server. Such proxy requests typically buffer and possibly transmit antiquated or incomplete content. According to their set-up such proxy servers can also be used to filter or alter content (e.g. compact videos or pictures).