How to Detect Middleboxes : Guidelines on a Methodology

Internet middleboxes such as VPNs, firewalls, and proxies can significantly change handling of\udtraffic streams. They play an increasingly important role in various types of IP networks. If end\udhosts can detect them, these hosts can make beneficial, and in some cases, crucial improvements\udin security and performance But because middleboxes have widely varying behavior and effects\udon the traffic they handle, no single technique has been discovered that can detect all of them.\udDevising a detection mechanism to detect any particular type of middlebox interference involves\udmany design decisions and has numerous dimensions. One approach to assist with the\udcomplexity of this process is to provide a set of systematic guidelines. This paper is the first\udattempt to introduce a set of general guidelines (as well as the rationale behind them) to assist\udresearchers with devising methodologies for end-hosts to detect middleboxes by the end-hosts.\udThe guidelines presented here take some inspiration from the previous work of other\udresearchers using various and often ad hoc approaches. These guidelines, however, are mainly\udbased on our own experience with research on the detection of middleboxes. To assist\udresearchers in using these guidelines, we also provide an example of how to bring them into\udplay for detection of network compression. \u