The Internet is full of middleboxes that change packets and flows. In fact, there is probably no IP or TCP header that is not affected by at least one middlebox. Obviously, middleboxes impede path transparency, i.e., the idea that an exchange of messages results in more or less the same packets, no matter what path the packets takes. This in turn stifles innovation of new transport protocols and hinders adoption of ubiquitous encryption. Furthermore, no one seems to have a truly global view of what middleboxes do to packets on what Internet paths, which would however be an essential knowledge for new transport protocols to be successfully deployed.
We address these concerns in the MAMI project by building an observatory of path transparency measurements. The project hosts an extensive set of path transparency measure- ments — we believe it to be the first dataset to deal specifically with middlebox involvement.