  Man-in-the-Middle (MM) is not only a ubiquitous attack pattern in security,
but also an important paradigm of network computation and economics.
Recognizing ongoing MM-attacks is an important security task; modeling
MM-interactions is an interesting task for semantics of computation. Traced
monoidal categories are a natural framework for MM-modelling, as the trace
structure provides a tool to hide what happens *in the middle*. An effective
analysis of what has been traced out seems to require an additional property of
traces, called *normality*. We describe a modest model of network computation,
based on partially ordered multisets (pomsets), where basic network
interactions arise from the monoidal trace structure, and a normal trace
structure arises from an iterative, i.e. coalgebraic structure over terms and
messages used in computation and communication. The correspondence is
established using a convenient monadic description of normally traced monoidal
categories.
