  Context. 55 Cancri hosts five known exoplanets, most notably the hot
super-Earth 55 Cnc e, which is one of the hottest known transiting
super-Earths. Aims. Due to the short orbital separation and host star
brightness, 55 Cnc e provides one of the best opportunities for studying
star-planet interactions (SPIs). We aim to understand possible SPIs in this
system, which requires a detailed understanding of the stellar magnetic field
and wind impinging on the planet. Methods. Using spectropolarimetric
observations, and Zeeman Doppler Imaging, we derive a map of the large-scale
stellar magnetic field. We then simulate the stellar wind starting from the
magnetic field map, using a 3D MHD model. Results. The map of the large-scale
stellar magnetic field we derive has an average strength of 3.4 G. The field
has a mostly dipolar geometry, with the dipole tilted by 90 degrees with
respect to the rotation axis, and dipolar strength of 5.8 G at the magnetic
pole. The wind simulations based on this magnetic geometry lead us to conclude
that 55 Cnc e orbits inside the Alfv\'en surface of the stellar wind, implying
that effects from the planet on the wind can propagate back to the stellar
surface and result in SPI.
