  In this work the non-equilibrium dilepton production from a hadronic
transport approach (SMASH) is presented. The dilepton emission from the
hadronic stage is of interest for current HADES results measured at GSI in the
beam energy range from 1.25 - 3.5 GeV. Also at high collision energies
(RHIC/LHC) the later dilute stages of the reaction are dominated by hadronic
dynamics. The newly developed hadronic transport approach called SMASH
(=Simulating Many Accelerated Strongly-interacting Hadrons) is introduced
first. After explaining the basic interaction mechanisms, a comparison of
elementary cross sections for pion production to experimental data is shown.
The dilepton production within SMASH is explained in detail. The main
contribution to the dilepton spectra in the low energy regime of
GSI/FAIR/RHIC-BES originates from resonance decays. Results of the dilepton
production with SMASH such as invariant mass spectra are shown.
