I have a small network of machines all running the same OS (Linaro Ubuntu Linux); they were all cloned from the same disk image and differ only in their machine names (UNIT1 through UNIT4). I can ssh between them at will, trusty has been established and I no longer get asked for a password upon connecting. MPICH is installed from the Ubuntu repository (not quite the latest version: mpiexec reports version OpenRTE 1.8.1, the mpich package is 3.0.4-6ubuntu1), and I can run a demo like cpi with no issues, using a little mpi-run.sh bash script (the default shell is tcsh, however) : (begin script) #!/bin/bash set -e ESDK=${EPIPHANY_HOME} ELIBS=${ESDK}/tools/host/lib:${LD_LIBRARY_PATH} EHDF=${EPIPHANY_HDF} echo "Running cpi on machines.u2.mpi" LD_LIBRARY_PATH=${ELIBS} mpiexec --allow-run-as-root -machinefile /home/linaro/.machines.u2.mpi -n 1 /home/linaro/myMPI/cpi echo "Done!" (end script) .machines.u2.mpi consists of the one line: linaro@UNIT2