Hello, I think It should be considered to change default remote shell which mpd is using to ssh. It's rsh now but I think most people are using ssh over rsh nowadays. People want to use clear commands like mpirun , not mpirun -r ssh... or something even more complicated. AFAIK there was no easy way to change that default easily in impi < 4.0. But in impi 4.0 there is a new environment I_MPI_MPD_RSH. How this should be used? Is it enough to set itI_MPI_MPD_RSH=ssh to have ssh as default remote shell (finally :) )? I would appreciate any working tips how to set ssh by default in impi < 4.0 BTW. did anybody try to replace successfullyrshCmd = 'rsh' torshCmd = 'ssh' in def mpdboot in/path/to/impi/3.x.x/bin/mpdboot?