linux - MPI run on external network -

i'm new mpi , wrote program calculate large factorials on multiple processors. tested program on local network 2 machine. ie. laptop , pc , working perfectly.

now trying run program on internet on friend's pc. installed perfectly. configure router port forwarding , can ssh user account.

i'm using mpicc compile program , works , copied executable file external machine through scp. problem when run command mpirun -hostfile hostlist -np 2 fname. process stucked , blinking cursor on terminal.

can explain me why happening? thanks.

as didn't provide code snippet,

i'll list may reason, there others too, best way debug code, , see stuck

the reasons can several

1. code issue, wrong handling of special cases

2. network issue, wrong configuration specific port, firewall configuration etc.

3. etc