Dear MPICH. I'm using mpich 3.1 (hydra+MPI). I execute main application (Main) which calls mpiexec.hydra in following way: mpiexec.hydra -genvall -disable-auto-cleanup -f MpiConfigMachines.txt -launcher=ssh -n 3 MPI_Prog MpiConfigMachines.txt content: 10.3.2.100:1 10.3.2.101:2 Where 10.3.2.100 is a local host. As result I get - Main + single MPI_Prog processes on local computer - 2 MPI_Prog processes on remote one. Main application establish TCP socket with local MPI_Prog. Main application establish TCP socket with controller on other computer 10.3.2.170, which is not included in MpiConfigMachines.txt file. After executing some time (hours, sometimes days) I see via netstat that created new connection from mpiexec.hydra and controller. Before executing mpiexec.hydra I set environment variable setenv MPIEXEC_PORT_RANGE 50010:65535 According to manual this variable limits hydra destination ports to [50010:65535]. I see that hydra uses these ports with MPI_Prog, but connection with controller done on port 701 (controller computer). Controller program is a server. It can accept connections only. Can you please advice how to stand with this problem? How hydra recognizes controller IP and establish connection with it? Sincerely, Anatoly. _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss