title: Open MPI, contact information is unknown
body: <p>I am working on Mac OSX and using bash as my shell. I have been working for the past few hours trying to get the <a href="http://www.mpitutorial.com/mpi-hello-world/" rel="nofollow">simplest</a> of code to run using Open MPI on multiple computers. After fiddling with configuring Open MPI, I believe I am on the verge of getting the thing to work. However, I have hit a dead end.</p>
  
  <p>The code runs fine without asking other computers over the internet to run it (meaning, I can run it using Open MPI on my own desktop), but when I put in a hostfile and ask a host to run the code I get an error. I think I am connecting to the host fine otherwise, I can ssh to them and do whatever I want, it's just when I run the code. </p>
  
  <p>To produce the following error I run: <code>mpirun -n 4 -hostfile /path/hostfile.txt ./mpi_hello_world</code>. Then it ask for the password on the host I am access, I enter it and then receive the following:</p>
  
  <pre><code>[MyComputer] [[62774,0],0] ORTE_ERROR_LOG: A message is attempting to be sent to
  a process whose contact information is unknown in file /opt/local/var/macports/
  build/_opt_mports_dports_science_openmpi/openmpi/work/openmpi-1.7.1/orte/mca/rml/
  oob/rml_oob_send.c at line 362
  
  [MyComputer] [[62774,0],0] attempted to send to [[62774,0],1]: tag 15
  
  [MyComputer] [[62774,0],0] ORTE_ERROR_LOG: A message is attempting to be sent to 
  a process whose contact information is unknown in file /opt/local/var/macports/
  build/_opt_mports_dports_science_openmpi/openmpi/work/openmpi-1.7.1/orte/mca/
  grpcomm/base/grpcomm_base_xcast.c at line 166
  </code></pre>
  
  <p>Would anyone be able to give me an idea of what is going wrong here? Thanks for any insight you can offer.</p>