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content/notes/Connect_MPI_system_over_SSH_for_Dummy.md

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+---
+tags:
+  - General
+title: Connect MPI system over SSH for Dummy
+description: How to setup MPI system over SSH
+date: 2025-01-01
+author: Nikola Petrov
+draft: false
+---
+
+1. On all computers
+```
+sudo apt install openssh-client
+sudo apt install openssh-server
+sudo apt install openmpi-bin libopenmpi-dev
+```
+
+2. Disable firewall
+```
+sudo ufw status
+sudo ufw disable
+```
+
+3. Try connecting master to every slave ( you will need password )
+```
+ssh user@ipslave1
+ssh user@ipslave2
+```
+
+4. On master generate a key and put it on the slaves
+```
+ssh-keygen -t rsa
+
+ssh-copy-id user@ipslave1
+ssh-copy-id user@ipslave2
+```
+
+5. Try connecting master to every slave ( you will not need password )
+```
+ssh user@ipslave1
+ssh user@ipslave2
+```
+
+6. Compile program 
+```
+mpicc main.c -o main
+mpic++ main.cpp -o main
+```
+
+7. Copy main in to /tmp folder for easy same location ( program needs to be in the same path on all computers )
+```
+cp /path/to/main /tmp/mympiprogram/
+```
+
+8. Copy program to all computers
+	- Could use NFS server for auto copy
+```
+scp <source> <destination>
+scp /tmp/mympiprogram/main user@ipslave1:/tmp/mympiprogram/main
+scp /tmp/mympiprogram/main user@ipslave2:/tmp/mympiprogram/main
+```
+
+
+9. Run program
+	- `num < c1 + c2 + c3` 
+	- c1 is number of processes that can run on the computer
+	- num is number of processes that are needed for the program
+``` 
+mpirun -np <num> --host 127.0.0.1:<c1>,ipslave1:<c2>,ipslave2<c3> /tmp/mympiprogram/main
+```
+
+10. Enable firewall
+```
+sudo ufw status
+sudo ufw enable
+```
+
+
+
+