To be able to ssh to a remote Linux system without entering your password, carefully follow these steps:
ls -alto see if you have a .ssh directory in your home directory.
ls -alIf the permissions on your .ssh directory are anything besides 700 (i.e., drwx------, meaning for this directory, you and only you can read, write, and execute in it), make the .ssh directory secure by entering:
chmod 700 .ssh
ssh-keygen -t rsaThe ssh-keygen program will prompt you three times:
ls -alYou should see two new files:
cat id_rsa.pub >> authorized_keysThis appends your public key to the authorized_keys file, which tells ssh to authenticate you using your key, instead of making you enter a password.
(Alternatively, you can just copy your public key and paste it into the authorized_keys file using a text editor, so long as the editor does not insert extra control characters when it pastes.)
ls -alIf the permissions on id_rsa or authorized_keys are anything besides 600 (i.e., -rw-------), enter:
chmod 600 id_rsaand/or
chmod 600 authorized_keysThis will ensure that only you can read from or write to a given file.
When you have completed these steps, the first time you ssh to a particular lab machine, you will be prompted to accept and cache its hostkey in your ~/.ssh/known_hosts file. You just have to do this once per machine; after that, ssh will see the host's name in the known_hosts file and let you ssh to it without any interaction.
Because your home directory (containing .ssh) is shared by our ulab machines, the preceding steps should allow you to ssh from any ulab machine to any other ulab machine without being prompted for a password.
However, your home directory is not shared on our cluster, so it will be unable to read your key from your .ssh folder. To fix this, we just have to get your public key from your authorized_keys file in the ulab into your authorized_keys file on the cluster.
To do this securely, follow the steps in this video created by Chris Wieringa. It shows you how to use an information management system called FreeIPA to securely tranfer your public key to the cluster without you having to login there. For convenience, here is a link to our FreeIPA server.
When you have completed the steps in the video, test it out by trying to ssh to the cluster, for example:
ssh -p 22122 yourUserName@dahl.calvin.edu(Be sure you replace yourUserName with your user name.)
Note that the first time you do so, you will have to confirm that you want to add the cluster to your known_hosts file, as was the case in the ulab. Note also that for added security, we are using a non-standard port  for ssh instead of port 22.
If you have followed the steps correctly, you should now be able to ssh and/or transfer files to the cluster from a ulab machine without entering your password -- congratulations!
Be sure you have this working before proceeding further.
If you experience difficulty getting this to work, please contact Chris Wieringa or Prof. Adams.