How do I troubleshoot my ssh tunnel access after putting in my public key?

There are a few steps to help troubleshoot this problem.

Confirm that the key value for the user found in the 'Manage SSH Keys' section of the system administrator's page matches the value shown in /path/to/.ssh/id_dsa.pub. A simple 'cat' or viewing the key in a text editor should allow you to compare the two files.

If there is a match between those two values, the next step is to ensure the private key and public key are a true pair. A simple way to accomplish this is to validate the bubble-babble digest of the pair matches, which can be done this way:

ssh-keygen -B -f /path/to/.ssh/id_dsa 
            ssh-keygen -B -f /path/to/.ssh/id_dsa.pub

If those values don't match, the keys are most likely not a pair and you must either create a new pair and replace the public key on the site with the new one or find the appropriate private key to match the registered public key.