Connecting to my Amazon EC2 image (from which this site is running) from Mac Os X took ages to find out and turned out to be relatively simple with the correct information (isn’t that always the case). At first I didn’t think the builtin Mac OS X ssh could cut it so I started looking into various Mac OS X ssh clients (Fugu, RBrowser, CyberDuck etc ..) but none of those could handle the Amazon public/private key encryption. Then I started looking into using Putty on Mac OS X even though thats not available for Mac OS X (but with a little help from MacPorts). That bombed on problems with GTK1. Dang, what to do?
Finally I found the correct information in a blog post, you need to use Puttygen to convert the Amazon .ppk file to OpenSSH format. The OpenSSH format can be used by the Mac OS X (OpenSSH) ssh client. You also need to chmod the direcory where you store the OpenSSH key so it will only allow read access to other users.
After that a simple text file with the following content:
ssh -2 -i /Users/xxxxx/amazon_ssh.key firstname.lastname@example.org
And save it in the Desktop area to have it available on your desktop (or save it elsewhere, whatever you like).