October 30 2011

EC2 SSH on the iPad with Panic Prompt

by Brian Dunagan

Update: EC2 SSH on the iPhone with Panic Prompt

Back in April, Panic shipped a beautiful SSH app for iPhone and iPad: Prompt. Quite a few comments on that announcement blog post concerned EC2. Many people wanted to SSH into their Amazon cloud, but they couldn’t figure out the keypair situation. A day later, Joe Cheng covered steps that worked for him. Unfortunately, his steps didn’t work for me. Here is what I did:

1. Buy Prompt. I'm using v1.2.2.
2. Find your keypair file. This is not the .pem file. This is the one you use to SSH into your instances without a password: ssh -i path/to/keypair_file name@ip_address.
3. Duplicate that keypair file. I named it aws.
4. Look at the duplicated file. Mine contained the key signature as the first line. (See below.) Remove the key signature. Prompt doesn't like it.

   KEYPAIR	keypair-name	12:34:56:78:90:12:34:56:78:90:12:34:56:78:90:12:34:56:78:90
   -----BEGIN RSA PRIVATE KEY-----
   ...key...
   -----END RSA PRIVATE KEY-----

5. Sync your iOS device with iTunes, click on "Apps", scroll down, and find "File Sharing".
6. Click on Prompt in the list of apps, click "Add...", select the duplicate keypair file (aws), and add it.
7. Sync your iOS device again to transfer the files over.
8. Launch Prompt. You'll see a little key icon next to "Password". Tap it.
9. As soon as you tap the key icon, you should see a list of keys (and not the yellow popup). My list has "None" and "aws". Looking back at iTunes, you'll notice the keypair file is no longer listed in "Prompt Documents".
10. No need to worry about generating a public key with ssh-keygen.

As a bonus, I found this great tip on using screen to create or reattach to a terminal session: screen -DDRS ios.