As soon as you've setup a Linux instance on Amazon EC2 you're likely next step is to get FTP access so you can move files about.
If, like me, your FTP tool of choice is FileZilla then this tip might save you some of the time it took me to work it out.
First of all make sure port 22 is open in your instance's Security Group in Amazon's AWS site. You can test this from a Terminal using the following command:
If that times out then most likely port 22 isn't open. Otherwise you're ok. SFTP uses the same port so we can carry on and set it up.
If at this point you try to connect using SFTP from FileZilla you'll probably see this:
The error is "No supported authentication methods available". To get round it you need to tell FileZilla about the .PEM file that was created when you built the Amazon instance. Assuming you already downloaded it to you PC, open FileZilla and select the Edit->Settings menu.
Click the "Add key file..." button and locate your PEM file. At this point FileZilla will ask if you want to convert it to a format it can use. Say yes and tell it where to put the new .PPK file. Once this is done press ok and try to connect again. You should have more luck!