OAuthServer on CakePHP Amazon EC2 - Incorrect Signature

I'm running an OAuth server on with CakePHP. My server works fine hosted on dreamhost, but when I move the identical code to Amazon EC2, I get "Invalid Signature" problems. What server configuration setti开发者_运维问答ngs could might break OAuth's functionality?

I fixed the problem. The OAuth server was running on port 81 (rather than 80), so I had to append :81 to the end of the url (http://api.example.com:81). I changed the port to 80, to leave it off the URL, and it fixed the "invalid signature" error.