Use SCP and SFTP

With 7630cb9 , we began using SCP/SFTP to read and write IO configuration. Currently we can read and write IO configuration. In the future it is likely that we will use SCP to read status information, including traffic logs, from IO. Pros Simplicity. Nearly everyone has an SCP/SFTP client and can understand how to use it. Security. Access is secured by user SSH keys. The wish package makes this easy to add. Cons It's not an HTTP API, which some people might prefer.