Dropbox is a free in-the-cloud file storage and synchronization service providing both web and smart application interfaces. Note: any dropbox traffic that is encrypted will be classified as dropbox and not dropbox_upload or dropbox_download. Dropbox file upload/download can occur across multiple sessions, so a Q_MPA_FILE_GEN_* attribute can be raised in multiple flows for the same file. User applications can correlate extracted attributes using Dropbox's Q_MPA_FILE_GEN_ID attribute.