I'm confused by the title and the question.
What does dropbox or google docs have to do with FTP?
Are you asking how to capture the dropbox/google docs username? If so, thats not something that's documented... is there a purpose/background why you want something like this?
Or are you asking how to capture the authenticated username when they access a dropbox/google docs URL, if so this should already be logged as you found.
Sorry Jon for not being clear.
Kerberos with NTLM fallback has been implemented for Windows and it works fine capturing the usernames while browsing internet. I am trying to do the samething for Linux/Mac OSs so that usersnames are captured in the logs. NTLM doesn't seem to be working
Trying to see what is the best way to authenticate users for Linux/MAC OS users for a limited time?? (Windows is already resolved)
Something like using a cookie. Sessions would be vaild for 3 hrs and then the users need to re-authenticate.