In your Woobox Landing Page campaign, you can restrict entry to “Once per Facebook user” or “Once per Facebook user per day”. While Facebook does not allow the automatic collection of data from its users, this entry restriction will require that the entrant is logged into a valid Facebook profile. Since Facebook is strict on fake/fraudulent profiles, this is a more secure way to restrict your campaign.
In the Settings tab of your campaign under Participant Limits, turn on entry restrictions, and then choose one of the Facebook restriction option:
In the Social -> Facebook Comment Picker section of your dashboard, you can also sync and randomly pick winners from comments on your Facebook posts (as well as export that comment data).