Flying Carpet is a cross platform application that will allow wireless, and encrypted, file transfers between different devices. No network infrastructure required (access point, router, switch).
You can use two computers (with Mac, Linux or even Windows) that have wireless connection (wireless chip) and are located nearby.
Don't have USB? Do not have access to a wireless network or do you have but do not trust it (is it public etc)?
Need to transfer a file larger than 2 GB between different systems, but do not want to create a network?
Try the app, it's free and you can download it from Github for the platform you are interested in.