How to connect MTP devices via USB?

Install gmtp, and use it to connect to the phone or tablet :

sudo apt-get install gmtp

You just install jmtpfs (via sudo apt-get install jmtpfs). After connecting your phone via USB, enable the MTP file transfer on your phone and it will show up as USB device on your computer. You can then access the whole file system (and not only the pictures, as with PTP) of your Android device.

This worked for me with (K)Ubuntu 14.04 LTS and my Motorola Moto G.

Try the "AirDroid" App from Play Store. It allows you to use a browser based interface (on your computer) to transfer files from a Windows/Linux pc. Since it's browser based UI, no need to install anything on the pc side.