If I were connected by wifi in my network, there isn't any problem because with AirDroid I can access the sdcard files using the browser.

However when I am out, how can I transfer a file from my phone to my PC? I can access my PC using SSH, but then from the PC I can't access the phone for get file using SCP.

I guess the question is: Is there any app that allow do such action? I think the only possible thing is install a SSH server in the phone, isn't it?