mjhjmtu

This is a question more for Android (feel free to move the question to the respective site) but it is mostly from the way Unix works.

I'm trying to do the reverse tethering to my Samsung J1 (Android 5.1.1) rooted in a PC with Debian Jessie connected to the internet through a proxy and I'm standing in (I think) in the last step. I comment what I have done so far:

On the phone:
Active Developer Options >> Active USB Debugging >> I am going to Anchorage to network and Portable and active zone Anchorage (sorry for the translation, I'm from Cuba) to USB network >> When I do this I open the Virtual Terminal emulator (an apk) and I access as root (su) and I check the network interfaces with ifconfig , which returns a "new" interface called rndis0 and with IP 192.168.42.129

On the PC with Debian:
I open the terminal and I access as root (only to not have to be putting sudo every time) >> ifconfig and it returns a "new" interface called usb0 with IP 192.168.42.111

I ping from the phone to the PC and vice versa and everything is ok (I get answers in the two sides), now it's time to give the phone a gateway, I do it from the same phone (the adb package commands do not work properly when I try to manage the phone networks) with the command:
route add default gw 192.168.42.111 dev rndis0 >> putting here the IP of the PC

At this point I am able to ping the google DNS (both by IP and by name) from the terminal emulator, but now I need to make the applications go through the proxy with my username and password.

Then the question would be: how to tell my Android phone that all the traffic of the applications (principally Whatsapp) go through the proxy (of which, obviously, I have the address, port, username and password)? Any illuminating idea?

Thanks

PS: No way of use WiFi here!!!