On startup, I have ethernet and a 3G modem connected to my raspberry pi. How do I set the pi so that it connects to the 3G modem instead of the ethernet? I am using raspbian.
I got it to work using wvdial, and by modifying a few files. In the rc.local file I used
sudo wvdial & to start the modem on startup. After, I used
ifdown --force eth0 and
ifup --force ppp0 to make sure the 3G modem was being used instead of the direct ethernet connection. In my /etc/network/interfaces file I added
iface ppp0 init wvdial. The result is that on startup the modem is used even if the ethernet is attached. As well, if the modem is removed, the ethernet is used, and if the modem is plugged back in, the 3G modem is used.