[muziling]

I use old pppd file in last nand version and add some files which store user/pwd under /etc/ppp directory, files are pap-secrets,chap-secrets,options.smd,options.smd1, this can let data connection work

Now I am search for new pppd connection method, so I found AT command which can obtain auth user/pwd
In fact, native android use rmnet, not pppd,