hello everybudy,
i have tryed userppp, it works well and seems to be faster than kernel 
ppp (??), but i have a message when i connect :
PPp ON machine> Error: tun_configure: ioctl(SIOCSIFMTU): Operation not 
permitted. the connection runs and after five minutes, it writes :
ppp ON machine> Warning: deflink: unable to set physical to speed 0.

an idea ?

thanks.