用sudo ppoeconf配置，但到后来还是上不去
错误显示为：
May 26 10:30:28 Flystutio pppd[6382]: Connect: ppp0 <--> eth0
May 26 10:30:31 Flystutio pppd[6382]: PAP authentication failed
May 26 10:30:31 Flystutio pppd[6382]: Connection terminated.
May 26 10:30:36 Flystutio pppd[6415]: Plugin rp-pppoe.so loaded.
May 26 10:30:36 Flystutio pppd[6417]: pppd 2.4.4 started by root, uid 0
May 26 10:30:36 Flystutio pppd[6417]: PPP session is 755
May 26 10:30:36 Flystutio pppd[6417]: Using interface ppp0
May 26 10:30:36 Flystutio pppd[6417]: Connect: ppp0 <--> eth0
May 26 10:30:39 Flystutio pppd[6417]: PAP authentication failed
May 26 10:30:39 Flystutio pppd[6417]: Connection terminated.
