网络问题，用命令查看连接上了，可就是上不了网求助

用命令查看连接上了，可就是上不了网
fangjcc@ :~$ sudo pppoeconf
[sudo] password for fangjcc:
Plugin rp-pppoe.so loaded.poe.so loaded.
RP-PPPoE plugin version 3.8p compiled against pppd 2.4.5
fangjcc@:~$ sudo pppoeconf
/usr/sbin/pppoeconf: 521: modconf: not found
Plugin rp-pppoe.so loaded.
RP-PPPoE plugin version 3.8p compiled against pppd 2.4.5
fangjcc@ubuntu:~$ plog
Aug 11 07:23:43 ubuntu pppd[4193]: local IP address 115.56.2.178
Aug 11 07:23:43 ubuntu pppd[4193]: remote IP address 115.56.0.1
Aug 11 07:23:43 ubuntu pppd[4193]: primary DNS address 202.102.224.68
Aug 11 07:23:43 ubuntu pppd[4193]: secondary DNS address 202.102.227.68
Aug 11 07:25:59 ubuntu pppd[3777]: No response to 4 echo-requests
Aug 11 07:25:59 ubuntu pppd[3777]: Serial link appears to be disconnected.
Aug 11 07:25:59 ubuntu pppd[3777]: Connect time 9.0 minutes.
Aug 11 07:25:59 ubuntu pppd[3777]: Sent 40 bytes, received 40 bytes.
Aug 11 07:26:05 ubuntu pppd[3777]: Connection terminated.
Aug 11 07:26:05 ubuntu pppd[3777]: Modem hangup
fangjcc@ubuntu:~$ ifconfig ppp0
ppp0 Link encap:Point-to-Point Protocol
inet addr:123.14.231.153 P-t-P:123.14.224.1 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
RX packets:168 errors:0 dropped:0 overruns:0 frame:0
TX packets:101 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:16444 (16.4 KB) TX bytes:6820 (6.8 KB)[/size]