1，在CentOS6.3下用

/usr/sbin/pppd  pty "/usr/sbin/pptp publicip --nolaunchpppd" file /etc/ppp/options.pptp user user1 password password1
再用tail -f /var/log/messages看到log如下
Oct  8 03:25:41 localhost pppd[2057]: pppd 2.4.5 started by root, uid 0
Oct  8 03:25:41 localhost pppd[2057]: Using interface ppp0
Oct  8 03:25:41 localhost pppd[2057]: Connect: ppp0 <--> /dev/pts/2
Oct  8 03:25:41 localhost pptp[2058]: anon log[main:pptp.c:314]: The synchronous pptp option is NOT activated
Oct  8 03:25:41 localhost pptp[2066]: anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request'
Oct  8 03:25:41 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
Oct  8 03:25:41 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
Oct  8 03:25:42 localhost pptp[2066]: anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
Oct  8 03:25:42 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
Oct  8 03:25:42 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 19561).
Oct  8 03:25:45 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:950]: PPTP_SET_LINK_INFO received from peer_callid 0
Oct  8 03:25:45 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:953]:   send_accm is 00000000, recv_accm is FFFFFFFF
Oct  8 03:25:45 localhost pptp[2066]: anon warn[ctrlp_disp:pptp_ctrl.c:956]: Non-zero Async Control Character Maps are not supported!
Oct  8 03:25:45 localhost pppd[2057]: CHAP authentication succeeded
Oct  8 03:25:45 localhost pppd[2057]: LCP terminated by peer (tM-+)^R^@ Oct  8 03:25:45 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:950]: PPTP_SET_LINK_INFO received from peer_callid 0
Oct  8 03:25:45 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:953]:   send_accm is FFFFFFFF, recv_accm is FFFFFFFF
Oct  8 03:25:45 localhost pptp[2066]: anon warn[ctrlp_disp:pptp_ctrl.c:956]: Non-zero Async Control Character Maps are not supported!
Oct  8 03:25:45 localhost pptp[2066]: anon log[ctrlp_disp:pptp_ctrl.c:912]: Received Call Clear Request.
Oct  8 03:25:48 localhost pppd[2057]: Connection terminated.
Oct  8 03:25:48 localhost pppd[2057]: Modem hangup
Oct  8 03:25:48 localhost pptp[2058]: anon warn[decaps_hdlc:pptp_gre.c:204]: short read (-1): Input/output error
Oct  8 03:25:48 localhost pptp[2058]: anon warn[decaps_hdlc:pptp_gre.c:216]: pppd may have shutdown, see pppd log
Oct  8 03:25:48 localhost pptp[2066]: anon log[callmgr_main:pptp_callmgr.c:234]: Closing connection (unhandled)
Oct  8 03:25:48 localhost pptp[2066]: anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request'
Oct  8 03:25:48 localhost pptp[2066]: anon log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
Oct  8 03:25:48 localhost pppd[2057]: Exit.

2，google查资料得到修改下面这个文件
cat /etc/ppp/options
require-mppe
require-mppe-128
mppe-stateful
CentOS6.3中默认是lock，我把这个删除了，加上上面的内容，问题解决

3，重新拨号log信息如下
Oct 10 08:09:39 localhost kernel: PPP generic driver version 2.4.2
Oct 10 08:09:39 localhost pppd[2019]: pppd 2.4.5 started by root, uid 0
Oct 10 08:09:39 localhost pptp[2020]: anon log[main:pptp.c:314]: The synchronous pptp option is NOT activated
Oct 10 08:09:39 localhost pppd[2019]: Using interface ppp0
Oct 10 08:09:39 localhost pppd[2019]: Connect: ppp0 <--> /dev/pts/2
Oct 10 08:09:39 localhost pptp[2030]: anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request'
Oct 10 08:09:39 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
Oct 10 08:09:39 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
Oct 10 08:09:40 localhost pptp[2030]: anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
Oct 10 08:09:40 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
Oct 10 08:09:40 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 47065).
Oct 10 08:09:43 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:950]: PPTP_SET_LINK_INFO received from peer_callid 0
Oct 10 08:09:43 localhost pptp[2030]: anon log[ctrlp_disp:pptp_ctrl.c:953]:   send_accm is 00000000, recv_accm is FFFFFFFF
Oct 10 08:09:43 localhost pptp[2030]: anon warn[ctrlp_disp:pptp_ctrl.c:956]: Non-zero Async Control Character Maps are not supported!
Oct 10 08:09:43 localhost pppd[2019]: CHAP authentication succeeded
Oct 10 08:09:43 localhost kernel: PPP MPPE Compression module registered
Oct 10 08:09:43 localhost pppd[2019]: MPPE 128-bit stateless compression enabled
Oct 10 08:09:45 localhost pppd[2019]: local  IP address 10.0.0.4
Oct 10 08:09:45 localhost pppd[2019]: remote IP address 10.0.0.1



后来这个问题在Debian 6.0中同样出现了，用同样的方法解决