PPTP MAC断线问题

Posted by Vincent on August 1, 2016

MAC连接pptp服务经常断线

日志内容如下

Aug  1 14:01:06 s1 pptpd[21666]: CTRL: Client 218.88.x.155 control connection finished
Aug  1 14:05:34 s1 pptpd[21965]: CTRL: Client 218.88.x.155 control connection started
Aug  1 14:05:34 s1 pptpd[21965]: CTRL: Starting call (launching pppd, opening GRE)
Aug  1 14:05:34 s1 pppd[21967]: Warning: can't open options file /home/xxxx/.ppprc: Permission denied
Aug  1 14:05:34 s1 pppd[21967]: Plugin /usr/lib64/pptpd/pptpd-logwtmp.so loaded.
Aug  1 14:05:34 s1 pppd[21967]: pptpd-logwtmp: $Version$
Aug  1 14:05:34 s1 pppd[21967]: Using interface ppp0
Aug  1 14:05:34 s1 pppd[21967]: Connect: ppp0 <--> /dev/pts/2
Aug  1 14:05:34 s1 pptpd[21965]: GRE: Bad checksum from pppd.
Aug  1 14:05:38 s1 pppd[21967]: MPPE 128-bit stateless compression enabled
Aug  1 14:05:41 s1 pppd[21967]: Unsupported protocol 'Apple Client Server Protocol Control' (0x8235) received
Aug  1 14:05:41 s1 pppd[21967]: Unsupported protocol 'IPv6 Control Protocol' (0x8057) received
Aug  1 14:05:41 s1 pppd[21967]: Unsupported protocol 'Apple Client Server Protocol Control' (0x8235) received
Aug  1 14:05:41 s1 pppd[21967]: Cannot determine ethernet address for proxy ARP
Aug  1 14:05:41 s1 pppd[21967]: local  IP address 192.168.x.1
Aug  1 14:05:41 s1 pppd[21967]: remote IP address 192.168.x.10
Aug  1 14:05:41 s1 pppd[21967]: pptpd-logwtmp.so ip-up ppp0 xxxxx 218.88.20.155
Aug  1 14:05:43 s1 pptpd[21965]: GRE: read(fd=7,buffer=6097c0,len=8260) from network failed: status = -1 error = Message too long
Aug  1 14:05:43 s1 pptpd[21965]: CTRL: GRE read or PTY write failed (gre,pty)=(7,6)
Aug  1 14:05:43 s1 pppd[21967]: Modem hangup
Aug  1 14:05:43 s1 pppd[21967]: pptpd-logwtmp.so ip-down ppp0
Aug  1 14:05:43 s1 pppd[21967]: Connect time 0.1 minutes.
Aug  1 14:05:43 s1 pppd[21967]: Sent 9063 bytes, received 3553 bytes.
Aug  1 14:05:43 s1 pppd[21967]: MPPE disabled
Aug  1 14:05:43 s1 pppd[21967]: Connection terminated.
Aug  1 14:05:43 s1 pppd[21967]: Exit.
Aug  1 14:05:43 s1 pptpd[21965]: CTRL: Client 218.88.20.155 control connection finished

主要错误是这句

GRE: read(fd=7,buffer=6097c0,len=8260) from network failed: status = -1

GRE 通用路由封装(英语:Generic Routing Encapsulation,缩写为GRE),一种隧道协议,可以在虚拟点对点链路中封装多种网络层协议。由思科系统开发,在RFC 2784中定义。Wiki

MTU最大传输单元(英语:Maximum Transmission Unit,缩写MTU)是指一种通信协议的某一层上面所能通过的最大数据包大小(以字节为单位)wiki

如果超出MTU设置的值数据包可能会被分段传输.然后又可能会造成这个错误.

尝试调整MTU设置 . 因为Windows的默认值是 1472 .因此将MAC的设置成1472.目前连接比较稳定.

MAC MTU设置

MAC set MTU

连接L2TP协议的vpn, 填好信息报错“IPSec 共享密钥”丢失

/etc/ppp 目录下创建一个 options目录

内容如下

plugin L2TP.ppp
l2tpnoipsec