Thread: pptpd not responding when connecting

i have been trying set vpn services on ubuntu 11.10 server. according every tutorial have found, have set correctly, every time try connect (over wan or lan) says server did not respond. thing have been able find haven't done has been suggested enable gre protocol 47 on firewall, firewall disabled (both on server , router). vpn passthrough enabled on router , port 1723 forwarded through router. other network services work (ssh, vnc, etc...) can't connect vpn. ideas?

i seem have made progress. have been able connect intermittently, though cannot access of machines on vpn while connected. here output /var/log/syslog:

jan 9 14:20:11 tom-server pptpd[2245]: ctrl: client xxx.xxx.xxx.xxx control connection started
jan 9 14:20:11 tom-server pptpd[2245]: ctrl: starting call (launching pppd, opening gre)
jan 9 14:20:11 tom-server pppd[2246]: plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
jan 9 14:20:11 tom-server pppd[2246]: pppd 2.4.5 started root, uid 0
jan 9 14:20:11 tom-server pppd[2246]: using interface ppp0
jan 9 14:20:11 tom-server pppd[2246]: connect: ppp0 <--> /dev/pts/0
jan 9 14:20:11 tom-server pptpd[2245]: gre: bad checksum pppd.
jan 9 14:20:11 tom-server networkmanager[1090]: scplugin-ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
jan 9 14:20:11 tom-server networkmanager[1090]: scplugin-ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
jan 9 14:20:41 tom-server pppd[2246]: lcp: timeout sending config-requests
jan 9 14:20:41 tom-server pppd[2246]: connection terminated.
jan 9 14:20:41 tom-server networkmanager[1090]: scplugin-ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
jan 9 14:20:41 tom-server pppd[2246]: modem hangup
jan 9 14:20:41 tom-server pppd[2246]: exit.
jan 9 14:20:41 tom-server pptpd[2245]: gre: read(fd=6,buffer=6075a0,len=8196) pty failed: status = -1 error = input/output error, caused unexpected termination of pppd, check option syntax , pppd logs
jan 9 14:20:41 tom-server pptpd[2245]: ctrl: pty read or gre write failed (pty,gre)=(6,7)
jan 9 14:20:41 tom-server pptpd[2245]: ctrl: reaping child ppp[2246]
jan 9 14:20:41 tom-server pptpd[2245]: ctrl: client xxx.xxx.xxx.xxx control connection finished

i'm hoping out there have suggestion driving me nuts...

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