Issue:
Mar 20 19:05:00 ct pppd[1362]: LCP: timeout sending Config-Requests
Mar 20 19:05:00 ct pppd[1362]: Connection terminated.
Mar 20 19:05:00 ct pppd[1362]: Modem hangup
Mar 20 19:05:00 ct pptp[1363]: anon warn[decaps_hdlc:pptp_gre.c:217]: short read (-1): Input/output error
Mar 20 19:05:00 ct pptp[1363]: anon warn[decaps_hdlc:pptp_gre.c:229]: pppd may have shutdown, see pppd log
Mar 20 19:05:00 ct pptp[1376]: anon log[callmgr_main:pptp_callmgr.c:242]: Closing connection (unhandled)
Mar 20 19:05:00 ct pptp[1376]: anon log[ctrlp_rep:pptp_ctrl.c:254]: Sent control packet type is 12 'Call-Clear-Request'
Mar 20 19:05:00 ct pptp[1376]: anon log[call_callback:pptp_callmgr.c:81]: Closing connection (call state)
Resolution:
# modprobe nf_conntrack_proto_gre
# modprobe ip_gre
# modprobe nf_conntrack_pptp
