pptpd[]: GRE: read(fd=6,buffer=611860,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs

vzctl stop 101
vzctl set 101 --features ppp:on --save
vzctl start 101
vzctl set 101 --devices c:108:0:rw --save
vzctl exec 101 mknod /dev/ppp c 108 0
vzctl exec 101 chmod 600 /dev/ppp

modprobe tun
modprobe ppp-compress-18
modprobe ppp_mppe
modprobe ppp_deflate
modprobe ppp_async
modprobe pppoatm
modprobe ppp_generic