Questions[pptp](ubuntu)

syslog error:

May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: LCP: timeout sending Config-Requests
May 8 09:54:21 pptpteste-VirtualBox NetworkManager[2367]: LCP: timeout sending Config-Requests
May 8 09:54:21 pptpteste-VirtualBox NetworkManager[2367]: Connection terminated.
May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: Connection terminated.
May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: Terminating on signal 15
May 8 09:54:21 pptpteste-VirtualBox pptp[2375]: nm-pptp-service-2351 warn[decaps_hdlc:pptp_gre.c:226]: short read (-1): Input/output error
May 8 09:54:21 pptpteste-VirtualBox pptp[2375]: nm-pptp-service-2351 warn[decaps_hdlc:pptp_gre.c:238]: pppd may have shutdown, see pppd log
May 8 09:54:21 pptpteste-VirtualBox pptp[2382]: nm-pptp-service-2351 log[callmgr_main:pptp_callmgr.c:245]: Closing connection (unhandled)
May 8 09:54:21 pptpteste-VirtualBox pptp[2382]: nm-pptp-service-2351 log[ctrlp_rep:pptp_ctrl.c:258]: Sent control packet type is 12 'Call-Clear-Request'
May 8 09:54:21 pptpteste-VirtualBox pptp[2382]: nm-pptp-service-2351 log[call_callback:pptp_callmgr.c:84]: Closing connection (call state)
May 8 09:54:21 pptpteste-VirtualBox NetworkManager[2367]: Terminating on signal 15
May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: Child process /sbin/pptp 150.161.70.99 --nolaunchpppd --loglevel 0 --logstring nm-pptp-service-2351 (pid 2370) terminated with signal 15
May 8 09:54:21 pptpteste-VirtualBox NetworkManager[2367]: Child process /sbin/pptp 150.161.70.99 --nolaunchpppd --loglevel 0 --logstring nm-pptp-service-2351 (pid 2370) terminated with signal 15
May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: Modem hangup
May 8 09:54:21 pptpteste-VirtualBox NetworkManager[2367]: Modem hangup
May 8 09:54:21 pptpteste-VirtualBox pppd[2367]: Exit.
May 8 09:54:22 pptpteste-VirtualBox NetworkManager[553]: <info> [1588942461.5657] vpn-connection[0x560f4da78590,9cfb61ed-0a2a-4e49-b47c-63ba8b5132b0,"CIN",0]: VPN service disappeared

I've just upgraded to 18.04, and I have a problem that my wife cannot connect to her work PPTP-based VPN through our home network (Linux box operates as router). If I bypass the linux box, the VPN connection connects fine.

I had trouble setting this up back in the day, until I found I needed load module nf_nat_pptp. After that, it worked fine until the upgrade. I've tried disabling UFW, but it still won't work.

I can't seem to get much debug information on this. (Any debug tips?) The only thread I've got on the problem is a RasSstp error in Windows with message, "A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider." Would the Linux box (as router) need to be aware of the certification authority to allow the route?! Or perhaps it's inserting its own certificate in the chain, and that isn't a trusted CA at the Windows server end?

I just don't know enough about the protocol to unwind this---any help would be greatly appreciated.

I am a network engineer having quite limited experience with Ubuntu. I have been following up these online instructions to set up a pptp server but without much luck to get it to work. My server is a vm running an Apple Xserve behind a Cisco firewall. I made sure tcp 1723 and GRE are opened for the box. Below is the syslog output, looks like I always got stuck at GRE: Bad checksum from pppd. I'm running Ubuntu 10.04.

Sep 24 13:21:53 ubuntu pptpd[1231]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Sep 24 13:21:53 ubuntu pptpd[1231]: CTRL: Reaping child PPP[1232]
Sep 24 13:21:53 ubuntu pptpd[1231]: CTRL: Client 166.137.85.165 control connection finished
Sep 24 13:22:41 ubuntu pptpd[1276]: MGR: connections limit (100) reached, extra IP addresses ignored
Sep 24 13:22:41 ubuntu pptpd[1277]: MGR: Manager process started
Sep 24 13:22:41 ubuntu pptpd[1277]: MGR: Maximum of 100 connections available
Sep 24 13:22:50 ubuntu pptpd[1278]: CTRL: Client 166.137.85.165 control connection started
Sep 24 13:22:51 ubuntu pptpd[1278]: CTRL: Starting call (launching pppd, opening GRE)
Sep 24 13:22:51 ubuntu pppd[1279]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
Sep 24 13:22:51 ubuntu pppd[1279]: pppd 2.4.5 started by root, uid 0
Sep 24 13:22:51 ubuntu pppd[1279]: Using interface ppp0
Sep 24 13:22:51 ubuntu pppd[1279]: Connect: ppp0 <--> /dev/pts/1
Sep 24 13:22:51 ubuntu pptpd[1278]: GRE: Bad checksum from pppd.
Sep 24 13:23:21 ubuntu pppd[1279]: LCP: timeout sending Config-Requests
Sep 24 13:23:21 ubuntu pppd[1279]: Connection terminated.
Sep 24 13:23:21 ubuntu pppd[1279]: Modem hangup
Sep 24 13:23:21 ubuntu pppd[1279]: Exit.
Sep 24 13:23:21 ubuntu pptpd[1278]: GRE: read(fd=6,buffer=805a540,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Sep 24 13:23:21 ubuntu pptpd[1278]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Sep 24 13:23:21 ubuntu pptpd[1278]: CTRL: Reaping child PPP[1279]
Sep 24 13:23:21 ubuntu pptpd[1278]: CTRL: Client 166.137.85.165 control connection finished

I will be setting up a VPN on my home server and in tutorials I've read it says that the protocol can only be used with passwords, not key-files. To me this doesn't seem very secure so I was wondering if it's possible to tunnel PPTP over SSH or something like that. Basically, how do you create a secure PPTP connection? Can you get VPN-like functionality just through SSH and use it instead of PPTP?

This is under Ubuntu 11.10

I have a script that starts a PPTP VPN connection fetches a couple of files, then closes the connection. When I run this script from a terminal prompt it works perfectly; however, when I schedule it to run with CRON the nmcli commands in the script generate errors. The VPN connections are configured to be used by any user, not just my account.

Here is the relevant line of the script:

/usr/bin/nmcli con up id MyVPN

And here is the errors that generate when using it in CRON:

** (process:6360): WARNING **: _nm_object_get_property: Error getting 'WirelessHardwareEnabled' for /org/freedesktop/NetworkManager: (9) Rejected send message, 2 matched rules; type="method_call", sender=":1.624" (uid=1000 pid=6360 comm="/usr/bin/nmcli con up id MyVPN ") interface="org.freedesktop.DBus.Properties" member="Get" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1029 comm="NetworkManager ") ** (process:6360): WARNING **:

_nm_object_get_property: Error getting 'WwanHardwareEnabled' for /org/freedesktop/NetworkManager: (9) Rejected send message, 2 matched rules; type="method_call", sender=":1.624" (uid=1000 pid=6360 comm="/usr/bin/nmcli con up id MyVPN ") interface="org.freedesktop.DBus.Properties" member="Get" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1029 comm="NetworkManager ") ** (process:6360): WARNING **:

_nm_object_get_property: Error getting 'WimaxHardwareEnabled' for /org/freedesktop/NetworkManager: (9) Rejected send message, 2 matched rules; type="method_call", sender=":1.624" (uid=1000 pid=6360 comm="/usr/bin/nmcli con up id MyVPN ") interface="org.freedesktop.DBus.Properties" member="Get" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1029 comm="NetworkManager ") ** (process:6360): WARNING **:

_nm_object_get_property: Error getting 'State' for /org/freedesktop/NetworkManager: (9) Rejected send message, 2 matched rules; type="method_call", sender=":1.624" (uid=1000 pid=6360 comm="/usr/bin/nmcli con up id MyVPN ") interface="org.freedesktop.DBus.Properties" member="Get" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1029 comm="NetworkManager ")

Any ideas would be appreciated!