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I set up a PPTP VPN server (insecure, I know, but this effort is primarily a learning experience) using PPTPD on a spare Ubuntu 15.10 desktop I had laying around, but am unable to connect to it from Linux or Windows. When I attempt to connect from an Antergos machine, I get the following output from Network Manager:

Mar 15 10:21:14 mblasco-XPS NetworkManager[377]: <info>  Starting VPN service 'pptp'...
Mar 15 10:21:14 mblasco-XPS NetworkManager[377]: <info>  VPN service 'pptp' started (org.freedesktop.NetworkManager.pptp), PID 2903
Mar 15 10:21:14 mblasco-XPS NetworkManager[377]: <info>  VPN service 'pptp' appeared; activating connections
Mar 15 10:21:14 mblasco-XPS NetworkManager[377]: <info>  VPN plugin state changed: init (1)
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: <info>  VPN connection 'HawkHouse' (ConnectInteractive) reply received.
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: <info>  VPN plugin state changed: starting (3)
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: ** Message: pppd started with pid 2910
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: <info>  VPN connection 'HawkHouse' (Connect) reply received.
Mar 15 10:21:15 mblasco-XPS pppd[2910]: Plugin /usr/lib/pppd/2.4.7/nm-pptp-pppd-plugin.so loaded.
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: Plugin /usr/lib/pppd/2.4.7/nm-pptp-pppd-plugin.so loaded.
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (plugin_init): initializing
Mar 15 10:21:15 mblasco-XPS pppd[2910]: pppd 2.4.7 started by root, uid 0
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 3 / phase 'serial connection'
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: <info>  (ppp0): new Generic device (carrier: UNKNOWN, driver: 'unknown', ifindex: 16)
Mar 15 10:21:15 mblasco-XPS pppd[2910]: Using interface ppp0
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: Using interface ppp0
Mar 15 10:21:15 mblasco-XPS pppd[2910]: Connect: ppp0 <--> /dev/pts/1
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: Connect: ppp0 <--> /dev/pts/1
Mar 15 10:21:15 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 5 / phase 'establish'
Mar 15 10:21:15 mblasco-XPS pptp[2912]: nm-pptp-service-2903 log[main:pptp.c:333]: The synchronous pptp option is NOT activated
Mar 15 10:21:15 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_rep:pptp_ctrl.c:258]: Sent control packet type is 1 'Start-Control-Connection-Request'
Mar 15 10:21:15 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_disp:pptp_ctrl.c:758]: Received Start Control Connection Reply
Mar 15 10:21:15 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_disp:pptp_ctrl.c:792]: Client connection established.
Mar 15 10:21:16 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_rep:pptp_ctrl.c:258]: Sent control packet type is 7 'Outgoing-Call-Request'
Mar 15 10:21:16 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_disp:pptp_ctrl.c:877]: Received Outgoing Call Reply.
Mar 15 10:21:16 mblasco-XPS pptp[2922]: nm-pptp-service-2903 log[ctrlp_disp:pptp_ctrl.c:916]: Outgoing call established (call ID 0, peer's call ID 11).
Mar 15 10:21:16 mblasco-XPS pppd[2910]: Modem hangup
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: Modem hangup
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 11 / phase 'disconnect'
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: Connection terminated.
Mar 15 10:21:16 mblasco-XPS pppd[2910]: Connection terminated.
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <warn>  (ppp0): failed to disable userspace IPv6LL address handling
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <warn>  VPN plugin failed: connect-failed (1)
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 1 / phase 'dead'
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: ** Message: nm-pptp-ppp-plugin: (nm_exit_notify): cleaning up
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: ** (nm-pptp-service:2903): WARNING **: pppd exited with error code 16
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <warn>  VPN plugin failed: connect-failed (1)
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <warn>  VPN plugin failed: connect-failed (1)
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <info>  VPN plugin state changed: stopped (6)
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <info>  VPN plugin state change reason: unknown (0)
Mar 15 10:21:16 mblasco-XPS NetworkManager[377]: <warn>  error disconnecting VPN: Could not process the request because no VPN connection was active.

I had this working with the same configuration on an Antergos machine previously, but I cannot seem to get it working under Ubuntu.

I have my router configured to forward port 1723 to the Ubuntu desktop, and it appears from the connection log above that it does make it through and begins communicating with the server, but then drops the connection.

Below are the iptables rules present on the Ubuntu server hosting the VPN:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     gre  --  anywhere             anywhere            
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:1723 state NEW

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
TCPMSS     tcp  --  192.168.1.0/24       anywhere             tcp flags:SYN,RST/SYN TCPMSS clamp to PMTU
ACCEPT     gre  --  anywhere             anywhere            

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Any insight? Thanks in advance!

  • Where is VPN server (ubuntu/windows)? And what software are you using for VPN server? – ALex_hha Mar 15 '16 at 17:17
  • Server is running pptpd on Ubuntu 15.10 – mblasco Mar 15 '16 at 17:18
3

At least doesn't work just out from the box on Ubuntu 15.04

Mar 15 22:02:24 ubuntu1504 pptpd[5517]: /usr/sbin/pppd: Plugin /usr/lib/pptpd/pptpd-logwtmp.so is for pppd version 2.4.5, this is 2.4.6
Mar 15 22:02:24 ubuntu1504 pppd[5524]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so is for pppd version 2.4.5, this is 2.4.6
Mar 15 22:02:24 ubuntu1504 pptpd[5523]: GRE: read(fd=6,buffer=55c41d7ed4a0,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Mar 15 22:02:24 ubuntu1504 pptpd[5523]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Mar 15 22:02:24 ubuntu1504 pptpd[5523]: CTRL: Reaping child PPP[5524]
Mar 15 22:02:24 ubuntu1504 pptpd[5523]: CTRL: Client 192.168.1.7 control connection finished
Mar 15 22:02:24 ubuntu1504 pptpd[5523]: CTRL: Exiting now

Perhaps you should comment line logwtmp in /etc/pptpd.conf and restart the service.

# systemctl restart pptpd

Log from VPN server

Mar 15 22:08:05 ubuntu1504 pptpd[5650]: MGR: Manager process started
Mar 15 22:08:05 ubuntu1504 pptpd[5650]: MGR: Maximum of 41 connections available
Mar 15 22:08:11 ubuntu1504 pptpd[5652]: CTRL: Client 192.168.1.7 control connection started
Mar 15 22:08:11 ubuntu1504 pptpd[5652]: CTRL: Starting call (launching pppd, opening GRE)
Mar 15 22:08:11 ubuntu1504 pppd[5653]: pppd 2.4.6 started by root, uid 0
Mar 15 22:08:11 ubuntu1504 pppd[5653]: Using interface ppp0
Mar 15 22:08:11 ubuntu1504 pppd[5653]: Connect: ppp0 <--> /dev/pts/0
Mar 15 22:08:11 ubuntu1504 systemd[1]: Started ifup for ppp0.
Mar 15 22:08:11 ubuntu1504 systemd[1]: Starting ifup for ppp0...
Mar 15 22:08:11 ubuntu1504 sh[5657]: Unknown interface ppp0
Mar 15 22:08:14 ubuntu1504 pppd[5653]: peer from calling number 192.168.1.7 authorized
Mar 15 22:08:14 ubuntu1504 pppd[5653]: MPPE 128-bit stateless compression enabled
Mar 15 22:08:15 ubuntu1504 pppd[5653]: Cannot determine ethernet address for proxy ARP
Mar 15 22:08:15 ubuntu1504 pppd[5653]: local  IP address 192.168.100.1
Mar 15 22:08:15 ubuntu1504 pppd[5653]: remote IP address 192.168.100.200

After this modification I can successfully connect to the server from windows 7 box

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