Entonces, el problema es básicamente que cualquier intento de conectarme a la VPN de mi oficina falla en Ubuntu 14.04.
No hay configuraciones especiales, pero vale la pena mencionar que es PPTP.
Puedo hacer ping al servidor con bastante facilidad. No estoy seguro de qué tipo de información puedo publicar aquí para que esto sea más diagnosticable, pero hágamelo saber.
El resultado es el siguiente:
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> Starting VPN service 'pptp'...
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> VPN service 'pptp' started (org.freedesktop.NetworkManager.pptp), PID 18760
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> VPN service 'pptp' appeared; activating connections
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> VPN plugin state changed: init (1)
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> VPN plugin state changed: starting (3)
Sep 29 17:24:27 pedri-home pppd[18764]: Plugin /usr/lib/pppd/2.4.5/nm-pptp-pppd-plugin.so loaded.
Sep 29 17:24:27 pedri-home NetworkManager[912]: <info> VPN connection 'Test2' (Connect) reply received.
Sep 29 17:24:27 pedri-home pppd[18764]: pppd 2.4.5 started by root, uid 0
Sep 29 17:24:27 pedri-home pppd[18764]: Using interface ppp0
Sep 29 17:24:27 pedri-home pppd[18764]: Connect: ppp0 <--> /dev/pts/26
Sep 29 17:24:27 pedri-home pptp[18767]: nm-pptp-service-18760 log[main:pptp.c:314]: The synchronous pptp option is NOT activated
Sep 29 17:24:27 pedri-home NetworkManager[912]: SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Sep 29 17:24:27 pedri-home NetworkManager[912]: SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
Sep 29 17:24:27 pedri-home NetworkManager[912]: <warn> /sys/devices/virtual/net/ppp0: couldn't determine device driver; ignoring...
Sep 29 17:24:28 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request'
Sep 29 17:24:29 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
Sep 29 17:24:29 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
Sep 29 17:24:29 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
Sep 29 17:24:29 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
Sep 29 17:24:29 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 150).
Sep 29 17:24:58 pedri-home pppd[18764]: LCP: timeout sending Config-Requests
Sep 29 17:24:58 pedri-home pppd[18764]: Connection terminated.
Sep 29 17:24:58 pedri-home NetworkManager[912]: <warn> VPN plugin failed: 1
Sep 29 17:24:58 pedri-home pppd[18764]: Modem hangup
Sep 29 17:24:58 pedri-home pptp[18767]: nm-pptp-service-18760 warn[decaps_hdlc:pptp_gre.c:204]: short read (-1): Input/output error
Sep 29 17:24:58 pedri-home pptp[18767]: nm-pptp-service-18760 warn[decaps_hdlc:pptp_gre.c:216]: pppd may have shutdown, see pppd log
Sep 29 17:24:58 pedri-home pppd[18764]: Exit.
Sep 29 17:24:58 pedri-home NetworkManager[912]: message repeated 2 times: [ <warn> VPN plugin failed: 1]
Sep 29 17:24:58 pedri-home NetworkManager[912]: <info> VPN plugin state changed: stopped (6)
Sep 29 17:24:58 pedri-home NetworkManager[912]: <info> VPN plugin state change reason: 0
Sep 29 17:24:58 pedri-home NetworkManager[912]: <info> Policy set 'Wired connection 1' (eth0) as default for IPv4 routing and DNS.
Sep 29 17:24:58 pedri-home pptp[18780]: nm-pptp-service-18760 log[callmgr_main:pptp_callmgr.c:234]: Closing connection (unhandled)
Sep 29 17:24:58 pedri-home pptp[18780]: nm-pptp-service-18760 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request'
Sep 29 17:24:58 pedri-home pptp[18780]: nm-pptp-service-18760 log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
Sep 29 17:24:58 pedri-home NetworkManager[912]: <warn> error disconnecting VPN: Could not process the request because no VPN connection was active.
Sep 29 17:24:58 pedri-home NetworkManager[912]: SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Sep 29 17:25:03 pedri-home NetworkManager[912]: <info> VPN service 'pptp' disappeared
Respuesta1
Tuve problemas similares al intentar configurar una VPN a través de la conexión ADSL de mi casa. Una cosa con la que tuve cierto éxito fue cambiar la MTU en la conexión PPPoE a Manual y configurarla en 1432. Todavía cae aleatoriamente de vez en cuando, pero se mantiene el tiempo suficiente para hacer algo de trabajo...