错误日志
Sep 21 10:16:23 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN service 'pptp' disappeared
Sep 21 10:17:01 hehongwei-ThinkPad-T410 CRON[4142]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Sep 21 10:18:00 hehongwei-ThinkPad-T410 wpa_supplicant[1009]: wlan0: CTRL-EVENT-SCAN-STARTED
Sep 21 10:18:06 hehongwei-ThinkPad-T410 wpa_supplicant[1009]: nl80211: send_and_recv->nl_recvmsgs failed: -33
Sep 21 10:20:00 hehongwei-ThinkPad-T410 wpa_supplicant[1009]: wlan0: CTRL-EVENT-SCAN-STARTED
Sep 21 10:20:06 hehongwei-ThinkPad-T410 wpa_supplicant[1009]: nl80211: send_and_recv->nl_recvmsgs failed: -33
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: Starting VPN service 'pptp'...
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN service 'pptp' started (org.freedesktop.NetworkManager.pptp), PID 4207
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN service 'pptp' appeared; activating connections
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN plugin state changed: starting (3)
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN connection 'VPN 连接' (Connect) reply received.
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: VPN connection 'VPN 连接' failed to connect: '无效的网关“gateway”'.
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: Policy set 'btchina' (wlan0) as default for IPv4 routing and DNS.
Sep 21 10:21:17 hehongwei-ThinkPad-T410 NetworkManager[815]: error disconnecting VPN: Could not process the request because no VPN connection was active.

ubuntu菜鸟，大神请指点