我使用的是 Ubuntu 14.04。我正在尝试使用bestfreevpn.com使用 PPTP 协议。之前我尝试过其他一些免费 VPN 服务，但似乎无法连接到任何服务。我不知道这里出了什么问题。这是我的/var/log/syslog转储。
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN service 'pptp' started (org.freedesktop.NetworkManager.pptp), PID 12761
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN service 'pptp' appeared; activating connections
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN plugin state changed: starting (3)
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN connection 'Free-VPN' (Connect) reply received.
Jan 31 22:40:15 crysoberil pppd[12765]: Plugin /usr/lib/pppd/2.4.5/nm-pptp-pppd-plugin.so loaded.
Jan 31 22:40:15 crysoberil pppd[12765]: pppd 2.4.5 started by root, uid 0
Jan 31 22:40:15 crysoberil pppd[12765]: Using interface ppp0
Jan 31 22:40:15 crysoberil pppd[12765]: Connect: ppp0 <--> /dev/pts/25
Jan 31 22:40:15 crysoberil NetworkManager[23756]: SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Jan 31 22:40:15 crysoberil NetworkManager[23756]: SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <warn> /sys/devices/virtual/net/ppp0: couldn't determine device driver; ignoring...
Jan 31 22:40:15 crysoberil pptp[12769]: nm-pptp-service-12761 log[main:pptp.c:314]: The synchronous pptp option is NOT activated
Jan 31 22:40:15 crysoberil pptp[12773]: nm-pptp-service-12761 warn[open_inetsock:pptp_callmgr.c:329]: connect: Connection refused
Jan 31 22:40:15 crysoberil pptp[12773]: nm-pptp-service-12761 fatal[callmgr_main:pptp_callmgr.c:127]: Could not open control connection to 192.254.236.51
Jan 31 22:40:15 crysoberil pptp[12769]: nm-pptp-service-12761 fatal[open_callmgr:pptp.c:487]: Call manager exited with error 256
Jan 31 22:40:15 crysoberil pppd[12765]: Modem hangup
Jan 31 22:40:15 crysoberil pppd[12765]: Connection terminated.
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <warn> VPN plugin failed: 1
Jan 31 22:40:15 crysoberil NetworkManager[23756]: SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Jan 31 22:40:15 crysoberil pppd[12765]: Exit.
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <warn> VPN plugin failed: 1
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <warn> VPN plugin failed: 1
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN plugin state changed: stopped (6)
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> VPN plugin state change reason: 0
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <info> Policy set 'crysoberil ' (wlan0) as default for IPv4 routing and DNS.
Jan 31 22:40:15 crysoberil NetworkManager[23756]: <warn> error disconnecting VPN: Could not process the request because no VPN connection was active.
Jan 31 22:40:21 crysoberil NetworkManager[23756]: <info> VPN service 'pptp' disappeared