vpnc工作但network-manager-vpnc失败

我正在尝试连接到vpnc vpn。

我首先创建了一个conf文件/etc/vpnc/clientvpn.conf如下所示：

 ## generated by pcf2vpnc IPSec ID mygroupid IPSec gateway some.ip.add.ress IPSec secret mygrouppassword Xauth username myusername Xauth password myuserpassword IKE Authmode psk 

并使用sudo vpnc clientvpn工作正常。

现在我想使用network-manager vpnc插件。 我创建了一个新的vpn设置，并设置了不同的值：

我将高级设置保留为默认值。 尝试从NetworkManager连接失败，并显示以下日志：

 NetworkManager[1155]:  Starting VPN service 'vpnc'... NetworkManager[1155]:  VPN service 'vpnc' started (org.freedesktop.NetworkManager.vpnc), PID 5888 NetworkManager[1155]:  VPN service 'vpnc' appeared; activating connections NetworkManager[1155]:  VPN plugin state changed: starting (3) NetworkManager[1155]:  VPN connection 'clientvpn' (Connect) reply received. NetworkManager[1155]: SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/tun0, iface: tun0) NetworkManager[1155]: SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/tun0, iface: tun0): no ifupdown configuration found. NetworkManager[1155]:  /sys/devices/virtual/net/tun0: couldn't determine device driver; ignoring... NetworkManager[1155]: SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/tun0, iface: tun0) NetworkManager[1155]:  VPN plugin failed: 1 NetworkManager[1155]:  VPN plugin state changed: stopped (6) NetworkManager[1155]:  VPN plugin state change reason: 0 NetworkManager[1155]:  Policy set 'Connexion filaire 1' (eth0) as default for IPv4 routing and DNS. NetworkManager[1155]:  error disconnecting VPN: Could not process the request because no VPN connection was active. 

我不确定/sys/devices/virtual/net/tun0: couldn't determine device driver; ignoring... /sys/devices/virtual/net/tun0: couldn't determine device driver; ignoring...是一条有意义的信息。

为什么nm插件失败，而vpnc工作正常？