我在 Fritzbox 上配置了 VPN 存取。現在我正在嘗試在 CentOS 6 電腦上設定 VPN 用戶端。為此，我已經安裝了 vpnc 和 NetworkManager-vpnc，並且按照以下說明進行操作http://tosit.de/aktuelles/vpn-verbindung-unter-ubuntu-zu-fritzbox.html
但每次當我嘗試連接 VPN（從命令列“vpnc”）時，我都會收到錯誤
vpnc: vpnc.c:1166: lifetime_ike_process: Assertion `0' failed.
另外，如果我嘗試使用啟用了偵錯輸出的網路管理器（nm-vpnc-service --debug），我會得到：
** Message: <info> vpnc started with pid 13161
vpnc: vpnc.c:1166: lifetime_ike_process: Assertion `0' failed.
** (process:13150): WARNING **: <WARN> vpnc_watch_cb(): vpnc died with signal 6
在 /var/log/message （客戶端）中我得到：
Dec 18 19:02:30 lifebook01 NetworkManager[12964]: <info> Starting VPN service 'org.freedesktop.NetworkManager.vpnc'...
Dec 18 19:02:30 lifebook01 NetworkManager[12964]: <info> VPN service 'org.freedesktop.NetworkManager.vpnc' started (org.freedesktop.NetworkManager.vpnc), PID 13282
Dec 18 19:02:30 lifebook01 NetworkManager[12964]: <info> VPN service 'org.freedesktop.NetworkManager.vpnc' appeared, activating connections
Dec 18 19:02:30 lifebook01 NetworkManager[12964]: <info> VPN plugin state changed: 1
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <info> VPN plugin state changed: 3
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <info> VPN connection 'Fritzbox test' (Connect) reply received.
Dec 18 19:02:35 lifebook01 kernel: tun0: Disabled Privacy Extensions
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <info> VPN plugin state changed: 6
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <info> VPN plugin state change reason: 0
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <warn> error disconnecting VPN: Could not process the request because no VPN connection was active.
Dec 18 19:02:35 lifebook01 NetworkManager[12964]: <info> Policy set 'System eth0' (eth0) as default for IPv4 routing and DNS.
有人知道這裡有什麼問題或我怎麼才能得到更好的錯誤訊息？