最近我一直无法连接到 Cisco VPN 网关，vpnc即使我一直在使用vpnc连接到同一网关大约一年导致这次损坏......我使用的是命令行客户端，而不是 NetworkManager。
奇怪的是，有时如果我重新启动并再次尝试它会起作用......但是，今晚我尝试了几次并且从未通过......
我在 中看到以下消息/var/log/syslog：
Aug 21 22:44:56 sonbuntu NetworkManager[1193]: SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/tun0, iface: tun0)
Aug 21 22:44:56 sonbuntu NetworkManager[1193]: SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/tun0, iface: tun0): no ifupdown configuration found.
Aug 21 22:44:56 sonbuntu NetworkManager[1193]: <warn> /sys/devices/virtual/net/tun0: couldn't determine device driver; ignoring...
Aug 21 22:47:06 sonbuntu avahi-daemon[1116]: Withdrawing workstation service for tun0.
Aug 21 22:47:06 sonbuntu NetworkManager[1193]: SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/tun0, iface: tun0)
Aug 21 22:48:08 sonbuntu …