我的 VPN 連線在全新安裝的 Kubuntu 15.04 上不起作用，而在 14.10 及更早版本上卻如此。我可以透過「連接編輯器」建立連接，但是當我想連接時，它會閃爍一個窗口，我可能應該在其中輸入密碼（但它立即消失，所以我無法判斷）。說了一會兒正在連線後就放棄了。系統日誌如下圖所示：
grep NetworkManager /var/log/syslog
Jul 9 15:12:11 hostname NetworkManager[811]: <info> Starting VPN service 'vpnc'...
Jul 9 15:12:11 hostname NetworkManager[811]: <info> VPN service 'vpnc' started (org.freedesktop.NetworkManager.vpnc), PID 2136
Jul 9 15:12:11 hostname NetworkManager[811]: <info> VPN service 'vpnc' appeared; activating connections
Jul 9 15:12:15 hostname ureadahead[307]: ureadahead:NetworkManager_new.1445: Ignored relative path
Jul 9 15:12:15 hostname ureadahead[307]: ureadahead:NetworkManager: Ignored relative path
Jul 9 15:12:15 hostname ureadahead[307]: message repeated 3 times: [ ureadahead:NetworkManager: Ignored relative path]
Jul 9 15:12:15 hostname ureadahead[307]: ureadahead:NetworkManager_new.1490: Ignored relative path
Jul 9 15:12:15 hostname ureadahead[307]: ureadahead:NetworkManager: Ignored relative path
Jul 9 15:12:15 hostname ureadahead[307]: message repeated 2 times: [ ureadahead:NetworkManager: Ignored relative path]
Jul 9 15:14:11 hostname NetworkManager[811]: <error> [1436447651.584396] [vpn-manager/nm-vpn-connection.c:1778] get_secrets_cb(): Failed to request VPN secrets #2: (6) No agents were available for this request.
使用設定中的密碼建立連線也沒有幫助： Jul 9 16:46:17 hostname NetworkManager[811]: [1436453177.020663] [vpn-manager/nm-vpn-connection.c:1778] get_secrets_cb(): 無法要求機密#2：(6) 沒有代理可用於此請求。
我嘗試過手動創建一個conf文件，這似乎部分成功。ifconfig有一個名為 的額外項目tun0，我可以使用 URL ping 網站，但無法在瀏覽器中載入任何網站。這可能表明我的問題類似於這個，但也不完全是，因為網站無法運作是一個很大的限制。這就是我在那裡所做的：
user@hostname:~$ sudo vpnc-connect /etc/vpnc/my_vpn_config.conf
[sudo] password for user:
Enter IPSec secret for [email protected]:
Enter password for [email protected]:
VPNC started in background (pid: 19663)...
user@hostname:~$ ping askubuntu.com
PING askubuntu.com (122.122.122.122) 56(84) bytes of data.
64 bytes from 122.122.122.122: icmp_seq=1 ttl=59 time=51.1 ms
user@hostname:~$ sudo vpnc-disconnect
Terminating vpnc daemon (pid: 19663)
此連線的系統日誌如下所示：
Jul 9 16:15:54 hostname NetworkManager[811]: nm_device_get_device_type: assertion 'NM_IS_DEVICE (self)' failed
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): carrier is OFF
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): new Tun device (driver: 'unknown' ifindex: 6)
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): exported as /org/freedesktop/NetworkManager/Devices/5
Jul 9 16:15:54 hostname NetworkManager[811]: <info> devices added (path: /sys/devices/virtual/net/tun0, iface: tun0)
Jul 9 16:15:54 hostname NetworkManager[811]: <info> device added (path: /sys/devices/virtual/net/tun0, iface: tun0): no ifupdown configuration found.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): link connected
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: unmanaged -> unavailable (reason 'connection-assumed') [10 20 41]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: unavailable -> disconnected (reason 'connection-assumed') [20 30 41]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) starting connection 'tun0'
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 1 of 5 (Device Prepare) scheduled...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 1 of 5 (Device Prepare) started...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 2 of 5 (Device Configure) scheduled...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 1 of 5 (Device Prepare) complete.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 2 of 5 (Device Configure) starting...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: prepare -> config (reason 'none') [40 50 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 2 of 5 (Device Configure) successful.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 3 of 5 (IP Configure Start) scheduled.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 2 of 5 (Device Configure) complete.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 3 of 5 (IP Configure Start) started...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: config -> ip-config (reason 'none') [50 70 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 5 of 5 (IPv4 Configure Commit) scheduled...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 3 of 5 (IP Configure Start) complete.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 5 of 5 (IPv4 Commit) started...
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: ip-config -> ip-check (reason 'none') [70 80 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) Stage 5 of 5 (IPv4 Commit) complete.
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: ip-check -> secondaries (reason 'none') [80 90 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> (tun0): device state change: secondaries -> activated (reason 'none') [90 100 0]
Jul 9 16:15:54 hostname NetworkManager[811]: <info> Activation (tun0) successful, device activated.
Jul 9 16:17:49 hostname NetworkManager[811]: <info> (tun0): device state change: activated -> unmanaged (reason 'removed') [100 10 36]
Jul 9 16:17:49 hostname NetworkManager[811]: <info> (tun0): deactivating device (reason 'removed') [36]
Jul 9 16:17:49 hostname NetworkManager[811]: <info> devices removed (path: /sys/devices/virtual/net/tun0, iface: tun0)
kvpncerror: Timeout while connecting to 123.123.123.123. vpnc connect process will be killed.Ping 閘道會在 50 毫秒內回傳。
我不太確定還可以嘗試什麼。其他選項（pptp、openconnect、openvpn）似乎需要 CA 證書，但我沒有，所以我認為我只能使用 vpnc。希望有人能有一些想法嗎？
編輯：它似乎是一個變體這個錯誤，儘管那裡的修復對我沒效。