关于Ubuntu的VNC应用

最近在配置VPN，先配置比较容易的xl2tpd的VPN。没加IPSEC，就是单独的xl2tpd的连接。配置也都是照网上配的。可是在最后echo 'c zhy' > /var/run/xl2tpd/l2tp-control 的时候，总是感觉成功一下，断一下。

服务器端用xl2tpd -D获得的日志是这样的：

xl2tpd[3283]: pppd 4495 successfully terminated
xl2tpd[3283]: start_pppd: I'm running:
xl2tpd[3283]: "/usr/sbin/pppd"
xl2tpd[3283]: "passive"
xl2tpd[3283]: "nodetach"
xl2tpd[3283]: "192.168.191.1:192.168.191.2"
xl2tpd[3283]: "refuse-pap"
xl2tpd[3283]: "auth"
xl2tpd[3283]: "require-chap"
xl2tpd[3283]: "name"
xl2tpd[3283]: "l2tpvpnserver"
xl2tpd[3283]: "debug"
xl2tpd[3283]: "file"
xl2tpd[3283]: "/etc/ppp/options.xl2tpd"
xl2tpd[3283]: "/dev/pts/2"
xl2tpd[3283]: Call established with 192.168.12.166, Local: 50666, Remote: 18490, Serial: 244
xl2tpd[3283]: control_finish: Connection closed to 192.168.12.166, serial 244 ()
xl2tpd[3283]: Terminating pppd: sending TERM signal to pid 4499
xl2tpd[3283]: pppd 4499 successfully terminated

================================================================================

客户端用xl2tpd -D获得到的日志信息是这样的

xl2tpd[1658]: start_pppd: I'm running:
xl2tpd[1658]: "/usr/sbin/pppd"
xl2tpd[1658]: "passive"
xl2tpd[1658]: "nodetach"
xl2tpd[1658]: "refuse-pap"
xl2tpd[1658]: "auth"
xl2tpd[1658]: "require-chap"
xl2tpd[1658]: "name"
xl2tpd[1658]: "zhy"
xl2tpd[1658]: "debug"
xl2tpd[1658]: "file"
xl2tpd[1658]: "/etc/ppp/options.xl2tpd"
xl2tpd[1658]: "/dev/pts/2"
xl2tpd[1658]: child_handler : pppd exited for call 8455 with code 11
xl2tpd[1658]: call_close: Call 46041 to 192.168.9.100 disconnected
xl2tpd[1658]: Terminating pppd: sending TERM signal to pid 2766
xl2tpd[1658]: pppd 2766 successfully terminated

=======================================================================

不知道这是否算是连上了。总是感觉不太对
还有一个比较奇怪的事就是，在两边建立完后，用ifconfig查看时，获得不到PPP的网络接口。

希望懂的帮忙看下。。谢谢