FreeBSD 4.9 外网不通

upon

FreeBSD 4.9，设置了PPPoE，/etc/ppp/ppp.conf内容如下：
#################################################################

default:

set log Phase Chat LCP IPCP CCP tun command
ident user-ppp VERSION (built COMPILATIONDATE)
# Ensure that "device" references the correct serial port
# for your modem. (cuaa0 = COM1, cuaa1 = COM2)
#
set device PPPoE:lnc0
set speed sync
set mru 1492
set mtu 1492
set ctsrts off
enable dns                             # request DNS info (for resolv.conf)

papchap:
#
# edit the next three lines and replace the items in caps with
# the values which have been assigned by your ISP.
#

set authname *******
set authkey *******

set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0 0.0.0.0
add default HISADDR                    # Add a (sticky) default route

#########################################
ifconfig输出如下：
lnc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST>; mtu 1500
        inet 192.168.100.5 netmask 0xffffff00 broadcast 192.168.100.255
        inet6 fe80::250:56ff:fe40:4092%lnc0 prefixlen 64 scopeid 0x1
        ether 00:50:56:40:40:92
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST>; mtu 16384
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
        inet 127.0.0.1 netmask 0xff000000
ppp0: flags=8010<OINTOPOINT,MULTICAST>; mtu 1500
sl0: flags=c010<OINTOPOINT,LINK2,MULTICAST>; mtu 552
faith0: flags=8002<BROADCAST,MULTICAST>; mtu 1500
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST>; mtu 1500
        Opened by PID 55
照理，网络界面已经启动了。/etc/resolv.conf也已经设置了dns服务器的IP地十。ping内网可通。ping 外网，无论IP与域名都不行。
# ping www.google.com
ping: cannot resolve www.google.com: Host name lookup failure
# ping 202.96.111.2
PING 202.96.111.2 (202.96.111.2): 56 data bytes
ping: sendto: No route to host
ping: sendto: No route to host
ping: sendto: No route to host
ping: sendto: No route to host
^C
--- 202.96.111.2 ping statistics ---
4 packets transmitted, 0 packets received, 100% packet loss

注：我是通过交换机与别人共享ADSL上网的，ADSL的工作模式是桥接方式。
FreeBSD装在虚拟机中。

感谢各位高手踊跃发言。

jayvan

PPPoE 拨号还没成功，tun0 没有获得 ip.

upon

经过楼上一位大哥的提示，我重新检查了一下/etc/ppp/ppp.conf文件，参考freebsd hankbook后，把papchap换了个位置，加在set device PPPoE:lnc0的前面，结果果然拨上去了。ifconfig的tun0界面中也有了IP地址，本以为已经搞清楚了。后来，我突发奇想，再把它改过来如何呢？等改回来之后，重新启动，结果ifconfig中没有了tun0界面的IP地址，但ping外网又通了。回头再看ifconfig的输出，也有了tun0界面的IP地址。
现在，已经完全回到了原来的配置，但怎么又好了呢，还是搞不清楚怎么回事。