我正在尝试让 PPTPD 在专用的 debian-squeeze 服务器上运行。我可以正常连接到 VPN，但无法访问互联网。只能访问本地网络。
这是客户端连接到 VPN、尝试 ping google 然后再次断开连接的日志文件。
Apr 5 21:41:23 ks3094571 pptpd[14669]: CTRL: Client xx.xx.xx.xx control connection started
Apr 5 21:41:23 ks3094571 pptpd[14669]: CTRL: Starting call (launching pppd, opening GRE)
Apr 5 21:41:23 ks3094571 pppd[14670]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
Apr 5 21:41:23 ks3094571 pppd[14670]: pptpd-logwtmp: $Version$
Apr 5 21:41:23 ks3094571 pppd[14670]: pppd 2.4.5 started by root, uid 0
Apr 5 21:41:23 ks3094571 pppd[14670]: using channel 5
Apr 5 21:41:23 ks3094571 pppd[14670]: Using interface ppp0
Apr 5 21:41:23 ks3094571 pppd[14670]: Connect: ppp0 <--> /dev/pts/0
Apr 5 21:41:23 ks3094571 pppd[14670]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x26efc6d1> <pcomp> <accomp>]
Apr 5 21:41:23 ks3094571 pptpd[14669]: GRE: Bad checksum from pppd.
Apr 5 21:41:23 ks3094571 pppd[14670]: rcvd [LCP ConfReq id=0x0 <mru 1400> <magic 0x24246dcb> <pcomp> <accomp> <callback CBCP>]
Apr 5 21:41:23 ks3094571 pppd[14670]: sent [LCP ConfRej id=0x0 <callback CBCP>]
Apr 5 21:41:23 ks3094571 pppd[14670]: rcvd [LCP ConfReq id=0x1 <mru 1400> <magic 0x24246dcb> <pcomp> <accomp>]
Apr 5 21:41:23 ks3094571 pppd[14670]: sent [LCP ConfAck id=0x1 <mru 1400> <magic 0x24246dcb> <pcomp> <accomp>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x26efc6d1> <pcomp> <accomp>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x26efc6d1> <pcomp> <accomp>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [LCP EchoReq id=0x0 magic=0x26efc6d1]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [CHAP Challenge id=0xd0 <35f0fe89f1170893b568ba7e6611e44f>, name = "pptpd"]
Apr 5 21:41:26 ks3094571 pptpd[14669]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [LCP Ident id=0x2 magic=0x24246dcb "MSRASV5.20"]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [LCP Ident id=0x3 magic=0x24246dcb "MSRAS-0-HENK-PC"]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [LCP Ident id=0x4 magic=0x24246dcb "mH\37777777610\37777777700\377777776668\37777777762K\37777777644\025\37777777736C\037vh+"]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [LCP EchoRep id=0x0 magic=0x24246dcb]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [CHAP Response id=0xd0 <3b00a54322dc36481e4a79fba7ae0ed400000000000000009421753c925608fd17dffd234915c1859dc9648f00b9c53e00>, name = "henk"]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [CHAP Success id=0xd0 "S=513269C2A7CDE51B9253B04C5CE05F67E4F38CA4 M=Access granted"]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [CCP ConfReq id=0x1 <mppe +H -M +S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [IPV6CP ConfReq id=0x5 <addr fe80::c43f:f009:f7ad:bf5c>]
Apr 5 21:41:26 ks3094571 pppd[14670]: Unsupported protocol 'IPv6 Control Protocol' (0x8057) received
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [LCP ProtRej id=0x2 80 57 01 05 00 0e 01 0a c4 3f f0 09 f7 ad bf 5c]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [CCP ConfReq id=0x6 <mppe +H -M -S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [CCP ConfNak id=0x6 <mppe +H -M +S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [IPCP ConfReq id=0x7 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-wins 0.0.0.0> <ms-dns2 0.0.0.0> <ms-wins 0.0.0.0>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [IPCP TermAck id=0x7]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [CCP ConfAck id=0x1 <mppe +H -M +S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [CCP ConfReq id=0x8 <mppe +H -M +S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [CCP ConfAck id=0x8 <mppe +H -M +S -L -D -C>]
Apr 5 21:41:26 ks3094571 pppd[14670]: MPPE 128-bit stateless compression enabled
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 10.0.0.1>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [IPCP ConfRej id=0x1 <compress VJ 0f 01>]
Apr 5 21:41:26 ks3094571 pppd[14670]: sent [IPCP ConfReq id=0x2 <addr 10.0.0.1>]
Apr 5 21:41:26 ks3094571 pppd[14670]: rcvd [IPCP ConfAck id=0x2 <addr 10.0.0.1>]
Apr 5 21:41:27 ks3094571 pppd[14670]: rcvd [IPCP ConfReq id=0x9 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-wins 0.0.0.0> <ms-dns2 0.0.0.0> <ms-wins 0.0.0.0>]
Apr 5 21:41:27 ks3094571 pppd[14670]: sent [IPCP ConfRej id=0x9 <ms-dns1 0.0.0.0> <ms-wins 0.0.0.0> <ms-dns2 0.0.0.0> <ms-wins 0.0.0.0>]
Apr 5 21:41:27 ks3094571 pppd[14670]: rcvd [IPCP ConfReq id=0xa <addr 0.0.0.0>]
Apr 5 21:41:27 ks3094571 pppd[14670]: sent [IPCP ConfNak id=0xa <addr 10.0.0.10>]
Apr 5 21:41:27 ks3094571 pppd[14670]: rcvd [IPCP ConfReq id=0xb <addr 10.0.0.10>]
Apr 5 21:41:27 ks3094571 pppd[14670]: sent [IPCP ConfAck id=0xb <addr 10.0.0.10>]
Apr 5 21:41:27 ks3094571 pppd[14670]: Cannot determine ethernet address for proxy ARP
Apr 5 21:41:27 ks3094571 pppd[14670]: local IP address 10.0.0.1
Apr 5 21:41:27 ks3094571 pppd[14670]: remote IP address 10.0.0.10
Apr 5 21:41:27 ks3094571 pppd[14670]: pptpd-logwtmp.so ip-up ppp0 *username* xx.xx.xx.xx
Apr 5 21:41:27 ks3094571 pppd[14670]: Script /etc/ppp/ip-up started (pid 14674)
Apr 5 21:41:27 ks3094571 pppd[14670]: Script /etc/ppp/ip-up finished (pid 14674), status = 0x0
最让我困扰的是Unsupported protocol 'IPv6 Control Protocol' (0x8057) received和Cannot determine ethernet address for proxy ARP。我尝试用谷歌搜索这些，但没有找到任何有用的信息。
有人能明白发生了什么事吗？
额外信息：
配置文件（屏蔽 IP）
dummy0 Link encap:Ethernet HWaddr fa:5c:5a:6d:82:c0
BROADCAST NOARP MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
eth0 Link encap:Ethernet HWaddr 00:27:0e:0d:8b:1a
inet addr:xx.xxx.xxx.81 Bcast:xx.xxx.xxx.255 Mask:255.255.255.0
inet6 addr: fe80::227:eff:fe0d:8b1a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:815531610 errors:0 dropped:13039 overruns:0 frame:0
TX packets:1043715428 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:654503248866 (609.5 GiB) TX bytes:1074622704549 (1000.8 GiB)
Interrupt:43 Base address:0x6000
ip6tnl0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
NOARP MTU:1452 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1852194 errors:0 dropped:0 overruns:0 frame:0
TX packets:1852194 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2482791079 (2.3 GiB) TX bytes:2482791079 (2.3 GiB)
sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:1.2.3.1 P-t-P:1.2.3.2 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
tunl0 Link encap:IPIP Tunnel HWaddr
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
PPTPD安装过程：
#mknod /dev/ppp c 108 0
#apt-get update
#apt-get install pptpd
#vim /etc/ppp/pptpd-options
add
-----------------------------------
ms-dns 8.8.8.8
ms-dns 8.8.4.4
-----------------------------------
#cp -R /etc/ppp/pptpd-options /etc/pptpd.conf
#vim /etc/pptpd.conf
add
-----------------------------------
localip 10.0.0.1
remoteip 10.0.0.10-100
-----------------------------------
#vim /etc/ppp/chap-secrets
add
-----------------------------------
johndoe pptpd johndoepassword *
-----------------------------------
#vim /etc/sysctl.conf
-----------------------------------
net.ipv4.ip_forward = 1
-----------------------------------
#/sbin/iptables -P FORWARD ACCEPT
#/sbin/iptables --table nat -A POSTROUTING -o eth0 -j MASQUERADE