我有一个Debian盒子,我正在尝试将其设置为路由器和Ubuntu盒子,我将其用作客户端.
我的问题是,当Ubuntu客户端尝试ping Internet上的服务器时,所有数据包都会丢失(但是,正如您在下面看到的那样,它们似乎没有问题地转到服务器并返回).
我在Ubuntu Box中这样做：
# ping -I eth1 my.remote-server.com PING my.remote-server.com (X.X.X.X) from 10.1.1.12 eth1: 56(84) bytes of data. ^C --- my.remote-server.com ping statistics --- 13 packets transmitted,0 received,100% packet loss,time 12094ms
(为了隐私,我更改了远程服务器的名称和IP).
从Debian路由器我看到：
# tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed,use -v or -vv for full protocol decode listening on eth1,link-type EN10MB (Ethernet),capture size 65535 bytes IP X.X.X.X > 10.1.1.12: ICMP echo reply,id 305,seq 7,length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request,seq 8,length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply,seq 9,seq 10,seq 11,length 64 ^C 9 packets captured 9 packets received by filter 0 packets dropped by kernel # tcpdump -i eth2 -qtln icmp tcpdump: verbose output suppressed,use -v or -vv for full protocol decode listening on eth2,capture size 65535 bytes IP 192.168.1.10 > X.X.X.X: ICMP echo request,id 360,seq 213,length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply,length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request,seq 214,seq 215,seq 216,seq 217,length 64 ^C 10 packets captured 10 packets received by filter 0 packets dropped by kernel
在远程服务器上,我看到：
# tcpdump -i eth0 -qtln icmp tcpdump: verbose output suppressed,use -v or -vv for full protocol decode listening on eth0,capture size 96 bytes IP Y.Y.Y.Y > X.X.X.X: ICMP echo request,seq 1,length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply,length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request,seq 2,seq 3,seq 4,seq 5,seq 6,length 64 18 packets captured 228 packets received by filter 92 packets dropped by kernel
这里“X.X.X.X”是我的远程服务器的IP,“Y.Y.Y.Y”是我本地网络的公共IP.
所以,我的理解是ping数据包来自Ubuntu框(10.1.1.12),
到路由器(10.1.1.1),从那里到下一个路由器(192.168.1.1)并到达远程服务器(X.X.X.X).然后他们一直回到Debian路由器,但他们从未到达Ubuntu盒子.
我错过了什么？
这是Debian路由器设置：
# ifconfig
eth1 Link encap:Ethernet HWaddr 94:0c:6d:82:0d:98
inet addr:10.1.1.1 Bcast:10.1.1.255 Mask:255.255.255.0
inet6 addr: fe80::960c:6dff:fe82:d98/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:105761 errors:0 dropped:0 overruns:0 frame:0
TX packets:48944 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:40298768 (38.4 MiB) TX bytes:44831595 (42.7 MiB)
Interrupt:19 Base address:0x6000
eth2 Link encap:Ethernet HWaddr 6c:f0:49:a4:47:38
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::6ef0:49ff:fea4:4738/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:38335992 errors:0 dropped:0 overruns:0 frame:0
TX packets:37097705 errors:0 dropped:0 overruns:0 carrier:1
collisions:0 txqueuelen:1000
RX bytes:4260680226 (3.9 GiB) TX bytes:3759806551 (3.5 GiB)
Interrupt:27
eth3 Link encap:Ethernet HWaddr 94:0c:6d:82:c8:72
UP BROADCAST 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:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Interrupt:20 Base address:0x2000
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:3408 errors:0 dropped:0 overruns:0 frame:0
TX packets:3408 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:358445 (350.0 KiB) TX bytes:358445 (350.0 KiB)
tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:2767779 errors:0 dropped:0 overruns:0 frame:0
TX packets:1569477 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:3609469393 (3.3 GiB) TX bytes:96113978 (91.6 MiB)
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.8.0.2 0.0.0.0 255.255.255.255 UH 0 0 0 tun0
127.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 lo
10.8.0.0 10.8.0.2 255.255.255.0 UG 0 0 0 tun0
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth2
10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth2
# arp -n
# Note: Here I have changed all the different MACs except the ones corresponding to the Ubuntu Box (on 10.1.1.12 and 192.168.1.12)
Address HWtype HWaddress Flags Mask Iface
192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.102 ether NN:NN:NN:NN:NN:NN C eth2
10.1.1.12 ether 00:1e:67:15:2b:f0 C eth1
192.168.1.86 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.2 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.40 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.12 ether 00:1e:67:15:2b:f1 C eth2
192.168.1.77 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.41 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.123 ether NN:NN:NN:NN:NN:NN C eth2
# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
# iptables -L -n -t nat
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
MASQUERADE all -- 10.1.1.0/24 !10.1.1.0/24
MASQUERADE all -- !10.1.1.0/24 10.1.1.0/24
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
这是Ubuntu盒子：
# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f1
inet addr:192.168.1.12 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::21e:67ff:fe15:2bf1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:28785139 errors:0 dropped:0 overruns:0 frame:0
TX packets:19050735 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:32068182803 (32.0 GB) TX bytes:6061333280 (6.0 GB)
Interrupt:16 Memory:b1a00000-b1a20000
eth1 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f0
inet addr:10.1.1.12 Bcast:10.1.1.255 Mask:255.255.255.0
inet6 addr: fe80::21e:67ff:fe15:2bf0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:285086 errors:0 dropped:0 overruns:0 frame:0
TX packets:12719 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:30817249 (30.8 MB) TX bytes:2153228 (2.1 MB)
Interrupt:16 Memory:b1900000-b1920000
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:86048 errors:0 dropped:0 overruns:0 frame:0
TX packets:86048 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:11426538 (11.4 MB) TX bytes:11426538 (11.4 MB)
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
0.0.0.0 10.1.1.1 0.0.0.0 UG 100 0 0 eth1
10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
10.8.0.0 192.168.1.10 255.255.255.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
# arp -n
# Note: Here I have changed all the different MACs except the ones corresponding to the Debian Box (on 10.1.1.1 and 192.168.1.10)
Address HWtype HWaddress Flags Mask Iface
192.168.1.70 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.97 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.103 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.13 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.120 (incomplete) eth0
192.168.1.111 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.51 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.102 (incomplete) eth0
192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.74 (incomplete) eth0
192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.121 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.71 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.88 (incomplete) eth0
192.168.1.82 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.98 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.73 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.11 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.85 (incomplete) eth0
192.168.1.112 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.81 ether NN:NN:NN:NN:NN:NN C eth0
10.1.1.1 ether 94:0c:6d:82:0d:98 C eth1
192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.10 ether 6c:f0:49:a4:47:38 C eth0
192.168.1.86 (incomplete) eth0
192.168.1.119 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth1
192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth0
# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
# iptables -L -n -t nat
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
编辑：按照Patrick的建议,我做了一个tcpdump con Ubuntu框,我看到了这个：
# tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed,capture size 65535 bytes IP 10.1.1.12 > X.X.X.X: ICMP echo request,id 21967,length 64 ^C 12 packets captured 12 packets received by filter 0 packets dropped by kernel
所以问题是：如果所有数据包似乎都来了,为什么ping报告100％丢包？
解决方法
从您在评论中的问题：
On the remote server I see requests and replies. But on the Debian router I don’t see anything… on none of the interfaces! My guess is that now,the Ubuntu Box is talking directly to the router on 192.168.1.1 THOUGH sending requests with IP 10.1.1.12,so it can’t route back. But why??
# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 <--- 0.0.0.0 10.1.1.1 0.0.0.0 UG 100 0 0 eth1
在您捕获此路由表时,您有一个较低的度量标准默认值,通过eth0指向您的路由器192.168.1.1(即不是debian机器).始终遵循较低的度量标准默认值,这意味着Ubuntu希望将所有未连接的流量直接发送到192.168.1.1.
如果您有停机时间,请删除该默认值
route del default gw 192.168.1.1 dev eth0
我仍在酝酿更大的问题(原始的嗅探器痕迹显示了对Ubuntu的ping回复：eth1,但操作系统没有接受ping).你可以从Ubuntu ping：eth1并同时捕获Debian：eth2来强制Ubuntu再次通过Debian发送所有流量后演示NAT发生了什么？
