我设置了一个openstack环境并创建了几个vms。 vms如下：
root@controller:~# nova list
+--------------------------------------+----------+--------+----------------------------------+
| ID | Name | Status | Networks |
+--------------------------------------+----------+--------+----------------------------------+
| 2a2dbaa8-8ae1-47c9-a9c1-516ef8b955ba | key1 | ACTIVE | private=10.0.0.11, 172.16.10.114 |
| 6f2831d0-8263-40de-8ebc-9ed9f8eab905 | keytest | ACTIVE | private=10.0.0.10, 172.16.10.123 |
| 7f732f7b-d19e-42da-bf9e-b2c2c3e401af | t2 | ACTIVE | private=10.0.0.4, 172.16.10.121 |
| e858db20-20a6-43d2-bac8-45a0ade319f4 | test0001 | ACTIVE | private=10.0.0.13 |
| d1ca2f5d-ba09-47af-8126-b68e38ded582 | tt01 | ACTIVE | private=10.0.0.12 |
| cae980d4-3973-49ad-ba76-94d5284a849a | zls01 | ACTIVE | private=10.0.0.14, 172.16.10.124 |
+--------------------------------------+----------+--------+----------------------------------+
10.0.0.0/24是内部网络，172.16.10.0 / 24是floaing ips。
我在我的vm tt01（10.0.0.12）中ping 8.8.8.8
root@controller:~# ssh root@10.0.0.12
root@10.0.0.12's password:
Permission denied, please try again.
root@10.0.0.12's password:
Last login: Thu Oct 23 14:16:10 2014 from 10.0.0.5
[root@tt01 ~]#
[root@tt01 ~]#
[root@tt01 ~]#
[root@tt01 ~]# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=27 time=287 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=27 time=286 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=27 time=289 ms
^C
我使用tcpdump捕获网络数据包，如下所示：
root@controller:~# tcpdump icmp -ee -n -v -i any
tcpdump: listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
14:18:24.972228 P fa:16:3e:ca:a8:8e ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
10.0.0.12 > 8.8.8.8: ICMP echo request, id 34381, seq 1, length 64
14:18:24.972228 In fa:16:3e:ca:a8:8e ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
10.0.0.12 > 8.8.8.8: ICMP echo request, id 34381, seq 1, length 64
14:18:24.972280 Out 00:1e:67:45:85:ac ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.10.15 > 8.8.8.8: ICMP echo request, id 34381, seq 1, length 64
14:18:25.259378 In 00:12:7f:7d:37:a1 ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 28, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 172.16.10.15: ICMP echo reply, id 34381, seq 1, length 64
14:18:25.259401 Out 00:1e:67:45:85:ad ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 27, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 10.0.0.12: ICMP echo reply, id 34381, seq 1, length 64
14:18:25.259407 Out 00:1e:67:45:85:ad ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 27, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 10.0.0.12: ICMP echo reply, id 34381, seq 1, length 64
14:18:25.972520 P fa:16:3e:ca:a8:8e ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
10.0.0.12 > 8.8.8.8: ICMP echo request, id 34381, seq 2, length 64
14:18:25.972520 In fa:16:3e:ca:a8:8e ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
10.0.0.12 > 8.8.8.8: ICMP echo request, id 34381, seq 2, length 64
14:18:25.972557 Out 00:1e:67:45:85:ac ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.10.15 > 8.8.8.8: ICMP echo request, id 34381, seq 2, length 64
14:18:26.258533 In 00:12:7f:7d:37:a1 ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 28, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 172.16.10.15: ICMP echo reply, id 34381, seq 2, length 64
14:18:26.258557 Out 00:1e:67:45:85:ad ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 27, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 10.0.0.12: ICMP echo reply, id 34381, seq 2, length 64
14:18:26.258562 Out 00:1e:67:45:85:ad ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 27, id 0, offset 0, flags [none], proto ICMP (1), length 84)
8.8.8.8 > 10.0.0.12: ICMP echo reply, id 34381, seq 2, length 64
14:18:26.972630 P fa:16:3e:ca:a8:8e ethertype IPv4 (0x0800), length 100: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
根据iptables我知道有一个snat，10.0.0.12被翻译为172.16.10.15。
root@controller:~# iptables -t nat -S nova-network-snat
-N nova-network-snat
-A nova-network-snat -j nova-network-float-snat
-A nova-network-snat -s 10.0.0.0/24 -o eth1 -j SNAT --to-source 172.16.10.15
所以我的问题是，当icmp echo reply数据包到达172.16.10.15时，它应该如何将172.16.10.15转换为10.0.0.12？