内容概要：如何使用Internet的IP地址来访问位于DMZ网络中的服务器呢？我在使用公共IP地址来访问DMZ中的服务器一文中提及除了在ISA防火墙的外部接口上绑定多个IP然后做转发外，还可以使用直接在DMZ部署Internet的IP地址，然后在ISP的上游路由器上做路由指向的方式。在这篇文章中，我们就来探讨如何实现这一方案。

如何使用Internet的IP地址来访问位于DMZ网络中的服务器呢？我在使用公共IP地址来访问DMZ中的服务器一文中提及除了在ISA防火墙的外部接口上绑定多个IP然后做转发外，还可以使用直接在DMZ部署Internet的IP地址，然后在ISP的上游路由器上做路由指向的方式。在这篇文章中，我们就来探讨如何实现这一方案。

其实，这已经跳出了ISA防火墙的范畴，更多的是路由/子网的知识。只要网络结构良好的进行规划，部署ISA防火墙是非常容易的。

在国外，IP地址是很容易获得的；而且，你可以一次性为你的网络申请一个完整C类网络的IP地址。但是在国内，一般客户想从ISP获得一个C类网络的IP地址无异是天方夜谭，一般都是几个IP地址。在这个试验中，我们从ISP处获得了五个Internet IP地址，地址范围是从61.139.0.8到61.139.0.12，子网掩码是255.255.255.0。我想在DMZ网络中部署Internet的IP地址，所以我就必须先对获得的Internet IP地址进行子网划分，然后给DMZ网络分配一个子网，最后在ISP的路由器上对我的DMZ子网进行路由指向。

在此过程中，子网划分就显得特别的重要。并且在IP地址的分配过程中，ISA防火墙连接Internet和DMZ的网络适配器各需要一个IP地址，并且子网广播地址和子网网络地址将各耗去一个。所以你可以在DMZ网络中配置的Internet IP地址为你获得的Internet IP地址数减去四。

现在，我们首先需要对获得的Internet IP地址进行子网划分：

将IP地址转换为二进制：

61.139.0.8 00111101 10001011 00000000 00001000

61.139.0.9 00111101 10001011 00000000 00001001

61.139.0.10 00111101 10001011 00000000 00001010

61.139.0.11 00111101 10001011 00000000 00001011

61.139.0.12 00111101 10001011 00000000 00001100

注意看，前面四个IP地址（61.139.0.8～61.139.0.11）都是位于61.139.0.8/30子网中，所以，我们可以在DMZ网络中部署此子网，然后在ISA连接外部网络（Internet）上的网络适配器上配置61.139.0.12/24这个IP地址。

但是在61.139.0.8/30这个子网中，61.139.0.8/30是子网网络地址，61.139.0.11/30是子网广播地址，都不能给网络中的主机进行使用。然后我们在ISA防火墙连接DMZ的接口上配置61.139.0.9/252这个IP地址，那么就只剩下61.139.0.10/30这个IP地址可以配置给DMZ网络中的服务器使用了。

试验用的网络拓朴结构如下图所示：

各计算机的TCP/IP配置情况如下，此次试验不涉及DNS解析，各计算机的DNS服务器均设置为空：

External1：

• IP：61.139.0.1/24；
• DG：61.139.0.1；

ISA 2004 Firewall：

External接口：

• IP：61.139.0.12/24
• DG：61.139.0.1；

DMZ接口：

• IP：61.139.0.9/30；
• DG：None；

Interna接口：

• IP：192.168.0.1/24；
• DG：None；

Ftp1：

• IP：61.139.0.10/30；
• DG：61.139.0.9；

Client1：

• IP：192.168.0.8/24；
• DG：192.168.0.1；

在这个试验中，我们按照以下步骤进行：

• 使用三向外围模板配置ISA防火墙；
• 修改访问规则；
• 测试各个网络间的连通性一；
• 在外部主机上配置到DMZ网络的路由；
• 测试各个网络间的连通性二；

1、使用三向外围模板配置ISA防火墙；

打开ISA防火墙管理控制台，点击配置下的网络，然后在右边的任务面板的模版标签中，点击3向外围网络，

在弹出的欢迎使用网络模版向导对话框，点击下一步；

在导出ISA服务器的配置页，点击下一步；

在内部网络IP地址页，由于我们在安装时已经进行了配置，所以直接点击下一步；如果没有配置，你可以通过自行添加；

在外向网络IP地址页，点击添加适配器；

在弹出的选择网卡对话框，勾选DMZ，然后点击确定；

然后在外围网络IP地址页，点击下一步；

在选择一个防火墙策略页，选择允许无限制的访问，点击下一步；

最后在正在完成网络模版页，点击完成。

现在，你可以在网络规则中看到，内部到外围（DMZ）、外部都是NAT方式，外围到外部是路由方式。关于配置DMZ网络更多的信息，请参见在ISA Server 2004中配置DMZ网络一文。

2、修改访问规则

此时，防火墙策略如下图所示，

为了更好的进行演示，我们需要进行修改。双击无限制的Internet访问，将其源网络和目的网络均修改为所有网络（和本地主机），然后删除第二条规则VPN客户端到内部网络的访问，修改后的规则如下图所示：

点击应用以保存修改和更新防火墙策略。

3、测试各个网络间的连通性一

现在我们来测试一下各网络间的连通性，首先在内部网络的Client1上进行测试：

/* 在Client1上进行测试*/

C:/Documents and Settings/Administrator>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : mine

Primary Dns Suffix . . . . . . . :

Node Type . . . . . . . . . . . . : Unknown

IP Routing Enabled. . . . . . . . : No

WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Loopback:

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Microsoft Loopback Adapter

Physical Address. . . . . . . . . : 02-00-4C-4F-4F-50

Dhcp Enabled. . . . . . . . . . . : No

IP Address. . . . . . . . . . . . : 192.168.0.8

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.168.0.1

/* Ping自己的网关（ISA防火墙的内部接口）*/
C:/Documents and Settings/Administrator>ping 192.168.0.1 -n 2

Pinging 192.168.0.1 with 32 bytes of data:

Reply from 192.168.0.1: bytes=32 time=4ms TTL=128

Reply from 192.168.0.1: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.0.1:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 4ms, Average = 2ms

/* Ping ISA防火墙的外部接口*/
C:/Documents and Settings/Administrator>ping 61.139.0.12 -n 2

Pinging 61.139.0.12 with 32 bytes of data:

Reply from 61.139.0.12: bytes=32 time<1ms TTL=128

Reply from 61.139.0.12: bytes=32 time=10ms TTL=128

Ping statistics for 61.139.0.12:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 10ms, Average = 5ms

/* Ping ISA防火墙的DMZ网络接口*/
C:/Documents and Settings/Administrator>ping 61.139.0.9 -n 2

Pinging 61.139.0.9 with 32 bytes of data:

Reply from 61.139.0.9: bytes=32 time=2ms TTL=128

Reply from 61.139.0.9: bytes=32 time<1ms TTL=128

Ping statistics for 61.139.0.9:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 2ms, Average = 1ms

/* Ping DMZ网络中的主机Ftp1*/

C:/Documents and Settings/Administrator>ping 61.139.0.10 -n 2

Pinging 61.139.0.10 with 32 bytes of data:

Reply from 61.139.0.10: bytes=32 time=1ms TTL=127

Reply from 61.139.0.10: bytes=32 time=2ms TTL=127

Ping statistics for 61.139.0.10:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 1ms, Maximum = 2ms, Average = 1ms

/* Ping 外部网络中的主机External1*/
C:/Documents and Settings/Administrator>ping 61.139.0.1 -n 2

Pinging 61.139.0.1 with 32 bytes of data:

Reply from 61.139.0.1: bytes=32 time=2ms TTL=127

Reply from 61.139.0.1: bytes=32 time=2ms TTL=127

Ping statistics for 61.139.0.1:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 2ms, Maximum = 2ms, Average = 2ms

测试都是通过的。

现在我们在ISA防火墙上进行测试：

/* 在ISA防火墙上进行测试*/

C:/Documents and Settings/Administrator>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Florence

Primary Dns Suffix . . . . . . . :

Node Type . . . . . . . . . . . . : Unknown

IP Routing Enabled. . . . . . . . : Yes

WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter DMZ:

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Intel 21140-Based PCI Fast Ethernet Adapter (Generic) #2

Physical Address. . . . . . . . . : 00-03-FF-7E-BC-3B

DHCP Enabled. . . . . . . . . . . : No

IP Address. . . . . . . . . . . . : 61.139.0.9

Subnet Mask . . . . . . . . . . . : 255.255.255.252

Default Gateway . . . . . . . . . :

Ethernet adapter Internal:

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Intel 21140-Based PCI Fast Ethernet Adapter (Generic)

Physical Address. . . . . . . . . : 00-03-FF-EE-45-8D

DHCP Enabled. . . . . . . . . . . : No

IP Address. . . . . . . . . . . . : 192.168.0.1

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . :

Ethernet adapter External:

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Intel 21140-Based PCI Fast Ethernet Adapter (Generic) #3

Physical Address. . . . . . . . . : 00-03-FF-FC-FF-FF

DHCP Enabled. . . . . . . . . . . : No

IP Address. . . . . . . . . . . . : 61.139.0.12

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 61.139.0.1

/* Ping 位于内部网络中的Client1*/

C:/Documents and Settings/Administrator>ping 192.168.0.8

Pinging 192.168.0.8 with 32 bytes of data:

Reply from 192.168.0.8: bytes=32 time<1ms TTL=128

Reply from 192.168.0.8: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.0.8:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 0ms, Average = 0ms

/* Ping 位于DMZ网络中的Ftp1*/

C:/Documents and Settings/Administrator>ping 61.139.0.10

Pinging 61.139.0.10 with 32 bytes of data:

Reply from 61.139.0.10: bytes=32 time=2ms TTL=128

Reply from 61.139.0.10: bytes=32 time=2ms TTL=128

Ping statistics for 61.139.0.10:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 2ms, Maximum = 2ms, Average = 2ms

/* Ping 位于外部网络中的External1*/

C:/Documents and Settings/Administrator>ping 61.139.0.1

Pinging 61.139.0.1 with 32 bytes of data:

Reply from 61.139.0.1: bytes=32 time=20ms TTL=128

Reply from 61.139.0.1: bytes=32 time=1ms TTL=128

Ping statistics for 61.139.0.1:

Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 1ms, Maximum = 20ms, Average = 10ms
　

测试也都是通过的。

现在我们在位于DMZ网络中的Ftp1上进行测试：

/* 在ISA防火墙上进行测试*/

C:/Documents and Settings/Administrator>ipconfig

Windows IP Configuration

Ethernet adapter DMZ:

Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 61.139.0.10
Subnet Mask . . . . . . . . . . . : 255.255.255.252
Default Gateway . . . . . . . . . : 61.139.0.9
　

/* Ping ISA防火墙的DMZ接口*/

C:/Documents and Settings/Administrator>ping 61.139.0.9 -n 2

Pinging 61.139.0.9 with 32 bytes of data:

Reply from 61.139.0.9: bytes=32 time=3ms TTL=128

Ping statistics for 61.139.0.9:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 3ms, Maximum = 3ms, Average = 3ms
Control-C
^C

/* Ping ISA防火墙的外部网络接口*/
C:/Documents and Settings/Administrator>ping 61.139.0.12 -n 2

Pinging 61.139.0.12 with 32 bytes of data:

Reply from 61.139.0.12: bytes=32 time=2ms TTL=128

Ping statistics for 61.139.0.12:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 2ms, Average = 2ms
Control-C
^C

/* Ping 位于Internet的主机External1*/
C:/Documents and Settings/Administrator>ping 61.139.0.1 -n 2

Pinging 61.139.0.1 with 32 bytes of data:

Request timed out.

Ping statistics for 61.139.0.1:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),
Control-C
^C
　

测试没有通过，Why？

最后，我们在Internet的主机External1上进行测试：

/* 在External上进行测试*/

C:/Documents and Settings/Administrator>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Sydney
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel 21140-Based PCI Fast Ethernet Adapt
er (Generic)
Physical Address. . . . . . . . . : 00-03-FF-FF-36-DB
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 61.139.0.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 61.139.0.1
　

/* Ping ISA防火墙的外部网络接口*/
C:/Documents and Settings/Administrator>ping 61.139.0.12 -n 2

Pinging 61.139.0.12 with 32 bytes of data:

Reply from 61.139.0.12: bytes=32 time=4ms TTL=128

Ping statistics for 61.139.0.12:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 4ms, Maximum = 4ms, Average = 4ms
Control-C
^C
　

/* Ping ISA防火墙的DMZ网络接口*/

C:/Documents and Settings/Administrator>ping 61.139.0.9 -n 2

Pinging 61.139.0.9 with 32 bytes of data:

Request timed out.

Ping statistics for 61.139.0.9:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),
Control-C
^C
　

/* Ping 位于DMZ网络的主机Ftp1*/
C:/Documents and Settings/Administrator>ping 61.139.0.10 -n 2

Pinging 61.139.0.10 with 32 bytes of data:

Request timed out.

Ping statistics for 61.139.0.10:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),
Control-C
^C
　

也没有通过，Why？

答案是在External1上没有到DMZ网络的路由。

查看一下External1上的路由表：

C:/Documents and Settings/Administrator>route print

IPv4 Route Table
======================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x10003 ...00 03 ff ff 36 db ...... Intel 21140-Based PCI Fast Ethernet Adapte
(Generic)
========================================================
========================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 61.139.0.1 61.139.0.1 20
61.139.0.0 255.255.255.0 61.139.0.1 61.139.0.1 20
61.139.0.1 255.255.255.255 127.0.0.1 127.0.0.1 20
61.255.255.255 255.255.255.255 61.139.0.1 61.139.0.1 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
224.0.0.0 240.0.0.0 61.139.0.1 61.139.0.1 20
255.255.255.255 255.255.255.255 61.139.0.1 61.139.0.1 1
Default Gateway: 61.139.0.1
=====================================================
Persistent Routes:
None

注意看，61.139.0.0网络是通过61.139.0.1这个接口访问的，External1会通过61.139.0.1对61.139.0.0/24网络的数据包进行广播，那么位于DMZ网络中的61.139.0.9、61.139.0.10自然不能获得External发送的数据包。

4、在外部主机上配置到DMZ网络的路由

现在我们在External1上配置到DMZ网络的路由：

C:/Documents and Settings/Administrator>route add 61.139.0.8 mask 255.255.255.252 61.139.0.12

C:/Documents and Settings/Administrator>route print

IPv4 Route Table
======================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x10003 ...00 03 ff ff 36 db ...... Intel 21140-Based PCI Fast Ethernet Adapter
(Generic)
=====================================================
=====================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 61.139.0.1 61.139.0.1 20
61.139.0.0 255.255.255.0 61.139.0.1 61.139.0.1 20
61.139.0.1 255.255.255.255 127.0.0.1 127.0.0.1 20
61.139.0.8 255.255.255.252 61.139.0.12 61.139.0.1 1
61.255.255.255 255.255.255.255 61.139.0.1 61.139.0.1 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
224.0.0.0 240.0.0.0 61.139.0.1 61.139.0.1 20
255.255.255.255 255.255.255.255 61.139.0.1 61.139.0.1 1
Default Gateway: 61.139.0.1
======================================================
Persistent Routes:
None

5、测试各个网络间的连通性二

现在，我们再在External1上进行测试：

/* Ping ISA防火墙的DMZ网络接口*/

C:/Documents and Settings/Administrator>ping 61.139.0.9 -n 2

Pinging 61.139.0.9 with 32 bytes of data:

Reply from 61.139.0.9: bytes=32 time=2ms TTL=128

Ping statistics for 61.139.0.9:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 2ms, Average = 2ms
Control-C
^C

/* Ping 位于DMZ网络的主机Ftp1*/
C:/Documents and Settings/Administrator>ping 61.139.0.10 -n 2

Pinging 61.139.0.10 with 32 bytes of data:

Reply from 61.139.0.10: bytes=32 time=3ms TTL=127
Reply from 61.139.0.10: bytes=32 time=1ms TTL=127

Ping statistics for 61.139.0.10:
Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 3ms, Average = 2ms
　

/* 访问主机Ftp1上的Ftp服务*/
C:/Documents and Settings/Administrator>ftp 61.139.0.10
Connected to 61.139.0.10.
220 Serv-U FTP Server v6.0 for WinSock ready...
User (61.139.0.10:(none)): anonymous
331 User name okay, please send complete E-mail address as password.
Password:
230 User logged in, proceed.
ftp>

此时，在Ftp1上的ftp服务的管理控制台，你可以看到：

此次试验就成功完成了。

从以上试验可以看出，在DMZ网络中部署Internet IP地址，除了了三个IP地址的损耗外，还需要在ISP的路由器上进行路由配置。所以，一般情况下，不推荐你在DMZ网络中直接部署Internet的IP地址，推荐你采用ISA防火墙绑定多个外部IP，然后使用不同的地址进行DMZ网络中服务的发布，具体配置可以参见使用公共IP地址来访问DMZ中的服务器一文。