Cisco基础(五)：配置静态NAT、配置端口映射、配置动态NAT、PAT配置、办公区Internet的访问

2022-05-09 21:53:56

一、配置静态NAT

目标：

随着接入Internet的计算机数量的不断猛增，IP地址资源也就愈加显得捉襟见肘。事实上，除了中国教育和科研计算机网（CERNET）外，一般用户几乎申请不到整段的C类IP地址。在其他ISP那里，即使是拥有几百台计算机的大型局域网用户，当他们申请IP地址时，所分配的地址也不过只有几个或十几个IP地址。显然，这样少的IP地址根本无法满足网络用户的需求。

在R1上配置静态NAT使192.168.1.1转换为61.159.62.131，192.168.1.2转换为61.159.62.132，实现外部网络访问。

方案：

借助于NAT，私有（保留）地址的"内部"网络通过路由器发送数据包时，私有地址被转换成合法的IP地址，一个局域网只需使用少量IP地址（甚至是1个）即可实现私有地址网络内所有计算机与Internet的通信需求。

这种通过使用少量的公有IP 地址代表较多的私有IP 地址的方式，将有助于减缓可用IP地址空间的枯竭。而且还能够有效地避免来自网络外部的攻击，隐藏并保护网络内部的计算机。

网络拓扑如下图所示：

步骤：

步骤一：通用配置

1）配置R1端口IP地址，以及默认路由

tarena-R1(config)#interface f0/0
    tarena-R1(config-if)#ip address 192.168.1.254 255.255.255.0
    tarena-R1(config-if)#no shutdown
    tarena-R1(config-if)#interface f0/1
    tarena-R1(config-if)#ip address 61.159.62.129 255.255.255.248
    tarena-R1(config-if)#no shutdown
    tarena-R1(config-if)#exit
    tarena-R1(config)#ip route 0.0.0.0 0.0.0.0 f0/1

2）配置R2端口IP地址

不需要在R2上配置到企业内网的静态路由，因为NAT的存在，企业内部的地址都将被转换、隐藏。

tarena-R2(config)#interface f0/0
    tarena-R2(config-if)#ip address 61.159.62.130 255.255.255.248
    tarena-R2(config-if)#no shutdown
    tarena-R2(config-if)#interface f0/1
    tarena-R2(config-if)#ip address 192.168.2.254 255.255.255.0
    tarena-R2(config-if)#no shutdown

步骤二：静态NAT配置

1）在R1上将192.168.1.1映射到61.159.62.131，将192.168.1.2映射到61.159.62.132

静态映射有唯一对应的关系。

通过静态NAT，可以把内网服务器发布到外网。

tarena-R1(config)#ip nat inside source static 192.168.1.1 61.159.62.131
tarena-R1(config)#ip nat inside source static 192.168.1.2 61.159.62.132

2）在R1上配置NAT内、外端口

tarena-R1(config)#interface f0/0
    tarena-R1(config-if)#ip nat inside
    tarena-R1(config-if)#interface f0/1
    tarena-R1(config-if)#ip nat outside

3）分别在两台PC机上测试到外网主机的通信

PC1测试如下所示：

PC>ipconfig
    FastEthernet0 Connection:(default port)
    Link-local IPv6 Address.........: FE80::2D0:FFFF:FE45:CACC
    IP Address......................: 192.168.1.1
    Subnet Mask.....................: 255.255.255.0
    Default Gateway.................: 192.168.1.254
    PC>ping 192.168.2.1
    Pinging 192.168.2.1 with 32 bytes of data:
    Reply from 192.168.2.1: bytes=32 time=1ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Ping statistics for 192.168.2.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms
    PC>

PC2的测试如下所示：

PC>ipconfig
    FastEthernet0 Connection:(default port)
    Link-local IPv6 Address.........: FE80::200:CFF:FEEA:DE30
    IP Address......................: 192.168.1.2
    Subnet Mask.....................: 255.255.255.0
    Default Gateway.................: 192.168.1.254
    PC>ping 192.168.2.1
    Pinging 192.168.2.1 with 32 bytes of data:
    Request timed out.
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Ping statistics for 192.168.2.1:
    Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms
    PC>

4）在R1上查看NAT转换表

tarena-R1#show ip nat translations
    Pro Inside global Inside local Outside local Outside global
    icmp 61.159.62.131:10 192.168.1.1:10 192.168.2.1:10 192.168.2.1:10
    icmp 61.159.62.131:11 192.168.1.1:11 192.168.2.1:11 192.168.2.1:11
    icmp 61.159.62.131:12 192.168.1.1:12 192.168.2.1:12 192.168.2.1:12
    icmp 61.159.62.131:9 192.168.1.1:9 192.168.2.1:9 192.168.2.1:9
    icmp 61.159.62.132:27 192.168.1.2:27 192.168.2.1:27 192.168.2.1:27
    icmp 61.159.62.132:28 192.168.1.2:28 192.168.2.1:28 192.168.2.1:28
    icmp 61.159.62.132:29 192.168.1.2:29 192.168.2.1:29 192.168.2.1:29
    icmp 61.159.62.132:30 192.168.1.2:30 192.168.2.1:30 192.168.2.1:30

二、配置端口映射

目标：

通过端口映射技术将内部服务器发布向Internet。

方案：

在R1上配置端口映射将192.168.1.3的80端口映射为61.159.62.133的80端口，将web服务器发布到Internet。网络拓扑如下图所示：

步骤：

步骤一：通用配置

1）在案例一基础上取消静态转换条目，在192.168.1.0网络新增一台web服务器IP为192.168.1.3。将192.168.1.3的80端口映射为61.159.62.133的80端口

tarena-R1(config)#no ip nat inside source static 192.168.1.1 61.159.62.131
tarena-R1(config)#no ip nat inside source static 192.168.1.2 61.159.62.132
tarena-R1 (config)#ip nat inside source static tcp 192.168.1.3 80 61.159.62.133 80

步骤二：PC3*问web服务器进行验证

1）外部主机PC4*问61.159.62.133进行验证，如下图所示

三、配置动态NAT

目标：

在R1通过动态NAT实现企业内网192.168.1.0/24转换为公网地址61.159.62.131-61.159.62.134，访问192.168.2.1

方案：

网络拓扑如下图所示：

步骤：

步骤一：动态NAT配置

1）删除案例2中的端口映射

tarena-R1 (config)#no ip nat inside source static tcp 192.168.1.3 80 61.159.62.133 80

2）在R1上配置ACL

tarena-R1(config)#access-list 1 permit 192.168.1.0 0.0.0.255

3）在R1上配置可转换的公网IP地址池

地址池是向ISP（Internet服务提供商，如电信、联通）申请得到的，内网主机（上一步ACL中所包含的IP地址）到外网的访问，内网地址将被动态的、随机的转换为这些合法地址。

tarena-R1(config)#ip nat pool natpool 61.159.62.131 61.159.62.134 netmask 255.255.255.248

4）关联ACL和公网的IP地址池

tarena-R1(config)#ip nat inside source list 1 pool natpool

5）在R1上配置NAT内、外端口

tarena-R1(config)#interface f0/0
    tarena-R1(config-if)#ip nat inside
    tarena-R1(config-if)#interface f0/1
    tarena-R1(config-if)#ip nat outside

6）分别在两台PC机上测试到外网主机的通信

PC1测试如下所示：

PC2测试如下所示：

PC>ipconfig
    FastEthernet0 Connection:(default port)
    Link-local IPv6 Address.........: FE80::2D0:FFFF:FE45:CACC
    IP Address......................: 192.168.1.2
    Subnet Mask.....................: 255.255.255.0
    Default Gateway.................: 192.168.1.254
    PC>ping 192.168.2.1
    Pinging 192.168.2.1 with 32 bytes of data:
    Reply from 192.168.2.1: bytes=32 time=1ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
    Ping statistics for 192.168.2.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms

7）在R1上查看NAT转换表

转换表中的对应关系是动态的，如192.168.1.1被转换为61.159.62.131，但是下一次对外网的访问很有可能被转换为其他地址。

tarena-R1#show ip nat translations
    Pro Inside global Inside local Outside local Outside global
    icmp 61.159.62.131:1362192.168.1.1:1362 192.168.2.1:1362 192.168.2.1:1362
    icmp 61.159.62.131:1392192.168.1.1:1392 192.168.2.1:1392 192.168.2.1:1392
    icmp 61.159.62.131:1393192.168.1.1:1393 192.168.2.1:1393 192.168.2.1:1393
    icmp 61.159.62.131:1394192.168.1.1:1394 192.168.2.1:1394 192.168.2.1:1394
    icmp 61.159.62.132:13 192.168.1.2:13 192.168.2.1:13 192.168.2.1:13
    icmp 61.159.62.132:14 192.168.1.2:14 192.168.2.1:14 192.168.2.1:14
    icmp 61.159.62.132:15 192.168.1.2:15 192.168.2.1:15 192.168.2.1:15
    icmp 61.159.62.132:16 192.168.1.2:16 192.168.2.1:16 192.168.2.1:16

四、PAT配置

目标：

在R1配置PAT端口多路复用使企业内网192.168.1.0/24复用f0/1端口的IP，实现外部网络的访问。

方案：

网络拓扑如下图所示：

步骤：

步骤一：基于端口的PAT配置限制

1）删除案例3中动态NAT配置

tarena-R1(config)#no ip nat inside source list 1
tarena-R1(config)#no ip nat pool natpool
tarena-R1(config)#no access-list 1

2）在R1上配置ACL

tarena-R1(config)#access-list 1 permit 192.168.1.0 0.0.0.255

3）关联ACL和路由器连接互联网的端口

该命令最后加上的overload表示复用。

tarena-R1(config)#ip nat inside source list 1 interface f0/1 overload

4）在R1上配置NAT内、外端口

tarena-R1(config)#interface f0/0
    tarena-R1(config-if)#ip nat inside
    tarena-R1(config-if)#interface f0/1
    tarena-R1(config-if)#ip nat outside

5）分别在两台PC机上测试到外网主机的通信

PC1测试如下所示：

PC2测试如下所示：

6）在R1上查看NAT转换表

tarena-R1#show ip nat translations
    Pro Inside global Inside local Outside local Outside global
    icmp 61.159.62.129:2029192.168.1.1:2029 192.168.2.1:2029 192.168.2.1:2029
    icmp 61.159.62.129:2030192.168.1.1:2030 192.168.2.1:2030 192.168.2.1:2030
    icmp 61.159.62.129:2031192.168.1.1:2031 192.168.2.1:2031 192.168.2.1:2031
    icmp 61.159.62.129:2032192.168.1.1:2032 192.168.2.1:2032 192.168.2.1:2032
    icmp 61.159.62.129:2033192.168.1.1:2033 192.168.2.1:2033 192.168.2.1:2033
    icmp 61.159.62.129:2034192.168.1.1:2034 192.168.2.1:2034 192.168.2.1:2034
    icmp 61.159.62.129:2035192.168.1.1:2035 192.168.2.1:2035 192.168.2.1:2035

输出结果显示，所有的内网IP地址在访问外网前均被转换成了路由器端口的IP地址。

五、办公区Internet的访问

目标：

在R1配置PAT端口多路复用使企业内网192.168.1.0/24复用f0/1端口的IP，实现外部网络的访问。

方案：

网络拓扑如下图所示：

步骤：

步骤一：在SM1划分vlan2、vlan3、vlan4 并给SM1配置虚端口IP并开启路由功能，1-4接口开启trunk

1）创建vlan并设置管理IP，开启路由功能，并把相应的接口划分到vlan下

SM1 (config)ip routing
    SM1 (config)#vlan 2
    SM1 (config-vlan)#vlan 3
    SM1 (config-vlan)#vlan 4
    SM1 (config-vlan)#
    SM1 (config-vlan)#exit
    SM1 (config)#interface vlan 1
    SM1 (config-if)#ip address 192.168.1.254 255.255.255.0
    SM1 (config-if)#eixt
    SM1 (config-if)#no shutdown
    SM1 (config-if)#exit
    SM1 (config)#interface vlan 2
    SM1 (config-if)#ip address 192.168.2.254 255.255.255.0
    SM1 (config-if)#no shutdown
    SM1 (config-if)#exit
    SM1 (config)#interface vlan 3
    SM1 (config-if)#ip address 192.168.3.254 255.255.255.0
    SM1 (config-if)#no shutdown
    SM1 (config-if)#exit
    SM1 (config)#interface vlan 4
    SM1 (config-if)#ip address 192.168.4.254 255.255.255.0
    SM1 (config-if)#no shutdown
    sw2(config)#vlan 2
    sw2(config-vlan)#exit
    sw2(config)#interface fastEthernet 0/1
    sw2(config-if)#switchport access vlan 2
    sw3(config)#vlan 3
    sw3(config-vlan)#exit
    sw3(config)#interface fastEthernet 0/1
    sw3(config-if)#switchport access vlan 3
    sw4(config)#vlan 4
    sw4(config-vlan)#exit
    sw4(config)#interface fastEthernet 0/1
    sw4(config-if)#switchport access vlan 4

2）交换机之间所连接的接口开启trunk

SM1(config)#interface range f0/1 - 4
    SM1 (config-if-range)#switchport trunk encapsulation dot1q
    SM1 (config-if-range)#switchport mode trunk
    sw1(config)#interface fastEthernet 0/3
    sw1(config-if)#switchport mode trunk
    sw2(config)#interface fastEthernet 0/3
    sw2(config-if)#switchport mode trunk
    sw3(config)#interface fastEthernet 0/3
    sw3(config-if)#switchport mode trunk
    sw4(config)#interface fastEthernet 0/3
    sw4(config-if)#switchport mode trunk

3）测试vlan之间的连通性

PC>ipconfig
    FastEthernet0 Connection:(default port)
    Link-local IPv6 Address.........: FE80::290:21FF:FEC2:1A50
    IP Address......................: 192.168.1.1
    Subnet Mask.....................: 255.255.255.0
    Default Gateway.................: 192.168.1.254
    PC>ping 192.168.2.1
    Pinging 192.168.2.1 with 32 bytes of data:
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.2.1: bytes=32 time=1ms TTL=12
    Ping statistics for 192.168.2.1:
    Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms
    PC>ping 192.168.3.1
    Pinging 192.168.3.1 with 32 bytes of data:
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.3.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.3.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.3.1: bytes=32 time=1ms TTL=127
    Ping statistics for 192.168.3.1:
    Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms
    PC>ping 192.168.4.1
    Pinging 192.168.4.1 with 32 bytes of data:
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.2.1: bytes=32 time=0ms TTL=127
    Reply from 192.168.4.1: bytes=32 time=0ms TTL=127
    Ping statistics for 192.168.4.1:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

4）为SM1与路由器连接的接口和路由器配置IP并启用动态路由RIP协议.

SM1(config)#interface fastEthernet 0/5
    SM1(config-if)#no switchport
    SM1(config-if)#ip add 192.168.5.1 255.255.255.0
    SM1(config-if)#no shutdown
    SM1(config-if)#exit
    SM1(config)#router rip
    SM1(config-router)#version 2
    SM1(config-router)#no auto-summary
    SM1(config-router)#network 192.168.1.0
    SM1(config-router)#network 192.168.2.0
    SM1(config-router)#network 192.168.3.0
    SM1(config-router)#network 192.168.4.0
    SM1(config-router)#network 192.168.5.0
    Router(config)#interface fastEthernet 0/0
    Router(config-if)#ip address 192.168.5.2 255.255.255.0
    Router(config-if)#no shutdown
    Router(config-if)#exit
    Router(config)#interface fastEthernet 0/1
    Router(config-if)#ip address 61.159.62.129 255.255.255.248
    Router(config-if)#exit
    Router(config)#router rip
    Router(config-router)#version 2
    Router(config-router)#no auto-summary
    Router(config-router)#network 192.168.5.0

5）在路由器上配置默认路由并发布到RIP协议里并在三成交换机SM1上查看路由表

Router(config)#ip route 0.0.0.0 0.0.0.0 f0/1
Router(config)#router rip
Router(config-router)#default-information originate

SM路由表如下所示：

SM1# show ip route
    Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
    D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
    N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
    E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
    i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
    * - candidate default, U - per-user static route, o - ODR
    P - periodic downloaded static route
    Gateway of last resort is 192.168.5.2 to network 0.0.0.0
    C 192.168.1.0/24 is directly connected, Vlan1
    C 192.168.2.0/24 is directly connected, Vlan2
    C 192.168.3.0/24 is directly connected, Vlan3
    C 192.168.4.0/24 is directly connected, Vlan4
    C 192.168.5.0/24 is directly connected, FastEthernet0/5
    R* 0.0.0.0/0 [120/1] via 192.168.5.2, 00:00:18, FastEthernet0/5

6）在路由器上配置PAT

Router(config)#access-list 1 permit 192.168.4.0 0.0.0.255
    Router(config)#ip nat inside source list 1 interface f0/1
    Router(config)#interface fastEthernet 0/0
    Router(config-if)#ip nat inside
    Router(config-if)#exit
    Router(config)#interface fastEthernet 0/1
    Router(config-if)#ip nat outside

7）用192.168.4.0和192.168.1.0测试网络连通性

PC1

PC>ping 61.159.62.130
    Pinging 61.159.62.130 with 32 bytes of data:
    Request timed out.
    Request timed out.
    Request timed out.
    Request timed out.
    Ping statistics for 61.159.62.130:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

PC4

PC>ping 61.159.62.130
    Pinging 61.159.62.130 with 32 bytes of data:
    Reply from 61.159.62.130: bytes=32 time=0ms TTL=126
    Reply from 61.159.62.130: bytes=32 time=0ms TTL=126
    Reply from 61.159.62.130: bytes=32 time=0ms TTL=126
    Reply from 61.159.62.130: bytes=32 time=0ms TTL=126
    Ping statistics for 61.159.62.130:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

结果显示只有办公网可以访问Internet

码农公寓

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