Packet Tracer 5.2实验(十四) 网络地址转换NAT配置

一、实验目标

• 理解NAT网络地址转换的原理及功能；
• 掌握静态NAT的配置，实现局域网访问互联网；

二、实验背景

公司欲发布WWW服务，现要求将内网Web服务器IP地址映射为全局IP地址，实现外部网络可访问公司内部Web服务器。

三、技术原理

• 网络地址转换NAT（Network Address Translation），被广泛应用于各种类型Internet接入方式和各种类型的网络中。原因很简单，NAT不仅完美解决了IP地址不足的问题，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。
• 默认情况下，内部IP地址是无法被路由到外网的，内部主机10.1.1.1要与外部internet通信，IP包到达NAT路由器时，IP包头的源地址10.1.1.1被替换成一个合法的外网IP，并在NAT转换表中保存这条记录。当外部主机发送一个应答到内网时，NAT路由器收到后，查看当前NAT转换表，用10.1.1.1替换掉这个外网地址。
• NAT将网络划分为内部网络和外部网络两部分，局域网主机利用NAT访问网络时，是将局域网内部的本地地址转换为全局地址（互联网合法的IP地址）后转发数据包。
• NAT分为两种类型：NAT（网络地址转换）和NAPT（网络端口地址转换IP地址对应一个全局地址）。
• 静态NAT：实现内部地址与外部地址一对一的映射。现实中，一般都用于服务器；
• 动态NAT：定义一个地址池，自动映射，也是一对一的。现实中，用得比较少；
• NAPT：使用不同的端口来映射多个内网IP地址到一个指定的外网IP地址，多对一。

四、实验步骤

实验拓扑

1、R1为公司出口路由器，其与外部路由之间通过V.35电缆串口连接，DCE端连接在R2上，配置其时钟频率为64000；

2、配置PC机、服务器及路由器接口IP地址；

3、在各路由器上配置静态路由协议，让PC间能相互ping通；

4、在R1上配置静态NAT；

5、在R1上定义内外部网络接口；

6、验证主机之间的互通性。

R1:

Router>en
Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname R1
R1(config)#int fa0/0
R1(config-if)#ip add 192.168.1.1 255.255.255.0
R1(config-if)#no shut

%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
R1(config-if)#exit
R1(config)#int s2/0
R1(config-if)#ip add 222.0.1.1 255.255.255.0
R1(config-if)#no shut

%LINK-5-CHANGED: Interface Serial2/0, changed state to down
R1(config-if)#
%LINK-5-CHANGED: Interface Serial2/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0, changed state to up
R1(config-if)#
R1(config-if)#
R1(config-if)#exit
R1(config)#ip route 222.0.2.0 255.255.255.0 222.0.1.2                       //配置到222.0.2.0网段的静态路由
R1(config)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#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 not set

C    192.168.1.0/24 is directly connected, FastEthernet0/0
C    222.0.1.0/24 is directly connected, Serial2/0
S    222.0.2.0/24 [1/0] via 222.0.1.2
R1#
R1#
R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#int fa0/0
R1(config-if)#?
  arp                Set arp type (arpa, probe, snap) or timeout
  bandwidth          Set bandwidth informational parameter
  cdp                CDP interface subcommands
  crypto             Encryption/Decryption commands
  custom-queue-list  Assign a custom queue list to an interface
  delay              Specify interface throughput delay
  description        Interface specific description
  duplex             Configure duplex operation.
  exit               Exit from interface configuration mode
  fair-queue         Enable Fair Queuing on an Interface
  hold-queue         Set hold queue depth
  ip                 Interface Internet Protocol config commands
  mac-address        Manually set interface MAC address
  mtu                Set the interface Maximum Transmission Unit (MTU)
  no                 Negate a command or set its defaults
  priority-group     Assign a priority group to an interface
  service-policy     Configure QoS Service Policy
  shutdown           Shutdown the selected interface
  speed              Configure speed operation.
  tx-ring-limit      Configure PA level transmit ring limit
  zone-member        Apply zone name
R1(config-if)#ip ?
  access-group        Specify access control for packets
  address             Set the IP address of an interface
  hello-interval      Configures IP-EIGRP hello interval
  helper-address      Specify a destination address for UDP broadcasts
  inspect             Apply inspect name
  ips                 Create IPS rule
  mtu                 Set IP Maximum Transmission Unit
  nat                 NAT interface commands
  ospf                OSPF interface commands
  split-horizon       Perform split horizon
  summary-address     Perform address summarization
  virtual-reassembly  Virtual Reassembly
R1(config-if)#ip nat ?
  inside   Inside interface for address translation
  outside  Outside interface for address translation
R1(config-if)#ip nat inside ?
  <cr>
R1(config-if)#ip nat inside 
R1(config-if)#exit
R1(config)#int s2/0
R1(config-if)#ip nat outside ?
  <cr>
R1(config-if)#ip nat outside 
R1(config-if)#exit
R1(config)#
R1#
R1#
R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#ip ?
  access-list       Named access-list
  default-network   Flags networks as candidates for default routes
  dhcp              Configure DHCP server and relay parameters
  domain            IP DNS Resolver
  domain-lookup     Enable IP Domain Name System hostname translation
  domain-name       Define the default domain name
  forward-protocol  Controls forwarding of physical and directed IP broadcasts
  host              Add an entry to the ip hostname table
  name-server       Specify address of name server to use
  nat               NAT configuration commands
  route             Establish static routes
  tcp               Global TCP parameters
R1(config)#ip nat ?
  inside   Inside address translation
  outside  Outside address translation
  pool     Define pool of addresses
R1(config)#ip nat inside ?
  source  Source address translation
R1(config)#ip nat inside source ?
  list    Specify access list describing local addresses
  static  Specify static local->global mapping
R1(config)#ip nat inside source static ?
  A.B.C.D  Inside local IP address
  tcp      Transmission Control Protocol
  udp      User Datagram Protocol
R1(config)#ip nat inside source static 192.168.1.2 ?
  A.B.C.D  Inside global IP address
R1(config)#ip nat inside source static 192.168.1.2 222.0.1.3 ?
  <cr>
R1(config)#ip nat inside source static 192.168.1.2 222.0.1.3                //配置内网到外网的静态NAT映射
R1(config)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#show ip nat ?
  statistics    Translation statistics
  translations  Translation entries
R1#show ip nat translations 
Pro  Inside global     Inside local       Outside local      Outside global
---  222.0.1.3         192.168.1.2        ---                ---

R1#
R1#show ip nat translations 
Pro  Inside global     Inside local       Outside local      Outside global
---  222.0.1.3         192.168.1.2        ---                ---
tcp 222.0.1.3:80       192.168.1.2:80     222.0.2.2:1025     222.0.2.2:1025

R1#
R1#show running-config 
Building configuration...

Current configuration : 753 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R1
!
...
!
interface FastEthernet0/0
 ip address 192.168.1.1 255.255.255.0
 ip nat inside
 duplex auto
 speed auto
!
interface FastEthernet1/0
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface Serial2/0
 ip address 222.0.1.1 255.255.255.0
 ip nat outside
!
interface Serial3/0
 no ip address
 shutdown
!
interface FastEthernet4/0
 no ip address
 shutdown
!
interface FastEthernet5/0
 no ip address
 shutdown
!
ip nat inside source static 192.168.1.2 222.0.1.3 
ip classless
ip route 222.0.2.0 255.255.255.0 222.0.1.2 
!
...
!
line con 0
line vty 0 4
 login
!
!
!
end


R1#

R2:

Router>
Router>en
Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname R2
R2(config)#int fa0/0
R2(config-if)#ip add 222.0.2.1 255.255.255.0
R2(config-if)#no shut

%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
R2(config-if)#exit
R2(config)#int s2/0
R2(config-if)#ip add 222.0.1.2 255.255.255.0
R2(config-if)#no shut

%LINK-5-CHANGED: Interface Serial2/0, changed state to up
R2(config-if)#clock rate 64000
R2(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0, changed state to up
R2(config-if)#
R2(config-if)#
R2(config-if)#exit
R2(config)#ip route 192.168.1.0 255.255.255.0 222.0.1.1
R2(config)#end
R2#
%SYS-5-CONFIG_I: Configured from console by console
R2#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 not set

S    192.168.1.0/24 [1/0] via 222.0.1.1
C    222.0.1.0/24 is directly connected, Serial2/0
C    222.0.2.0/24 is directly connected, FastEthernet0/0
R2#

PC1:

Packet Tracer PC Command Line 1.0
PC>ipconfig

IP Address......................: 222.0.2.2
Subnet Mask.....................: 255.255.255.0
Default Gateway.................: 222.0.2.1

PC>ping 192.168.1.2

Pinging 192.168.1.2 with 32 bytes of data:

Request timed out.
Reply from 192.168.1.2: bytes=32 time=19ms TTL=126
Reply from 192.168.1.2: bytes=32 time=17ms TTL=126
Reply from 192.168.1.2: bytes=32 time=15ms TTL=126

Ping statistics for 192.168.1.2:
    Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
    Minimum = 15ms, Maximum = 19ms, Average = 17ms

PC>

PC1-WEB：