cisco的PAT

PAT所解决的问题和NAT一样，只不过处理方法不同，NAT是直接改的IP，而PAT则是将IP后附带端口信息，以此来增加访问网络的数量。

思路整理：
1、有访问控制列表
2、在设置PAT规则
3、设置端口的进和出的数据流向

一、网络拓扑图

二、设置端口的IP

R1路由器 左

Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#int f0/1
Router(config-if)#ip add 192.168.1.254 255.255.255.0
Router(config-if)#no shutdown 
Router(config-if)#int f0/0
Router(config-if)#ip addr 192.168.4.254 255.255.255.0
Router(config-if)#no shutdown
%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Router(config-if)#int s0/0/0
Router(config-if)#ip add 10.1.1.1 255.255.255.0
Router(config-if)#no shutd
Router(config-if)#no shutdown 

%LINK-5-CHANGED: Interface Serial0/0/0, changed state to down
Router(config-if)#clock rate 64000

R2 路由器 右

也是设置端口IP，就不复制了吧。。。。。。QAQ

三、设置PAT
R1 路由

Router(config)#access-list 1 permit 192.168.1.0 0.0.0.255
Router(config)#access-list 1 permit 192.168.4.0 0.0.0.255

Router(config)#ip nat inside source list 1 interface s0/0/0 overload 

Router(config)#int f0/0
Router(config-if)#ip na
Router(config-if)#ip nat inside 
Router(config-if)#int f0/1
Router(config-if)#ip nat inside 
Router(config-if)#int s0/0/0
Router(config-if)#ip nat outside 

Router(config)#ip route 192.168.2.0 255.255.255.0 10.1.1.2

四、测试

能够ping通

查看转化表有内容。

Router#show ip nat translations 
Pro  Inside global     Inside local       Outside local      Outside global
icmp 10.1.1.1:1        192.168.1.2:1      192.168.2.1:1      192.168.2.1:1
icmp 10.1.1.1:2        192.168.1.2:2      192.168.2.1:2      192.168.2.1:2
icmp 10.1.1.1:3        192.168.1.2:3      192.168.2.1:3      192.168.2.1:3
icmp 10.1.1.1:4        192.168.1.2:4      192.168.2.1:4      192.168.2.1:4

但是这时并没有路由表：

R1 路由表：

Router#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, Serial0/0/0
C    192.168.1.0/24 is directly connected, FastEthernet0/1
S    192.168.2.0/24 [1/0] via 10.1.1.2
C    192.168.4.0/24 is directly connected, FastEthernet0/0

R2 路由表

Router#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, Serial0/0/0
C    192.168.2.0/24 is directly connected, FastEthernet0/1

这时可以看到R2 路由并没有设置路由表，但是依旧能够ping通，这是因为PAT的设置之后，从10.1.1.1端口出去的主机都会变成10.1.1.0这个网络的。192.168.1.0转化为10.1.1.0，而10.1.1.0在R2 路由表上，是直连网络，所以能够正常ping通。