PAT端口多路復(fù)用(實踐)

拓撲結(jié)構(gòu)圖

第一步:配置交換機SW

sw#conf t
sw(config)#no ip routing            //關(guān)閉路由功能
sw(config)#int f1/0 
sw(config-if)#speed 100             //配置速率
sw(config-if)#dup full              //配置全雙工模式
sw(config-if)#ex

第二步:配置路由器R1,并設(shè)定PAT

R1#conf t
R1(config)#int f0/0
R1(config-if)#ip add 192.168.100.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#int f0/1
R1(config-if)#ip add 12.0.0.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#ex
R1(config)#access-list 1 permit 192.168.100.0 0.0.0.255
//定義內(nèi)部訪問列表
R1(config)#ip nat inside source list 1 interface fastEthernet 0/1 overload 
//設(shè)置復(fù)用動態(tài)IP地址轉(zhuǎn)換于外部接口
R1(config)#int f0/0
R1(config-if)#ip nat inside     
R1(config-if)#int f0/1
R1(config-if)#ip nat outside
R1(config-if)#end

第三步:配置客戶機IP地址

PC1> ip 192.168.100.10 192.168.100.1
Checking for duplicate address...
PC1 : 192.168.100.10 255.255.255.0 gateway 192.168.100.1

PC2> ip 192.168.100.20 192.168.100.1
Checking for duplicate address...
PC1 : 192.168.100.20 255.255.255.0 gateway 192.168.100.1

PC3> ip 12.0.0.12 12.0.0.1
Checking for duplicate address...
PC1 : 12.0.0.12 255.255.255.0 gateway 12.0.0.1

第四步:測試全網(wǎng)互通,并使用debug 功能查看PAT過程

PC1> ping 12.0.0.12
84 bytes from 12.0.0.12 icmp_seq=1 ttl=63 time=31.242 ms
84 bytes from 12.0.0.12 icmp_seq=2 ttl=63 time=46.864 ms
84 bytes from 12.0.0.12 icmp_seq=3 ttl=63 time=31.280 ms
84 bytes from 12.0.0.12 icmp_seq=4 ttl=63 time=31.241 ms
84 bytes from 12.0.0.12 icmp_seq=5 ttl=63 time=31.241 ms

R1#debug ip nat
IP NAT debugging is on
R1#
*Mar  1 00:32:57.215: NAT*: s=192.168.100.10->12.0.0.1, d=12.0.0.12 [59174]
*Mar  1 00:32:57.219: NAT*: s=12.0.0.12, d=12.0.0.1->192.168.100.10 [59174]
...
//私網(wǎng)地址192.168.100.10已轉(zhuǎn)換成功公網(wǎng)地址12.0.0.1,并接收到來自公網(wǎng)主機的回復(fù)信息

PC2> ping 12.0.0.12
84 bytes from 12.0.0.12 icmp_seq=1 ttl=63 time=31.242 ms
84 bytes from 12.0.0.12 icmp_seq=2 ttl=63 time=31.245 ms
84 bytes from 12.0.0.12 icmp_seq=3 ttl=63 time=31.244 ms
84 bytes from 12.0.0.12 icmp_seq=4 ttl=63 time=31.213 ms
84 bytes from 12.0.0.12 icmp_seq=5 ttl=63 time=31.246 ms

R1#
*Mar  1 00:35:15.595: NAT*: s=192.168.100.20->12.0.0.1, d=12.0.0.12 [59312]
*Mar  1 00:35:15.607: NAT*: s=12.0.0.12, d=12.0.0.1->192.168.100.20 [59312]
...
////私網(wǎng)地址192.168.100.20已轉(zhuǎn)換成功公網(wǎng)地址12.0.0.1,并接收到來自公網(wǎng)主機的回復(fù)信息

小結(jié)

PAT存在的意義

1.動靜態(tài)NAT無法解決ip地址匱乏問題 (默認一個私網(wǎng)IP地址對一個公網(wǎng)IP地址)
2.PAT卻可以解決ip地址匱乏(多個私網(wǎng)IP地址對一個公網(wǎng)IP地址)