网络工程 - GNS3 nat 配置问题 - 吾爱随笔录

我正在为我的 CCENT 考试而学习，我正在尝试练习 NAT 的配置。

R1配置：

Building configuration...

Current configuration : 1211 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
!
!
ip cef
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
!
interface FastEthernet0/0
 ip address 192.168.100.1 255.255.255.0
 duplex auto
 speed auto
!
interface Serial1/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial1/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial1/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial1/3
 no ip address
 shutdown
 serial restart-delay 0
!
interface FastEthernet2/0
 ip address 200.2.2.2 255.255.255.0
 duplex auto
 speed auto
!
interface FastEthernet3/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 200.2.2.3
!
!
!
no cdp log mismatch duplex
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line vty 0 4
 login
!
!
end

R4配置：

Building configuration...

Current configuration : 845 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
!
!
ip cef
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
!
interface FastEthernet0/0
 ip address 200.2.2.3 255.255.255.0
 duplex auto
 speed auto
!
interface FastEthernet1/0
 ip address 200.2.0.1 255.255.255.0
 duplex auto
 speed auto
!
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 200.2.2.2
!
!
!
no cdp log mismatch duplex
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line vty 0 4
 login
!
!
end

我还没有设置NAT，但是PC3可以ping通PC1和PC2，你能解释一下为什么吗？我认为如果没有 NAT，私有 IP 将无法与公共通信。我应该创建什么配置才能练习 NAT？