NAT & PAT configuration on Cisco Packet tracer

Network Address Translation(NAT)

  •  NAT is a process of changing one IP into another.
  •  NAT is used to save Public IP.
  •  It provides security.

 In other words NAT converts request from Private IP address to Public IP address and vice-verse. It helps in hiding the Private IP address of an organization by representing Public IP address as a source/destination.

Types of NAT
  • STATIC NAT(one-one mapping)
  • DYNAMIC NAT(many-many mapping)
  • PAT(many-one mapping)

STATIC NAT:

  • One Private IP address is mapped to one Public IP address.
  • Generally used for hosting public servers.
  • Configured for inbound traffic.
STEPS FOR CONFIGURING STATIC NAT IN CISCO ROUTER:

ISPRouter(config)#interface serial 0/0
ISPRouter(config-if)#ip address 11.0.0.2 255.0.0.0
ISPRouter(config-if)#no shutdown
ISPRouter(config-if)#encapsulation ppp
ISPRouter(config-if)#clock rate 64000
ISPRouter(config-if)#exit

ISPRouter(config)#interface fast Ethernet 0/0
ISPRouter(config-if)#ip address 10.0.0.1 255.0.0.0
ISPRouter(config-if)#no shutdown
ISPRouter(config)#ip route 0.0.0.0 0.0.0.0 s0/0
ISPRouter(config)#ip nat inside source static 10.0.0.2 11.0.0.2
ISPRouter(config)#interface serial 0/0
ISPRouter(config-if)#ip nat outside
ISPRouter(config-if)#exit
ISPRouter(config)#internet fast Ethernet 0/0
ISPRouter(config-if)#ip nat inside
ISPRouter(config-if)#exit

Port Address Translation(PAT):

  • Many Private IP address are mapped to one Public IP address.
  • All users can access internet at the same time.
  • Only configured for outbound traffic.

STEPS FOR CONFIGURING PAT IN CISCO ROUTER:
MYRouter(config)#internet serial 0/0
MYRouter(config-if)#ip ad 11.0.0.1 255.0.0.0
MYRouter(config-if)#no shutdown
MYRouter(config-if)#encapsulation ppp
MYRouter(config)#ip route 0.0.0.0 0.0.0.0 s0/0
MYRouter(config)#access-list 1 permit 192.168.1.0 0.0.0.255
MYRouter(config)#ip nat inside source list 1 int s0/0 overload



Video for the above configuration
http://youtu.be/igGz_zqdXZ0

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