Configuring and Verifying NAT on CISCO Routers

Network Address Translation (NAT)
private IP address -> Public IP address



How to Configure Static NAT
============================
R1#conf t
R1(config)#ip nat inside source static 192.168.1.2 2.1.1.1
R1(config)#ip nat inside source static 192.168.1.3 2.1.1.2
R1(config)#ip nat inside source static 192.168.1.4 2.1.1.3

Verify the NAT Table Created
============================
R1#show ip nat translations

Applying Static NAT
====================

R1(config)#interface fa0/0
R1(config-if)#ip nat inside

R1(config)#interface fa0/1
R1(config-if)#ip nat outside



Configuring Dunamic NAT
=================================

1. Configure access list to define those who
   should be NATTED
===============================================
R1#conf t
R1(config)#access-list 20 permit 192.168.1.0 0.0.0.255

2. Create a Pool which will be used by the Internal
   PC.
====================================================
R1(config)#ip nat pool INTERNET_POOL 16.0.0.1 16.0.0.50 netmask 255.0.0.0

3. Create a NAT statement which will combine the 2 above statements
====================================================================
R1(config)#ip nat inside source list 20 pool INTERNET_POOL

===================================================================

Configure PAT to use an IP address from the outside interface
==============================================================


1. Configure access list to define those who
   should be NATTED
===============================================
R1#conf t
R1(config)#access-list 20 permit 192.168.1.0 0.0.0.255


2. Create the PAT Statement
==============================

R1(config)#ip nat inside source list 20 interface fa0/1 overload


3. Apply the NAT statement
=========================
R1(config)#interface fa0/0
R1(config-if)#ip nat inside

R1(config)#interface fa0/1
R1(config-if)#ip nat outside

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