NAT

[M.Sultan]

Hi, 

Dynamic NAT

uses a pool of public ip address to perform

NAT

, One single interface can be assigned two IP addresses the first primary and the secondary, if we want to use 5 public ip addresses for

Dynamic NAT

where should we assign them ? while we have one single ISP link  ?

thank you

[MHM Cisco World]

can you more elaborate 

[paul driver]

Hello
you create a acces-list for you lan clients and a

NAT pool

for the 5 public ip address

example:

access-list 1 192.168.1.0 0.0.0.255
Ip nat pool PUBLIC 1.1.1.1 1.1.1.5 prefix 29
ip mat inside source list 1 pool PUBLIC overload

sent from iphone:

[M.Sultan]

At least i need on of public ip to be assigned into my inside global interface and the rest 4 publics won't need be added to interface ? just add them into the pool ???

[MHM Cisco World · Accepted solution]

correct, ONE IP assign to ip nat outside interface and other public IP is add to Pool of NAT

[paul driver]

Hello

@M.Sultan  wrote:

At least i need on of public ip to be assigned into my inside global interfac

---

---

@MHM Cisco World wrote:

correct, ONE IP assign to

ip nat

outside interface and other public IP is add to Pool of

NAT

---

FYI, the public

nat

addressing does NOT need to be assigned to any interface, they just need to be reachable to external users for your site

[M.Sultan]

A public IP must be assigned to the inside global interface and the rest four IP including assigned IP should be added to the scope of access list. 

Exm: Int 0/0 (1.1.1.1 255.0.0.0) 

ip nat pool Public 1.1.1.1 1.1.1.5 prefix 8

am i correct ?

[MHM Cisco World · Accepted solution]

interface ethernet 0
 ip address 10.10.10.1 255.255.255.0
 ip nat inside

!--- Defines Ethernet 0 with an IP address and as a NAT inside interface.


interface ethernet 1
 ip address 10.10.20.1 255.255.255.0
 ip nat inside

!--- Defines Ethernet 1 with an IP address and as a NAT inside interface.


interface serial 0
 ip address 172.16.10.64 255.255.255.0
 ip nat outside

!--- Defines serial 0 with an IP address and as a NAT outside interface.

 
ip nat pool no-overload 172.16.10.1 172.16.10.63 prefix 24


!--- Defines a NAT pool named no-overload with a range of addresses 
!--- 172.16.10.1 - 172.16.10.63.


ip nat inside source list 7 pool no-overload 


!--- Indicates that any packets received on the inside interface that 
!--- are permitted by access-list 7 has 
!--- the source address translated to an address out of the 
!--- NAT pool "no-overload".


access-list 7 permit 10.10.10.0 0.0.0.31
access-list 7 permit 10.10.20.0 0.0.0.31

!--- Access-list 7 permits packets with source addresses ranging from 
!--- 10.10.10.0 through 10.10.10.31 and 10.10.20.0 through 10.10.20.31.

 Configure Network Address Translation - Cisco

this link explain all cases need for NAT, one of them is using POOL