NAT

NAT Overload (PAT):
  most common form of NAT.  for outbound access.
  internal IP addresses rewritten as the one external public IP address
     with source port reassigned at router as needed to be unique

Static NAT:
  map public IP address to internal address of server.
  for inbound access.  
  the public address doesn't have to be assigned to an interface.
  different server ports can be rewritten to different servers.

Dynamic NAT: 
  IP address one-to-one.
  uncommon: merged organizations' overlapping IP addresses
      DNS reply rewritten to indicate other net


Dynamic NAT: 
1. Label interface as inside or outside:
(config-if)# ip nat inside|outside

2. Identify internal addresses to be translated:
(config)# ip access-list standard NAME
(config-std_nacl)# permit|deny    etc.

3. Enable NAT overload:
(config)# ip nat  inside  source list NAME  interface INT  overload

show ip nat translations


Static NAT:
ip nat inside source static IP_LOCAL IP_GLOBAL
Static port:  port forwarding?
ip nat inside source static tcp|udp IP_LOCAL PORT   INT PORT