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NAT (Disadvantages of NAT (Degraded peformance (eg VOIP is affected, first…

- - - - automatically neccasary
      - allows multiple ports to translate to single "internal" port
- - - - ip nat inside source static local-ip global-ip
    - - ip nat inside
      - ip nat outside
  - - - when using verborse translation entires timeout after 24 hours
        
        can change with ip nat translation timeout timeouts-seconds
      - clear dynamic entires
        
        clear ip nat translations *
        
        other clear options avaliable
  - - - ip nat pool name start-ip end-ip {netmask netmask | prefx-length prefix-length}
    - - access-list access-list-number permit source [source wild-card]
    - - ip nat inside source list access-list-number pool name
    - - ip nat inside
      - ip nat outside
  - - - 2 Configure (stanard) access list - permits addresses that should be translated
        
        access-list access-list-number permit source [source wild-card]
      - Link access-list and pool - using keyword overload
        
        ip nat inside source list access-list-number pool name overload
      - Define pool of global addresses
        
        ip nat pool name start-ip end-ip {netmask netmask | prefx-length prefix-length}
      - Configure outside and inside interface
        
        ip nat inside
        
        ip nat outside
    - - Same as configuring for pool except the linking of pool and access-list
        
        No pool is configured
        
        interface keyword is used instead of pool in command
        
        ip nat inside source list access-list-number interface type number overload
      - Address of interface is used
- - - - source client ports always different
    - - used by PAT as identifier
      - other protocols used other identifiers
        
        eg ICMP query ID
      - creates a mapping between port number and inside local address
        
        adds a degree of validation and thus security
    - - PAT attempts to preserve original source port
      - As clients can use same source port number its possible for PAT to be dealing with the same port number
        
        next avaliable port number is used
      - once all ports assigned to ip address - nex avaliable IP address is used
- - - - not routable over the internet
      - not currently able to be translated to global unicast address
    - - FC00:: to FDFF::
  - - - Should run IPv6 natively wherever possible
    - - NAT64 is now recommended