Network address translation (NAT)

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Network Address Translation (NAT)

• Presented By
• Bishwas ghale
• Bsc NT
• 4th Semester
• Submitted To

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CONTENTS

• What is Network Address Translation ?
• Why Need Network Address Translation ?
• Brief Overview Network Address Translation
• Types of NAT
• NAT-
• -Benefits
• -Limitations
• Configuration of NAT

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What is Network Address Translation?

• It is the process of changing of Address
  Information in IP Headers while IP packets are in
  transit through a router
• Method of mapping an Internal IP Address Space to
  External IP Address Space

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Why Need Network Address Translation ?

• IPV4 address space is limited
• Internet gateways that use NAT are often used in
  homes and small offices.
• A user will have multiple devices to connect to
  internet
• NAT are used because they are cheap, easy to
  manage, and don't require users to install
  special software.

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Brief Overview Network Address Translation

• Outside local address - The local IP address
  assigned to a host on the outside network. In
  most situations, this address will be identical
  to the outside global address of that outside
  device.

• Inside local address - Usually not an IP address
  assigned by a RIR (Regional Internet Registries
  )or service provider and is most likely an RFC
  1918 private address. In the figure, the IP
  address 192.168.10.10 is assigned to the host PC1
  on the inside network.
• Inside global address - Valid public address that
  the inside host is given when it exits the NAT
  router. When traffic from PC1 is destined for the
  web server at 209.165.201.1, router R2 must
  translate the address. In this case, IP address
  209.165.200.226 is used as the inside global
  address for PC1.
• Outside global address - Reachable IP address
  assigned to a host on the Internet. For example,
  the web server is reachable at IP address
  209.165.201.1.

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Types of NAT

• Static
• Static NAT uses a one-to-one mapping of local to
  global ip addresses, and these mappings remain
  constant. Static NAT is particularly useful for
  web servers or hosts that must have a consistent
  address that is accessible from the Internet.
  Static Network Address Translation RFC 2663 .

• Dynamic
• Dynamic NAT uses a one-to-many mapping of local
  to global ip addresses. When a host with a
  private IP address requests access to the
  Internet, dynamic NAT chooses an IP address from
  the pool that is not already in use by another
  host. This is the mapping described so far. More
  complex configurations are also possible in
  dynamic NAT.

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NAT

• Benefits

• Limitations

• Conserves the legally registered addressing
  scheme
• Increases the flexibility of connections to the
  public network
• Provides consistency for internal network
  addressing schemes.
• Provides network security

• Performance is degraded
• End-to-end functionality is degraded
• End-to-end IP traceability is lost
• Tunneling is more complicated
• Initiating TCP connections can be disrupted
• Architectures need to be rebuilt to accommodate
  changes

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Configuration of NAT
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