NAT for IPv4

NAT for IPv4

1. Concept

   • It is used to preserve IPv4 addresses and provide privacy and security
     • NAT routers
       • They work in the border of a network of internal routes
         • Network of internal routes
           • It is the one that has a single connection to your neighbor network
             • What happens when a internal device wants communicate with the outside?
               • The packet is forwarded to the router of border. The border router performs the NAT process
                 • NAT process
                   • Translate the internal private address from the device to a public address

2. NAT terminology

   • Internal management
     • the address of the device that it is translated by means of NAT.
   • Address external
     • the address of target device.
   • Local address
     • any address that appears in the internal portion of the network.
   • Global address
     • any address that appears in the external portion of the network.

3. NAT types

   • Static NAT
     • One-to-one address assignment between a local address and a global one.
   • NAT dynamic
     • assignment of several addresses to several directions between local and global addresses
       • Translations are made in function of availability...
   • PAT
     • assignment of several addresses to one Address between local and global addresses
       • It is also known as "overload"
       • you can assign several directions to one or more addresses
         • each private address is also track with a port number

4. Advantages and disadvantages of NAT

   • Advantage
     • retains the addressing scheme legally registered by allowing the privatization of intranets
     • Keep the directions by multiplexing applications at the port level
     • increases the flexibility of connections to the public network
     • provides coherence to the schemes of internal network addressing
     • hides the IPv4 addresses of users.
   • Disadvantages
     • Performance is affected
     • Determine end-to-end functionality
     • Reduce IP tracking
     • The tunning becomes more delayed
     • The start of TCP connections can be interrupted

5. NAT for IPv6?

   • With a 128-bit address, IPv6 provides 340 sextillions of directions. Therefore, the Address space is not a problem
     • IPv6 was developed with the intention that NAT for IPv4 with its translation between addresses Public and private IPv4 is unnecessary
       • However, IPv6 implements a form of NAT
         • The objective of the ULA is to provide space of IPv6 addresses for communications within a local site