Network Address Translation

Question 1

NAT (Network Address Translation)

Answer 1

• It is estimated that there are over 20 billion devices
connected to the Internet (and growing)
• IPv4 supports around 4.29 billion addresses

• The address space for IPv4 is exhausted
  
  • There are no available addresses to assign
• How does it all work?
  
  • Network Address Translation
• This isn’t the only use of NAT
  
  • NAT is handy in many situations

Question 2

Port Forwarding

Answer 2

• 24x7 access to a service hosted internally
  
  • Web server, gaming server, security system, etc.
• External IP/port number maps to an internal IP/port
  
  • Does not have to be the same port number

• Also called Destination NAT or Static NAT
• Destination address is translated
from a public IP to a private IP
• Does not expire or timeout

Question 3

RFC 1918 Private IPv4 Addresses

Answer 3

10. 0.0.0 – 10.255.255.255 single class A
11. 16.0.0 – 172.31.255.25516 class Bs
12. 168.0.0 – 192.168.255.255 class Cs

Question 4

NAT Overloading aka Port Address Translation

Answer 4

In PAT, Private IP addresses are translated into the public IP address via Port numbers. PAT also uses IPv4 address but with port number.