Network Address Translation (Nat) Is Typically Implemented With Which Hardware Devices?

To access the Net, ane public IP accost is needed, but we tin can use a individual IP address in our private network. The idea of NAT is to allow multiple devices to access the Net through a single public address. To attain this, the translation of a individual IP address to a public IP address is required. Network Address Translation (NAT) is a process in which ane or more local IP address is translated into ane or more Global IP address and vice versa in order to provide Internet access to the local hosts. Also, it does the translation of port numbers i.east. masks the port number of the host with some other port number, in the packet that will be routed to the destination. It then makes the respective entries of IP address and port number in the NAT tabular array. NAT more often than not operates on a router or firewall.

Network Address Translation (NAT) working –
Generally, the edge router is configured for NAT i.e the router which has one interface in the local (inside) network and one interface in the global (exterior) network. When a packet traverse outside the local (inside) network, then NAT converts that local (individual) IP accost to a global (public) IP accost. When a package enters the local network, the global (public) IP address is converted to a local (private) IP address.

If NAT runs out of addresses, i.e., no address is left in the pool configured then the packets will exist dropped and an Internet Control Message Protocol (ICMP) host unreachable parcel to the destination is sent.

Why mask port numbers ?
Suppose, in a network, ii hosts A and B are connected. Now, both of them request for the same destination, on the same port number, say 1000, on the host side, at the same fourth dimension. If NAT does only translation of IP addresses, then when their packets will arrive at the NAT, both of their IP addresses would be masked by the public IP address of the network and sent to the destination. Destination will send replies to the public IP address of the router. Thus, on receiving a reply, it will be unclear to NAT as to which reply belongs to which host (because source port numbers for both A and B are the aforementioned). Hence, to avert such a problem, NAT masks the source port number besides and makes an entry in the NAT table.

NAT inside and outside addresses –
Within refers to the addresses which must be translated. Outside refers to the addresses which are not in control of an organization. These are the network Addresses in which the translation of the addresses will be washed.

• Inside local address – An IP address that is assigned to a host on the Within (local) network. The address is probably not an IP address assigned past the service provider i.e., these are private IP addresses. This is the inside host seen from the inside network.
  
• Inside global address – IP accost that represents ane or more inside local IP addresses to the outside world. This is the within host as seen from the outside network.
  
• Exterior local address – This is the actual IP address of the destination host in the local network afterwards translation.
  
• Exterior global address – This is the outside host equally seen from the exterior network. It is the IP address of the outside destination host before translation.
  

Network Address Translation (NAT) Types –
There are three means to configure NAT:

1. Static NAT – In this, a single unregistered (Private) IP address is mapped with a legally registered (Public) IP address i.e 1-to-one mapping betwixt local and global addresses. This is mostly used for Web hosting. These are not used in organizations equally there are many devices that will need Cyberspace access and to provide Net access, a public IP address is needed.

   Suppose, if at that place are 3000 devices that need admission to the Net, the system has to buy 3000 public addresses that will be very costly.
   

2. Dynamic NAT – In this type of NAT, an unregistered IP address is translated into a registered (Public) IP address from a pool of public IP addresses. If the IP address of the pool is not free, and then the packet will be dropped equally only a stock-still number of private IP addresses can exist translated to public addresses.

   Suppose, if there is a pool of 2 public IP addresses then only two private IP addresses can be translated at a given time. If 3rd private IP address wants to admission the Internet then the packet will be dropped therefore many private IP addresses are mapped to a pool of public IP addresses. NAT is used when the number of users who want to access the Internet is fixed. This is likewise very costly as the system has to buy many global IP addresses to make a pool.
   

3. Port Address Translation (PAT) – This is also known equally NAT overload. In this, many local (private) IP addresses can exist translated to a single registered IP address. Port numbers are used to distinguish the traffic i.e., which traffic belongs to which IP accost. This is most oftentimes used as it is cost-effective as thousands of users can exist connected to the Cyberspace by using just one real global (public) IP address.
   

Advantages of NAT –

• NAT conserves legally registered IP addresses.
  
• Information technology provides privacy every bit the device'due south IP address, sending and receiving the traffic, will be hidden.
  
• Eliminates address renumbering when a network evolves.
  

Disadvantage of NAT –

• Translation results in switching path delays.
  
• Certain applications will not part while NAT is enabled.
  
• Complicates tunneling protocols such as IPsec.
  
• Also, the router beingness a network layer device, should not tamper with port numbers(transport layer) simply it has to practise and so because of NAT.
  

Share this post