Network Address Translation (NAT)
Network Address Translation (NAT) is a technique commonly used by Internet Service Providers (ISPs) and organizations to enable multiple devices to share a single public IP address. By using NAT, devices on a private network can communicate with devices on a public network without each device having its own unique IP address.
NAT became popular as a solution to the IPv4 address shortage to avoid the difficulty of reserving IP addresses. Web address translation is widely used in many countries. That's why NAT has become a standard feature of routers on home and small office network connections, for whom the cost of requesting a separate IP address outweighs the benefits.
IPv4 address
IPv4 uses 32-bit (4-byte) addresses, so there are only about four billion (4,294,967,296,232) addresses in the address space, which is about 4.3 billion.
Except for private networks, loopbacks, multicasts, and other reserved addresses,The ≈ of IPv4 addresses that can be routed over the public network is 3.6 billion ~ 3.7 billionindividuals
How NAT works
NAT is typically implemented on routers, which connect two network devices. When a device on a private network sends data to a device on the public network, the router intercepts the data and replaces the source IP address with its own public IP address. The router then sends the data to the target device.
When the target device sends data back to the router, the router intercepts it and replaces the public IP address with the original source IP address. The router then sends the data to the original source device. This process is transparent to devices on both networks.
Network address translation offers several significant advantages:
IP address protection: By enabling multiple devices to share a single IP address, NAT helps save IP address space. This is especially important for organizations where ISPs have assigned a limited number of IP addresses.
Improved security: NAT can provide security measures by hiding the internal network from the outside world. This is useful for preventing attacks targeting specific IP addresses or preventing devices on internal networks from accessing directly from the internet. NAT can also help prevent devices on your internal network from accessing malicious or unwanted websites.
Faster speeds: NAT can improve communication speeds by reducing the number of packets that need to be routed through the network. This is because NAT eliminates the need for each device on the internal network to have its own unique IP address.
Flexibility: NAT can also be used to provide flexibility in network design, which can be especially useful for organizations that want to change their network configuration without changing their IP address. Organizations may want to change their network configuration to improve security or performance, or to add new devices to the network.
Multihomed: NAT can be used to allow devices on a private network to connect to multiple public networks, a network configuration practice known as multihomed. This can be valuable for organizations that want to connect to multiple ISPs or who want to provide failover if one of them fails. NAT multihomed provides connection redundancy and increases uptime by allowing traffic to route through multiple ISPs.
Cost savings: NAT reduces the number of IP addresses required by an organization, saving on IP address licenses and other associated fees.
Easier Network Management: NAT makes network management easier by reducing the number of IP addresses that need to be assigned. This benefits organizations with a large number of devices, as well as those looking to reduce the time and effort required to manage their networks.
Types of Network Address Translation (NAT).
There are three types of network address translation:
Static NAT
In static NAT, each internal IP address is mapped to a unique external IP address. This is a one-to-one mapping. When outgoing traffic reaches the router, the router replaces the destination IP address with a mapped global IP. When the return traffic returns to the router, the router replaces the mapped global IP address with the source IP address.
Static NAT is primarily used for servers that need access from the internet, such as web servers and email servers.
Dynamic NAT
In dynamic network address translation, internal IP addresses are mapped to external IP address pools. This is a one-to-many mapping. When outgoing traffic reaches the router, the router replaces the destination IP address with a free global IP address from the pool. When the return traffic returns to the router, the router replaces the mapped global IP address with the source IP address.
Dynamic NAT is primarily used in networks that require an outbound internet connection.
Port Address Translation (PAT)
PAT is a dynamic NAT that maps multiple internal IP addresses to a single external IP address by port number. This is a many-to-one mapping. When a computer connects to the internet, the router assigns it a port number and then attaches it to the computer's internal IP address, giving the computer a unique IP address. When the second computer connects to the internet, it gets the same external IP address but with a different port number.
PAT is primarily used in home networks. |
Posted on 2025-11-28 11:46:04
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Landlord|
Posted on 2025-11-28 11:46:36
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