Learn about NAT (Last part)

In the previous sections, Network Administrator introduced you to the configuration and operation mechanism of NAT (Network Address Translation) as well as the operation mechanism of NAT (Dynamic NAT) and Overloading NAT . The Network Administrator will introduce you to security issues and the multiple network connection mechanism of NAT .

1. Security and network administration issues

Dynamic NAT ( dynamic NAT ) automatically creates a firewall between internal and external networks, or between your internal networks and the Internet. NAT only allows connections originating within Stub Domain .

Basically, this means that a computer located on an external network cannot connect to your computer, unless your computer is connected to that computer first.

You can browse the Internet and connect to a website, or even download a file; but others cannot use your IP addresses to connect to a port on your computer.

In specific cases, Static NAT (static NAT) also allows external devices to initiate connections to computers on Stub Domain.

For example, if you want to go from the Inside Global Address address to a specific Local Local Address address assigned to your Web server, Static NAT (static NAT) will allow connection.

Some NAT Routers provide filters and traffic logging . Filters allow your company to control which pages visitors visit on the Web to prevent them from viewing important documents. You can use traffic logging to create a log file of visited websites and create different reports.

NAT is sometimes mistaken for proxy servers, but there are certain differences between NAT and proxy servers.

NAT cannot be confused with source computers and destination computers. No one can recognize NAT as a third device.

A proxy server may be confused. The source computer knows that it makes a request to the proxy server and must be configured to make that request. The destination computer will understand that the proxy server is the source computer, and deal with it directly.

In addition, the proxy server usually works on the 4th floor (Transport) in the OSI Reference Model or higher, while NAT works on the 3rd layer of the network protocol (Network protocol) . Working at a higher level makes proxy servers slower than NAT devices.

The biggest benefit of NAT is that network administration ( Network Administation) is clear. For example, you can move your Web server or FTP server to another host computer without worrying about broken links.

Simply change, use Inbound Route Map to respond to the new server. You can also change the internal network (Internal Network) easily, because only the external IP address or IP address of the Router or IP address in the Global Address group .

NAT and DHCP (dynamic host configuration protocol - dynamic Host configuration protocol ). You can select a range of Private IP addresses on the Stub Domain and have a DHCP server play these IP addresses when needed.

You do not need to request multiple IP addresses from IANA. Instead, you can only increase the range of IP addresses available in DHCP configuration to immediately add IP addresses on your networked computer.

2. Multi-homing connection

Large businesses or companies need to use the Internet more. Therefore, establishing an Internet connection point becomes an integral part of their network strategy. Multiple network connections (or multiple connections), called multi-homing.

In addition to maintaining a reliable, multi- network connection (multi-homing) that allows your company or business to load-balancing by reducing the number of computers connected to the Internet through Any one single connection. Distribute load (Distributing the load) through multiple performance optimization connections and can significantly reduce waiting time.
Multi-homed connections are often connected to different ISPs ( Internet Service Providers - Internet service providers). Each ISP assigns an IP address (or range of IP addresses) to your company or business.

Routers use BGP (Border Gateway Protocol) , part of the TCP / IP protocol , to route between networks using different protocols. In a multi-homed network, the router uses Internal Border Gateway Protocol (IBGP) in S tub Domain , and EBGP (External Border Gateway Protocol) to communicate with other routers .

Multi-homing will make a difference if one of the connections to the ISP is broken. As soon as the router is assigned to connect to the ISP to determine that the connection is corrupted, the router will reroute all data through one of the other routers .

NAT can be used to extend routing for multi-homed , providing more connections.

Explore more:

1. Learn about the mechanism of NAT (Network Address Translation) (Part 1)

2. Learn about NAT configuration (part 2)

3. How does Dynamic NAT (dynamic NAT) and Overloading NAT work? (Part 3)

Having fun!