Analysis on the concept of vronat NAT

NAT concepts

NAT not only perfectly solves the problem of insufficient lP addresses, but also effectively avoids attacks from outside the network and hides and protects computers inside the network. Here are two terms:

Internal local address, inside local address: internal IP address, compared to 192. 168. *. *, 10 .*.*.*

Valid internal address: inside global address: public network, external IP address, such as 202. 190 .*.*

NAT Mode

1. Static address conversion.

Requirements:

One-to-one conversion between the Intranet address and the Internet address can completely map the port of the internal machine through an external ip address, or map the port one by one.

Steps:

1. Create a static ing between the Intranet address and the Internet address, and enter

Ip nat inside source static Intranet address Internet address

2. Specify the inner network port and enter it in the inner network port setting status.

Ip nat inside

3. Specify the Internet port, and enter

Ip nat outside

2. Dynamic address translation.

Requirements:

Dynamic Address Translation also performs one-to-one conversion between Intranet addresses and Internet addresses. However, dynamic address translation dynamically selects an unused address from the Internet IP address pool to convert Intranet addresses.

Steps:

1. Define an Internet address pool

Ip nat pool address pool name start ip address end ip address Subnet Mask

2. Define an access-list rule to specify which Intranet addresses are allowed for Dynamic Address Translation

Access-list label (1-99) permit source address wildcard

3. Convert the Intranet address and Internet address specified by access-list

Ip nat inside source list Access Control list number pool Internet address pool name

4. Execute the following on the Intranet interface:

Ip nat inside

5. Execute the following command on the outer network interface:

Ip nat outside

3. Reuse dynamic address translation.

Requirements:

Multiplexing dynamic address translation is also a kind of dynamic address translation, but it allows multiple Intranet addresses to share one Internet address. A computer is identified by using the tcp or udp port number in the vro.

Steps:

1. Define an Internet address pool

Ip nat pool address pool name start ip address end ip address Subnet Mask

2. Define an access-list rule to specify which Intranet addresses can be dynamically converted

Access-list label (1-99) permit source address wildcard

3. Set the Intranet address and Internet address to reuse Dynamic Address Translation

Ip nat inside source list access list No. The pool's internal legal address pool name overload

4. Execute ip nat inside on the Intranet Interface

5. Execute ip nat outside on the Outer Network Interface

The knowledge of NAT is introduced for everyone, this article briefly introduces the knowledge of NAT, if the readers want to learn more about the knowledge, please see the other introduction of this site: http://network.51cto.com/col/551/