KR20030026740A - Method for network address transaction processing using the media access control - Google Patents

Abstract

PURPOSE: A network address translation processing method using a media access control is provided to suit a plurality of PCs(Personal Computer) sharing one IP to connect to the outside. CONSTITUTION: When processing a packet outgoing from a private network to an external network, a process is performed whether an MAC(Media Access Control) and an IP(Internet Protocol) address exist in an NAT(Network Address Translation) table(S11). A source address of an IP header is changed into a global IP address(S12). A corresponding packet is transmitted to the changed global IP address(destination). When processing a packet incoming from the external network to the private network, a private IP address corresponding to the MAC address of an incoming packet is tracked with reference to a table(S21). The destination address of header of the IP is changed into the searched corresponding private IP address with reference to the NAT table(S22). The packet is transmitted to the changed private IP address(S23).

Description

Process of network address translation using media access control {METHOD FOR NETWORK ADDRESS TRANSACTION PROCESSING USING THE MEDIA ACCESS CONTROL}

The present invention relates to a NAT processing method using a MAC address that implements a network address translation (NAT) function using a medium access control (MAC) address.

Network Address Translation (NAT) is a function that converts individual addresses and private IP addresses of a private network to each other. By this function, it is possible to access a global network such as the Internet even from a node to which an individual address is not assigned. . NAT uses a specific TCP / IP application by translating the communication protocol of the transport layer or application layer of TCP / IP for this purpose, and can identify only the source address and the IP address in the packet header. The correspondence between addresses and IP addresses is always 1: 1.

1 is a diagram illustrating a conventional NAT processing method, illustrating a connection process between a private network and a global network in a router. The first step S1 is a process of converting an IP address and a TCP port and transmitting the data. The first step S1 receives data from each port and converts the IP address and the TCP port according to a NAT mapping rule. The second step (S2) is a process of responding to the interface MAC address, and receives an ARP (Address Resolution Protocol) request packet from the host of the destination and responds to the interface MAC address of its own global network. The third step (S3) is a process of establishing communication between hosts. The destination host converts the received packet to the reverse host and transmits the received packet to the private network host to form communication between the hosts. The fourth step (S4) is a network connection process, by activating the PPP interface and Ethernet interface to connect the PPP interface to the global network, and connects the Ethernet interface to the private network. The fifth step (S5) is a process of processing NAT, NAT processing by executing a NAT input packet processing process, NAT output packet processing process, NAT timer processing process and NAT command processing process.

According to the conventional NAT processing method described above, the packet received from the router is raised to the TCP / IP layer, and the header is analyzed and sent to the private network. As such, headers are analyzed up to the relatively upper TCP / IP layer, and headers are analyzed and exported to the private network, which is disadvantageous for use in a small network using a single global IP. In particular, in a network with a single IP address connected to an external network, it is inefficient to analyze a header by sending a packet up to the TCP / IP layer and to export it to a private network, so that multiple PCs can be connected to the outside. There is a need to deal with it.

The present invention provides a NAT processing method using a MAC address. In particular, the present invention provides a NAT processing method for making a plurality of PCs suitable for external access in a network having a single IP address connected to the external network.

The present invention provides a process of creating a NAT table for IP / MAC mapping using a private IP address and a MAC address of a terminal in a private network, and converts a packet from a private IP into a corresponding global IP with reference to the NAT table and sends it. And converting the packet coming into the private network from the outside into the corresponding private IP with reference to the NAT table.

Also, in the NAT processing method of the present invention, in order to convert the private IP into a global IP and transmit the same, confirming whether a MAC and an IP address exist by referring to the created NAT table, and converting the source address of the IP header into a global IP. Converting to an address, and transmitting a packet to a destination according to the converted global IP address.

Further, in the NAT processing method of the present invention, in order to convert a packet coming into the private network from the outside into a private IP, retrieving a destination MAC address of the received packet by referring to the NAT table, and the corresponding IP retrieved from the NAT table. Converting the destination address of the header into a private IP address, and transmitting a packet to a destination according to the converted private IP address.

1 is a flowchart showing a conventional network address translation process

2 illustrates an API structure for explaining the present invention.

Figure 3 (a) is a diagram showing a NAT table for explaining the present invention

(b) shows an IP / MAC table for explaining the present invention;

4 is a diagram illustrating a network configuration for explaining the present invention.

5 is a flowchart showing a network address translation processing method of the present invention;

Figure 2 shows the structure of an API (Application Program Interface) for explaining the present invention. The API is based on a computer operating system (OS), and the physical layer protocol (PHY) for encoding and processing data from the network address translation (NAT) for the network address translation and the media access control (MAC) of the data link layer. Is mounted.

3 shows an example of a NAT table for explaining the present invention. The NAT table as shown in FIG. 3 (a) requests a request to obtain private IP addresses and MAC addresses of PCs in a private network at a router, and receives and writes a response thereto. Figure 3 (b) shows a packet, source IP (source IP), destination IP (Destination IP), source MAC (Source MAC), destination MAC (Destination MAC).

4 shows an example of a network configuration for explaining the present invention. The private network 1, the router 2, and the global network 3 are represented, and a packet is transmitted from the PC 1a of the private network 1 to the destination 3a of the global network 3 (f1-> f2). When the packet is transmitted from the source 3a of the global network 3 to the destination 1a of the private network (f3-> f4), the router 2 performs NAT processing. In FIG. 4, the private IP, the corresponding MAC, the global IP, and the corresponding MAC are simultaneously described.

5 is a flowchart showing a NAT processing procedure of the present invention. As described above, the router requests a request to obtain the private IP address and the MAC address of the PCs in the private network, receives the response, and creates a NAT table as shown in FIG. .

In addition, in executing the procedures S11, S12, and S13 for processing packets from the private network to the external network, the NAT table is referred to, and the procedures for processing packets from the external network to the private network (S21, S22, S23). In executing, refer to the created NAT table.

First, a process of processing a packet going from a private network to an external network will be described. This process converts the packet from the private IP into the global IP and sends it. In the first step S11, it is checked whether the MAC and the IP address exist in the NAT table. In the second step S12, the source address of the IP header is converted into a global IP address (see FIG. 3), and in the third step S13, the corresponding packet is transmitted to the converted global IP address (destination), thereby providing a private network. When exporting to global network, private IP address of packet received from PC is converted to global IP address and transmitted.

Next, a process of processing a packet coming into the private network from the external network will be described. This process converts the packet from the global network to the private IP and sends it to the private IP. In the first step S21, the destination MAC address of the incoming packet is referred to the table (see FIG. 3) and corresponds to the MAC address. Find your private IP address. In the second step S22, the destination address of the IP header is converted into the corresponding private IP address searched by referring to the NAT table, and in the third step S33, the converted private IP address, that is, the destination of the internal network, is converted. By transmitting the packet, an operation for converting the packet from the outside to the private IP address and sending the private IP address is performed.

The present invention performs NAT processing using a MAC address. According to the present invention, a NAT table may be created, and a packet may be transmitted to a destination by converting a private IP into a global IP with reference to the NAT table for a packet going out from the private network, and transmitting the packet to a destination from the external network. By referring to the table, the global IP can be converted into a private IP and the packet can be transmitted to the destination of the internal network.

Therefore, the present invention is advantageous in a small network using a single global IP, rather than a packet up to the conventional TCP / IP layer to analyze the header and send it out to the private network. In particular, at home, multiple PCs can be configured as private networks, allowing access to external networks using a single global IP. In addition, it is very useful because it is possible to include the API of the present invention in an image for initialization in a SOHO or a router that can enter a home, so that the NAT function can be performed.

Claims (4)

Creating a NAT table for IP / MAC mapping by using private IP addresses and MAC addresses of terminals in a private network; converting packets from private IPs to corresponding global IPs by referring to the NAT table; And converting a packet coming into the private network from the outside into the corresponding private IP by referring to the NAT table. The method of claim 1, further comprising: checking whether a MAC and an IP address exist by referring to the created NAT table to convert the private IP into a global IP and to transmit the private IP, and converting a source address of the IP header into a global IP address. And transmitting a packet to a destination according to the translated global IP address. The method of claim 1, further comprising: retrieving a destination MAC address of the received packet by referring to the NAT table to convert a packet coming into the private network from the outside into a private IP, and a destination of the corresponding IP header retrieved from the NAT table. Translating the address into a private IP address, and transmitting a packet to a destination according to the converted private IP address. 2. The method of claim 1, wherein the NAT table includes a source IP, a destination IP, a source MAC, and a destination MAC corresponding to the packet.