JP2001060973A - Network address converter, network provided with this and its storing medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a virtual network address by each network in a network address converter, a network provided with this and its storing medium. SOLUTION: A network address converter 2 mutually converts a virtual network address and a real network address. The virtual network address in a network 3 consists of the network address of the virtual network address defining the network 3 and a host address defining a host 4 belonging to the network 3. The real network address consists of the network address of the real network address and the host address.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network address translator, a network including the same, and a storage medium thereof, and more particularly, to a network address translator capable of setting a virtual network address for each network and a network including the same. And its storage medium.

[0002]

2. Description of the Related Art As shown in FIG. 7A, in the Internet 101, IP addresses are used as network addresses.
The address is used. The IP address for connecting to the Internet 101 is a global address (virtual network address). On the other hand, a network address used in a private network such as the intranet 103 is called a private address (real network address).

[0003] The private address cannot directly access the Internet 101. However, because of this, there is an advantage that it does not collide with the IP address.
Network addresses can be freely assigned within the network 03, which is convenient. In addition, through a proxy server or a firewall or a router having an address translation function, each host (host computer or node) 104 of the intranet 103 can actually access the Internet 101 without any inconvenience. In addition, from the viewpoint of security, it is more convenient to restrict access to the Internet 101 and access from the Internet 101 by providing a firewall. From the viewpoint of communication economy, it is more convenient to reduce traffic by providing a proxy server.

[0004] From the above, most intranets 1
In 03, a private address is adopted and only the host 104 can indirectly access the Internet 101. Therefore, the host 104 in the intranet 103 does not have a global address but only has a private address. For this reason, a host 104 in the intranet 103 having only a private address is
When accessing to the Internet, and when accessing from the Internet 101 to the host 104 in the intranet 103, network address translation is required. That is,
It is necessary for the network address translator (NAT) 102 to mutually translate an IP address and a private address.

[0005] By this network address conversion, a host 104 having only a private address can transparently access the Internet 101. From the Internet 101 side, it looks like an access by the converted global address.

[0006]

As shown in FIG. 7A, in order to perform network address conversion in the intranet 103, global addresses Av to Mv are sent to all the hosts 104A to 104M connected to the intranet 103. Need to be set. The global address is a virtual (logical) address on the Internet 101 (a virtual network address). The setting of the global address for the host 104 is performed as follows. That is, one global address is assigned to one host 104. In other words, the global address is assigned to the host 1
This is done in units of 04. On the other hand, a private address (real network address) which is a physical (real) address on the intranet 103 for the host 104
Is defined for each machine. Therefore, the operation is performed such that the global address and the private address correspond one-to-one.

In order to perform network address translation, a translation table 106 for network address translation must be prepared in the network address translation device 102 as shown in FIG. That is, 1
A translation table 106 is provided for storing a global address and a private address corresponding to one-to-one in association with each other, and uses this to translate a network address.

For this reason, when the intranet 103 becomes large and the number of hosts 104 increases, the following problems arise.

That is, as the number of hosts 104 increases, the burden of assigning a global address to each host 104 at the start of operation of the intranet 103 increases.
For example, in the case of an IPv4 address, an IP address having a length of 32 bits is assigned to each host 104, and an IPv6 address is assigned.
In the case of an address, an IP address having a length of 128 bits must be assigned to each host 104. Also,
After the operation starts, a new host 1 is added to the intranet 103.
When adding 04, it is necessary to re-assign the global address depending on the relationship with other global addresses, so the operation is troublesome.

When the number of hosts 104 increases, the size of the conversion table 106 increases, which consumes a lot of memory resources. Further, every time a new host 104 is added, the conversion table 106 must be rewritten.

An object of the present invention is to provide a network address translator that can set a virtual network address for each network.

Another object of the present invention is to provide a network in which a virtual network address can be set for each network.

Another object of the present invention is to provide a storage medium for storing a program for realizing a network address translator capable of setting a virtual network address for each network.

[0014]

FIG. 1 is a block diagram showing the principle of the present invention, and shows a network address translator 2 according to the present invention. The network address translator 2 translates a real network address used in the network 3 and a virtual network address used in the network 1 from each other. The virtual network address includes a network address of the virtual network address defined for the network 3 and a host address defined for the host 4 belonging to the network 3. The real network address includes a network address and a host address of the real network address.

The network address translator 2 of the present invention
According to the above, the network address of the virtual network address defined for the network 3 and the network address of the real network address are defined in advance so as to correspond one-to-one, and these are mutually converted and the host address of the host address is converted. The part is used in common for both.
This eliminates the need to individually assign a virtual network address to all the hosts 4 belonging to the network 3. That is, only the host address, for example, only 8 bits may be assigned. Therefore, the work of allocating the entire virtual network address to each host 4 can be eliminated. When a new host 4 is added, it is not necessary to reassign a virtual network address, and it is only necessary to define a host address for the host 4 independently of the other hosts 4. Further, even if the number of hosts 4 increases, the conversion table 6 (see FIG. 3B) does not become large.
Even when a new host 4 is added, there is no need to rewrite the conversion table 6.

[0016]

FIG. 1 will be further described. FIG.
Shows a network configuration and includes a network address translator (NAT) 2 of the present invention.

The network 3 is, for example, an intranet 3, and is connected to a global network 1, for example, the Internet 1 via a public line or a dedicated line (not shown). Intranet 3 has 1
Network address translator 2 and a plurality of hosts (host computers or nodes) 4A to 4M belonging to the intranet 3.

The network address translator 2 is provided at the highest level of the intranet 3, that is, at a connection point with the Internet 1, which is an external network. Therefore,
The host 4 of the intranet 3 is connected to the Internet 1 only via the network address translator 2,
The user cannot access the Internet 1 directly. The network address translator 2 includes, for example, a router of the network 3 or a firewall of the network 3. The proxy server of the network 3 may be used.

FIG. 2 shows a network address translator 2
As shown in (1), a private address (private IP address) A that is a real network address and a global address (global IP address) Av that is a virtual network address are mutually converted. The real network address is defined for each host (machine) 4 in the network 3 and indicates a physical (real) position of the host 4 on the network 3. The virtual network address is an address other than the real network address, and indicates a logical (virtual) position of the host 4 on the network 1 separately from the real network address. Private address A is
Network address of private address 192.168.
171 and a host address 111. The global address Av includes a global address network address 202.71.2 and a host address 111. Therefore,
The IP address in this example is class C. In addition,
These network addresses are examples.

The network address of the global address is defined for each network 3 according to the present invention. That is, the intranet 3 is defined (assigned) in advance. The network address of the private address and the network address of the global address have a one-to-one correspondence, and are mutually converted by the conversion table 6. The host address is a host 4 belonging to the network in the intranet 3.
Each is uniquely defined (assigned) and common to both network addresses. Conventionally, a private address and a global address are defined for each host 4, are associated one-to-one, and are mutually converted by the conversion table 106.

For this purpose, the network address translator 2 comprises an address translator 5 for performing an address translation process described later, and a translation table 6 therefor, as shown in FIG. As shown in FIG. 3B, the conversion table 6 stores a network address Nv of a global address defined for the network and a network address N of a corresponding private address. The address conversion unit 5 uses the conversion table 6 to convert a global address and a private address into each other.

Therefore, the intranet 3 is a network as described below. That is, the network 3
The global address of the network 3
And the host address defined for the host 4 belonging to the network. Further, the private address is composed of a network address and a host address of the private address. Moreover,
It has a network address translator 2 for translating between a private address and a global address.

When transmitting an IP packet from a certain host 4 in the intranet 3 to the Internet 1, the network address translator 2 translates a private address into a global address. In addition, when an IP packet to a certain host 4 in the intranet 3 is transmitted from the Internet 1, the network address translator 2 translates a global address into a private address.

Specifically, when translating a private address into a global address, the network address translator 2 sequentially performs a check process and a global address creation process.

The check process is a process for checking whether or not the IP address included in the IP packet to be transmitted is included in the network address of the private address. In the check processing, first and second values for the check are obtained, and these are compared. The first value is a value obtained by a logical product (AND) of an IP address including a private address included in the IP packet and a net mask of the private address. The second value is a value obtained by a logical product of a network address of the private address and a net mask of the private address.

If the two match in the checking process, a global address creating process is performed. That is, the logical sum (O) of the network address of the global address and the host address extracted from the private address
R) to determine a global address.

In this case, a host address extraction process is performed as a pre-process of the global address creation process. The extraction of the host address from the private address is performed by calculating the logical product of the IP address composed of the private address included in the IP packet and the inverted netmask of the private address.

The network address translator 2
Performs a check process and a private address creation process in order to convert a global address into a private address.

The check process is a process for checking whether or not the IP address included in the transmitted IP packet is included in the network address of the global address. In the check processing, third and fourth values for the check are obtained, and these are compared. The third value is a value obtained by a logical product of an IP address composed of a global address included in the IP packet and a net mask of the global address. The fourth value is
This is a value obtained by the logical product of the network address of the global address and the net mask of the global address.

If the two match in the checking process, a private address creation process is performed. That is, the private address is obtained by the logical sum of the network address of the private address and the host address extracted from the global address.

In this case, a host address extraction process is performed as a pre-process of the private address creation process. The extraction of the host address from the global address is performed by calculating the logical product of the IP address including the global address included in the IP packet and the inverted netmask of the global address.

Hereinafter, the processing of the address conversion unit will be described with reference to the address conversion processing flow executed by the address conversion unit 5 shown in FIGS.

As an example, as shown in FIG. 5A, a network address N of a private address of an intranet 3 is (192.168.171.0), and a net mask M of the private network is (25.
5.255.255.0), the network address Nv of the global address is (202.71.2.0), and the netmask Mv for the global network is (255.255.25
5.0). It is also assumed that the host addresses of the receiving (transmission destination) host 4 and the transmitting (transmission source) host 4 of the IP packet are (111).

Therefore, when an IP packet is transmitted from the host 4 to the Internet 1, the private address indicating the transmission source included in the IP packet, that is, the IP packet address A (192.168.171.111) is changed to the global address Av. (202.71.2.111). When an IP packet is transmitted from the Internet 1 to the host 4, the global address Av (2) indicating the destination included in the IP packet is transmitted.
02.71.2.111) to the private address A (192.168.171.1)
It is necessary to convert to 11).

FIG. 4 shows the flow of processing for converting a private address to a global address. That is, an IP packet is transmitted from a certain host 4 in the intranet 3 to the Internet 1. This IP packet contains the IP address (192.168.171.111) of the host 4 as a private address indicating the source host 4.
The first three numbers 192.168.171 of the IP address are the network address, and the last one number 111 is the host address.

The network address Nv of the global address of the intranet 3 to which the host 4 performing the address conversion belongs is referred from the address conversion table 6 (step S1). As described above, the network address of the global address is (202.71.2.0).

The network address # 1 is created by calculating the logical product of the source IP address A of the IP packet and the netmask M of the intranet 3 (step S2). That is, as shown in FIG. 5B, the IP address (192.168.171.111) and the netmask (255.255.25)
5.0) and network address # 1 (192.168.171.
0) is obtained.

The network address # 2 is created by calculating the logical product of the network address N of the private address of the intranet 3 and the net mask M of the intranet 3 (step S3). That is, FIG.
As shown in (C), the network address (192.168.171.0) of the private address and the netmask (255.2
55.255.0), the network address # 2 (192.16
8.171.0) is obtained.

The network addresses # 1 and # 2 are compared to determine whether they match (step S).
4). If they do not match, the process ends.

If they match, the host address of the IP address A is extracted by calculating the logical product of the IP address A and the inverted netmask M of the private network (step S5). In this case, since they match, the IP address is changed as shown in FIG.
(192.168.171.111) and the netmask M (255.255.255.
0), the host address (0.0.0.255)
0.111).

The global address Av is created by calculating the logical sum of the extracted host address and the global address network address Nv (step S6). That is, as shown in FIG. 5E, the global address (202.71.2.111) of the host 4 is obtained from the network address (202.71.2.0) of the global address of the intranet 3 and the host address (0.0.0.111).
Get.

FIG. 6 shows a flow of a conversion process from a global address to a private address. That is, an IP packet to a certain host 4 in the intranet 3 is transmitted from the Internet 1. This IP packet contains the global address of the destination host 4, that is, the IP address Av (202.71.2.111), as the network address indicating the destination host 4. A diagram corresponding to FIG. 5 is omitted.

The address translation table 6 refers to the network address Nv of the global address of the intranet 3 to which the host 4 performing the address translation belongs (step S7). As described above, the network address of the global address is (202.71.2.0).

The network address # 3 is created by calculating the logical product of the destination IP address Av of the IP packet and the netmask Mv of the Internet 1 (step S8). That is, the IP address (202.71.2.111)
And the netmask (255.255.255.0) to obtain the network address # 3 (202.71.2.0).

The network address # 4 is created by calculating the logical product of the network address Nv of the global address of the intranet 3 and the net mask Mv of the Internet 1 (step S9). That is, the network address of the global address (202.71.2.0)
And the netmask (255.255.255.0) to obtain the network address # 4 (202.71.2.0).

The network addresses # 3 and # 4 are compared to determine whether they match (step S1).
0). If they do not match, the process ends.

If they match, the host address of the IP address Av is extracted by calculating the logical product of the IP address Av and the inverted global network netmask Mv (step S11). in this case,
Since both match, the global IP address (202.71.
2.111) and the inverse of the netmask (255.255.255.0) (0.
From 0.0.255), the host address (0.0.0.111) is obtained.

The private address A is created by calculating the logical sum of the extracted host address and the network address N of the private address (step S12). That is, the network address (192.168.171.0) of the private address of the intranet 3
From the host address (0.0.0.111), the host 4
Get private address (192.168.171.111).

Although the present invention has been described with reference to the embodiments, the present invention can be variously modified within the scope of the gist.

For example, the case where the global address is an IPv4 address (32 bits) has been described, but the present invention can be similarly applied even when the global address is an IPv6 address (128 bits).

The network 1 using the global address is not limited to the Internet 1 but can be similarly applied to various networks outside the network 3. Further, the network 3 is not limited to the intranet 3 but can be applied to various networks. That is, the present invention can be widely applied when different network addresses are used inside and outside one noted network 3.

[0052]

As described above, according to the present invention,
In the network address translator, the network address of the virtual network address defined for the network and the network address of the real network address are previously defined so as to correspond one-to-one, and these are converted to each other and the host address is converted. Is used in common by both sides, it is possible to eliminate the need to individually assign a virtual network address to all hosts belonging to the network, so that the work of the assignment can be eliminated and the conversion table can be reduced. Thus, when a new host is added, reassignment of the virtual network address and rewriting of the translation table can be made unnecessary.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an explanatory diagram of network address conversion.

FIG. 3 is an explanatory diagram of a network address translation device.

FIG. 4 is a flowchart of a network address conversion process.

FIG. 5 is an explanatory diagram of network address conversion.

FIG. 6 is a flowchart of a network address conversion process.

FIG. 7 is an explanatory diagram of a conventional technology.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internet 2 Network address translator 3 Intranet 4 Host 5 Address translator 6 Translation table

Claims (10)

[Claims] 1. A virtual network address in a network, comprising a network address of a virtual network address defined for the network and a host address defined for a host belonging to the network, a network address of the real network address, and the host address. And a real network address comprising: 2. A translation table for storing a network address of a virtual network address defined for the network and a network address of a real network address, wherein the translation table is used to determine the virtual network address and the real network address. The network address translation device according to claim 1, wherein the translation is performed mutually. 3. When the real network address is converted into the virtual network address, a first logical product of an IP address composed of the real network address included in an IP packet and a netmask of the real network address is obtained. Is compared with a second value obtained by the logical product of the network address of the real network address and the netmask for the real network address, and when they match,
2. The network address translation device according to claim 1, wherein the virtual network address is obtained by a logical sum of a network address of the virtual network address and the host address extracted from the real network address. 4. The method for extracting the host address from the real network address is a logical product of an IP address composed of the real network address included in the IP packet and an inverted net mask of the real network address. 4. The network address translator according to claim 3, wherein 5. When converting the virtual network address into the real network address, a third logical product of the virtual network address included in the IP packet and a net mask of the virtual network address is calculated. Is compared with a fourth value obtained by a logical product of a network address of the virtual network address and a net mask of the virtual network address, and when they match, the network address of the real network address is compared. 2. The network address translation device according to claim 1, wherein the real network address is obtained by a logical sum of the host address extracted from the virtual network address. 6. The extraction of the host address from the virtual network address is performed by logically ANDing an IP address including the virtual network address included in the IP packet and an inverted netmask of the virtual network address. 6. The network address translation device according to claim 5, wherein 7. The network address translator according to claim 1, wherein the network address translator comprises a router of the network. 8. The network address translator according to claim 1, wherein the network address translator comprises a firewall of the network. 9. A virtual network address in the network, comprising a network address of a virtual network address defined for the network, and a host address defined for a host belonging to the network, wherein a real network address and the virtual network address are defined. A network having a network address translation function for translating data into each other. 10. A computer-readable storage medium storing a program for translating between a virtual network address and a real network address, wherein the program belongs to a network address of a virtual network address defined for the network and belongs to the network. A computer having a program code for mutually converting a virtual network address in the network including a host address defined for a host and a real network address including the network address of the real network address and the host address. A readable storage medium.