JP2003273891A - Address allocation device and router - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an NAT router which can conduct suitable communication, even when an application for writing IP address information in a data part of an IP packet is conducted. <P>SOLUTION: The NAT router 100 assigns the same address as a public IP address (B) allocated to a global interface of the router to one computer 400a, connected to an internal network. The router 100 assigns the same address as a public IP address (A) of a host UP unit 200 and a designated private IP address (X) in a local interface. Thus, even if the IP packet, in which the public IP address in written in the data part, is sent from an external network to the internal network, proper communication can be conducted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an address assigning device and a router, and more particularly to an address assigning device and a router having an assigning function for assigning an IP address to a device connected to an internal network.

[0002]

2. Description of the Related Art Conventionally, NAT (network address tr
anslation) or NAPT (network address port tra
There is known a router device having an nslation) function. Such a router device has a global interface for connecting to an external network and a local interface for connecting to an internal network. The Internet is a specific example of the external network, and the specific example of the internal network is
A LAN (local area network) and the like can be mentioned.

The router replaces the public IP address used in the external network included in the header portion of the received IP packet with the private IP address used in the internal network, or changes the private IP address into the public IP address. It is a device that performs communication between interfaces by replacing the interface.

[0004]

However, there is a problem that some applications cannot communicate via the router device.

FIG. 12 is a diagram showing the structure of an IP packet transmitted and received via the router device. Referring to the figure,
The IP packet is composed of a header part and a data part, and the router device has a public I written in the header part.
Communication between the external network and the internal network is performed by changing the P address or the private IP address.

However, some applications write the information of the IP address of the device for communication not only in the header portion of the IP packet but also in the data portion. Even in such IP packet communication, since the router device only rewrites the IP address information in the header portion, there is a contradiction between the IP address information in the header portion and the IP address information in the data portion, resulting in communication failure. It is possible.

That is, since the application writes the IP address information in an arbitrary format in the data part in an arbitrary format, the router device cannot rewrite the IP address information in the data part.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an address assigning device and a router capable of solving communication problems.

[0009]

To achieve the above object, according to one aspect of the present invention, an address assigning device has an assigning function for assigning an IP address to a device connected to an internal network, An address allocation device, characterized by allocating a public IP address used in an external network to a device connected to an internal network.

According to the present invention, the public IP address used in the external network can be assigned to the device connected to the internal network, so that the trouble of communication using the device can be solved. It will be possible.

According to another aspect of the present invention, a router uses a global interface for connecting to an external network, a local interface for connecting to an internal network, a public IP address used in the external network, and an internal network. And a first allocating means for allocating the public IP address to the first device connected to the internal network.

According to the present invention, since the public IP address can be assigned to the first device connected to the internal network, it is possible to solve the problem of communication using the device.

Preferably, the first allocating means assigns the same address as the public IP address assigned to the router,
Allocate to the first device.

In this way, by allocating the same address as the public IP address allocated to the router to the first device, it is possible to eliminate inconsistencies in communication and solve communication problems. Become.

Preferably, the router further comprises second allocating means for allocating the private IP address to the second device connected to the internal network.

According to the present invention, since the private IP address can be assigned to the second device different from the first device, communication between the devices connected to the internal network becomes possible.

Preferably, the router further includes a transmission / reception filter for filtering IP packets to be relayed.

According to the present invention, since the data can be filtered by the transmission / reception filter, the usability of the device is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a router 100 having a NAT (or NAPT) function and a network connected thereto.

Referring to the figure, router 100 is connected between an external network and an internal network, and has a function of mutually converting a public IP address used in the external network and a private IP address used in the internal network. Have.

Further, the router 100 has a function of allocating a public IP address to a device such as a computer connected to the internal network.

In FIG. 1, a plurality of computers 400a to 400c are connected to the internal network. The router 100 is connected to the internal network by its local interface.

In the external network, the router 100
Is the top IP due to its global interface
It is connected to the device 200 (such as a router of a line provider). The upper IP device 200 is connected to the Internet 300. Thus, the computers 400a to 400c can be connected to the Internet 300 via the router 100.

Also, the router assigns the same address as the public IP address (A) of the upper IP device 200 to its local interface, and assigns the same address as the public IP address (B) of its global interface to one of the internal networks. Computer (here, computer 400a).

The computers (here, computers 400b and 400c) to which the same address as the public IP address (B) has not been assigned are assigned private IP addresses (Y) and (Z) as in the conventional case.

Furthermore, the local interface of the router 100 is assigned a private IP address (X) together with the public IP address (A), and the local interface of the router is logically duplicated on the IP.

If the method of expressing the address by 8 bits × 4 is adopted here, as a concrete example of the private IP address: x. x. x 172.16. x. x to 172.31. x.x 192.168. x. x (x is a numerical value of 1 to 255) is generally used. Any other IP address is used as the public IP address.

To access the computer, the IP address, the protocol number (1 to 65535) and the port number (1 to 65535) are required. This I
A set of P address, protocol number, and port number is called "address information".

FIG. 2 is a block diagram showing the hardware configuration of the router 100. Referring to the figure, the router 100
Is a CPU 103 that controls the entire apparatus, a global interface 101 that functions as an interface between an external network and a router, a local interface 105 that functions as an interface between an internal network and a router, and a bus 107 that transmits signals.
And a volatile memory 109 for temporarily storing information such as a source IP address and a destination IP address.
And a non-volatile memory 111 for recording a router control program and the like shown in a flowchart described later.

FIG. 3 is a flow chart showing a relay process performed by the router between the external network and the internal network.

Referring to the figure, in step S101a, the internal network I
Reception of P packet is performed, or step S1
When an IP packet is received from the external network via the global interface in 01b, the IP packet is filtered (reception side) in step S103. As a result, passage of unnecessary IP packets is prohibited.

In step S105, the volatile memory 109
A process (IP relay process) of rewriting the IP address and the like in the header part of the IP packet is performed based on the information recorded in (source address IP address information list).

Thereafter, when transmitting the IP packet to the external network or the internal network, the transmitting side filtering process is performed in step S107, and the IP packet is transmitted via the local interface or the global interface in step S109a or step S109b. To be done.

After the IP relay processing, if the IP packet is for the router, it is processed as an IP packet addressed to itself in step S111.

Next, the function of the router in this embodiment will be described. The router has a function of logically duplicating the local interface of the router and a function of allocating the IP address (public IP address (A)) given to the upper IP device to the local interface of the router. Further, the router has an address allocation function of automatically allocating the IP address (public IP address (B)) allocated to the global interface to the computer (IP host) connected to the local interface.

The volatile memory constitutes a storage unit for storing a "list of combinations of source IP address information and destination address information of IP packets during communication". The router has a function of comparing a combination list stored in the storage unit with an IP packet used for communication, and a switch function of distributing communication between a logically duplicated local interface and global interface.

Thus, in a network environment where only a single public IP address can be used, N
While maintaining the function of AT (or NAPT) router,
The computer assigned a public IP address is I
It becomes possible to use an application that writes address information in the data portion of the P packet.

Next, the outline of the processing performed by the router 100 will be described. First, as a preliminary process, the router logically duplicates the local interface of the router in advance. After that, the IP address allocation processing as shown in the following (1) to (5) is performed.

(1) Public I that the upper IP device 200 automatically allocates to the global interface of the router
The P address and the public IP address of the upper IP device 200 are given to the router.

(2) The router sets the public IP address of the upper IP device in one of the logically duplicated local interfaces, and sets the private IP address designated by the user in the other.

(3) The router assigns the public IP assigned to the global interface of the router to the computer initially connected to the local interface side or the computer having the ID (MAC address etc.) specified by the user. Assign an address.

(4) A private IP address is given to a computer other than the computer to which the public IP address is assigned and which is connected to the local interface side.

(5) Every time the public IP address automatically allocated to the global interface of the router from the upper IP device 200 and the public IP address of the upper IP device are changed, the processes of (1) to (3) above are performed. And repeat.

Further, the router executes the following processes (1) to (4) as the IP relay process.

(1) The IP packet received by the router is compared with the stored list of sets of source IP address information and destination IP address information.

(2) Source I of the received IP packet
P address information and stored destination IP address information,
When the destination IP address information of the received IP packet and the stored source IP address information match, the router performs NAT conversion and relays to the local interface or the global interface.

(3) IP address information of IP packet, stored source IP address information and destination IP
If the list of address information sets does not match and the IP packet is received at the global interface,
If permission is set, the IP packet is relayed to the local interface without address translation, and if permission is not set, it is discarded. Then, a set of the source IP address information and the destination IP address information is stored.

(4) IP address information of IP packet, stored source IP address information and destination IP
When the list of address information sets does not match and the IP packet is received at the local interface, the following processing is performed.

(A) Destination I of the received IP packet
If the P address is an address belonging to the network of the private IP address assigned to the local interface of the router or a public IP address assigned to the global interface of the router, relay to the logically duplicated local interface. To do.

(B) Destination I of the received IP packet
P address is a private IP address assigned to the local interface of the router, or public I assigned to the local interface of the router.
If it is the same as the P address, it is processed as communication addressed to the router itself.

(C) Destination I of the received IP packet
If the P address does not match any of the above,
Converts the source address information of the IP packet and relays it to the global interface.
A set of address information and destination IP address information is stored.

Further, the router has the following security check function. That is, the transmission / reception IP filter processing is performed in any case in the relay from the global interface to the local interface and in the relay from the local interface to the global interface to prevent an illegal IP packet from passing.

As described above, in the present embodiment, the I or
By allocating a public IP address to the P device, an application that writes IP address information in the data portion of the IP packet can be used. Moreover, the function of the conventional NAT / NAPT router can be continuously realized, and in addition, the security function that does not send the IP packet to the computer to which the public IP address is allocated and which has the designated IP header is realized. is doing.

4 and 5 are flowcharts showing the IP address allocation processing performed by the router.

FIG. 4 is a flow chart showing the processing when the user has designated (ID setting) a computer for allocating a public IP address, and FIG. 5 is a flow chart.
It is a flow chart which shows processing when ID is not set up by a user.

Referring to FIG. 4, in step S101, it is determined whether an address request comes from the IP device (computer or the like) to the local interface, and YES.
Wait until. If YES, step S10
At 3, it is determined whether the requesting IP device has a specific ID. If YES, in step S105,
It is determined from the upper IP device 200 whether an IP address is assigned to the router. If YES, in step S107, the public IP address (public IP address (B)) assigned to the router is assigned to the IP device that transmitted the request.

If NO in step S103, a private IP address is sent to the IP device in step S111.
Assign an address.

If NO at step S105,
In step S109, a temporary IP address is assigned to the IP device.

Referring to FIG. 5, when the user has not set the ID, it is determined in step S201 whether an address request from the IP device has arrived at the local interface of the router, and the process waits until YES. To do.

If YES in step S201, in step S203 the global IP address or temporary I
It is determined whether the P address is not assigned to another IP device. If YES, it is determined in step S205 whether the IP address is assigned to the router from the upper IP device 200. If YES, the public IP address assigned to the global interface of the router is assigned to the IP device in step S207. .

If NO in step S203, a private IP address is sent to the IP device in step S211.
Assign an address.

If NO in step S205,
In step S209, a temporary IP address is assigned to the IP device.

FIG. 6 is a flowchart showing the IP address allocation processing to the local interface of the router.

Referring to the figure, in step S501, the set private IP address is assigned to the local interface of the router. In step S503, it is determined whether the upper IP device 200 has an IP address assigned to the global interface of the router.
If YES, the IP address of the upper IP device is assigned to the local interface of the router in step S505. In step S507, it is determined whether the IP address is newly added or changed in the global interface of the router. If YES, the process returns to step S505.

If NO in step S503,
In step S509, a temporary IP address is assigned to the local interface of the router.

7 to 9 are flowcharts showing the IP relay processing when the router receives the IP packet from the local interface. The flowcharts of FIGS. 7 to 9 show a series of processes.

Referring to FIG. 7, in step S301, if the IP packet is received from the local interface, the reception filter checks the IP packet. In step S303, it is determined whether or not reception of the packet is permitted, and if NO, step S317.
Then, the IP packet is discarded.

On the other hand, if reception is permitted,
In step S305, the information of the source and destination IP addresses of the received IP packet is compared with the list of the sets of source and destination IP address information stored in the database (storage unit).

In step S307, it is determined whether or not the same information exists in the database. If YES, in step S309, the source IP address information of the IP packet is set to the global interface IP address of the router.
Rewrite with address information. Next, in step S311, the transmission filter checks the IP packet. Step S
At 313, it is determined whether the transmission is permitted. If NO, the IP packet is discarded at step S329, and if the transmission is permitted, the IP packet is transmitted from the global interface at step S315.

If NO at step S307,
Whether the destination IP address information of the IP packet in step S351 is an address belonging to the same network as the private IP address assigned to the local interface of the router or a public IP address assigned to the global interface of the router Is determined. If YES, step S3
At 53, the transmission filter checks the IP packet. In step S355, it is determined whether the transmission is permitted,
If NO, the IP packet is discarded in step S359, and if the transmission is permitted, the IP packet is transmitted from the local interface in step S357.

If NO in step S351, it is determined in step S361 whether or not the destination IP address information of the IP packet is the IP address assigned to the local interface of the router. If YES, it is determined in step S363. IP packets are processed as communications to the router itself.

If NO at step S361, at step S365, the I and I of the transmission destination and the transmission source are stored in the database.
The set of P address information is stored, and the process proceeds to step S309.

FIGS. 10 and 11 show the I of the router when an IP packet is received from the global interface.
It is a flow chart which shows P relay processing. The flowcharts shown in FIGS. 10 and 11 show a series of processes.

Referring to the drawing, when an IP packet is received from the global interface, step S4
At 01, the reception filter checks the IP packet.

In step S403, it is determined whether the reception is permitted. If NO, then in step S417 the I
Discard the P packet.

If the reception is permitted, in step S405, the combination of the source and destination IP address information of the received IP packet and the source and destination IP address information stored in the database. Compare with the list of.

In step S407, it is determined whether the same information exists in the database. If YES, in step S409, the destination IP address information of the header part in the IP packet is rewritten based on the stored IP address information. It

In step S411, the transmission filter checks the IP packet, and in step S413, it is determined whether transmission is permitted. If not permitted, the IP packet is discarded in step S423, and if permitted, the IP packet is transmitted from the local interface in step S415.

If the same information does not exist in the database in step S407, it is determined in step S419 whether transmission to the device having the global IP address on the local interface side is permitted.
If YES, the process proceeds to step S411, and if NO, the IP packet is discarded in step S421.

In the above embodiment, the router is taken as a specific example of the device for allocating the address, but the address may be allocated by a device such as a server or other computer related equipment. .

Further, the processing carried out by the apparatus in the above-described embodiments may be carried out using a hardware circuit or software.

It is also possible to provide a program for executing the processing of the flowcharts in the above-described embodiments, and the program can be stored in a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM or a memory card. It is also possible to record it in the above and provide it to the user. Further, the program may be downloaded to the device via a communication line such as the Internet.

Further, in the above-mentioned embodiment, the computer is mentioned as an example of the device connected to the network, but the present invention can be implemented even when other portable terminals, IT home appliances, etc. are connected to the network. Is.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[Brief description of drawings]

FIG. 1 is a NAT in one of the embodiments of the present invention.
It is a figure which shows the structure of the router equipped with (or NAPT) function and the network connected to it.

FIG. 2 is a block diagram showing a hardware configuration of a router 100.

FIG. 3 is a flowchart showing a relay process performed by a router.

[FIG. 4] I when ID is set by a user
It is a flow chart which shows P address allocation processing.

FIG. 5 is a flowchart showing an IP address allocation process when an ID has not been set by the user.

Figure 6 IP to router local interface
It is a flowchart which shows an address allocation process.

FIG. 7 is a flowchart showing an IP relay process when an IP packet is received from a local interface.

FIG. 8 is a flowchart following FIG.

FIG. 9 is a flowchart following FIG.

FIG. 10 is a flowchart showing an IP relay process when an IP packet is received from the global interface.

FIG. 11 is a flowchart following on from FIG.

FIG. 12 is a diagram showing a structure of an IP packet.

[Explanation of symbols]

100 router, 101 global interface, 103 CPU, 105 local interface, 107 bus, 109 volatile memory, 111 non-volatile memory, 200 upper IP device, 300 Internet, 400a-400c computer.

Claims (5)

[Claims] 1. An address allocation device having an allocation function for allocating an IP address to a device connected to an internal network, the device being used in an external network for a device connected to the internal network. An address allocation device characterized by allocating a public IP address. 2. A global interface for connecting to an external network, a local interface for connecting to an internal network, a public IP address used in the external network, and a private IP address used in the internal network. A router comprising: a conversion unit configured to convert each other to each other; and a first allocation unit configured to allocate a public IP address to the first device connected to the internal network. 3. The first allocation means assigns the same address as the public IP address allocated to the router,
The router according to claim 2, wherein the router allocates to the first device. 4. A second device connected to the internal network
The router according to claim 2 or 3, further comprising second allocating means for allocating a private IP address to the device. 5. The router according to claim 2, further comprising a transmission / reception filter that filters an IP packet to be relayed.