WO2004042976A1

WO2004042976A1 - Unauthorized reception preventive device and method

Info

Publication number: WO2004042976A1
Application number: PCT/JP2002/011631
Authority: WO
Inventors: Yoshimi Kikuchi; Emiko Kobayashi; Masahiro Koyano
Original assignee: Fujitsu Limited
Priority date: 2002-11-07
Filing date: 2002-11-07
Publication date: 2004-05-21
Also published as: JP3963916B2; JPWO2004042976A1

Abstract

Unauthorized reception is prevented by a simple method without giving any loads on the transmission/reception of multi-cast data, and without affecting the existing network configuration. The multi-cast data from a server (1) is transmitted to a relay (4) on a sub-network (12) (Step S1). An unauthorized reception preventive device (3) is connected to the inside of the sub-network (12), and receives a reception request signal from a reception terminal (2b) (Step S3-3) to specify the reception terminal. A determination unit (31) determines whether the reception terminal is permitted for reception according to authentication information (3a) to the reception terminal registered in advance. If determined non-permissible (Step S4), a DOS attack processing unit (32) performs the DOS attack of transmitting the predetermined signal so as to increase the processing load to the unauthorized reception terminal (Step S5).

Description

Description Unauthorized reception prevention device method Technical field

The present invention is directed to a method for preventing illegal reception of multicast data that prevents the multicast data transmitted from the server from being illegally received by a receiving terminal connected to the server via a network, and a method for preventing such illegal reception of multicast data. The present invention relates to a data distribution system in which reception is prevented and an unauthorized reception prevention device. Background art

In recent years, attention has been paid to IP multicast for communication between one-to-many or many-to-many nodes on the Internet. In IP multicast communication, a group (called a multicast group) on the network that needs information is defined, and the sender specifies this group by the multicast group ID and sends the information once. By performing only the above, information can be delivered to multiple hosts in the group.

However, due to such a structure, any receiver can receive the information if it can know the multicast group ID. Also, since the multicast group ID indicates a certain range of addresses on the network, it is possible to steal the address system more easily than the multicast address. Therefore, there is a need for a mechanism that prevents recipients who have not undergone valid procedures or who can continue receiving even if the expiration date has expired from receiving IP multicast data.

As such a technique, there is a method of transmitting multicast data after encrypting it. For example, an authentication server that manages the information of the authorized recipient and the decryption key is provided, and the recipient obtains the decryption key from the authentication server and uses the decryption key to transmit the encrypted data from the sender. To decrypt.

There are also the following methods. First, the sender of the multicast data It sends secret information about encryption to the key management server and transmits the information about encryption to the receiver on the transmission line. The information encrypted and sent from the sender is sequentially encrypted by each router on the transmission line using the above information and information unique to each router, and delivered to the receiver. The receiver receives in advance the key request information encrypted by such a method from the sender, and passes the key request information to the key management server, thereby obtaining a decryption key for the information passing through a specific transmission path. Once obtained, multicast data can be decrypted normally using this decryption key. Therefore, even if the encryption key is scattered, the information other than the information transmitted on the same path cannot be decrypted. For example, refer to Japanese Patent Application Laid-Open No. 2002-124904 (paragraph numbers [0 14] to [0 24], FIG. 1).

However, when video data distribution using compression technology such as MPEG (Moving Picture coding Experts Group) is performed by IP multicast communication, especially when transmitting video over a wide band such as 6 Mbps, Large delays occur due to the encryption / decryption processing of moving image data during reception, and this delay hinders smooth streaming reception. Therefore, the method of encrypting the multicast data itself is not appropriate for use in video distribution.

On the other hand, a method is considered in which the validity of the receiver is determined on the route between the sender and the receiver based on the authentication information, and the transmission of information to the receiver is controlled. For example, first, a legitimate recipient first obtains a token indicating that the reception of information has been permitted and a secret key from a certificate authority in advance. The certificate authority notifies the public key that is paired with the private key to the multicast group near the recipient's group. When a legitimate recipient makes a request to receive information to Multicast, it encrypts the above token with a secret key, attaches it to the request, and sends it out. Upon receiving this, the multicast router decrypts the token with the public key. If decrypted, the multicast router continues normal processing for the received request. If unsuccessful, it does not perform processing. This allows the information to be successfully delivered only to the recipient who has the private key).

As described above, in the case where moving image data and the like are distributed using IP multicast communication, from the viewpoint that the load of the encryption / decryption processing is large, the data is transmitted as in the method disclosed in Patent Document 1 above. It is preferable to send the encrypted data Not good.

On the other hand, the validity of the receiver is determined on the route between the sender and the receiver, as in the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2002-124049. To do so, it is necessary to define special communication protocols for network nodes. In this case, for example, it is impossible for a network device such as a router or a switching hub to have a function to process a new protocol for recipient authentication unless it is a vendor of the network device. Also, if this protocol is not standardized, a network must be built with products from one vendor. Therefore, it is difficult to adopt such a method widely. Disclosure of the invention

The present invention has been made in view of such a problem, and prevents unauthorized reception by a simple method without imposing a load on transmission / reception processing of multicast data overnight and without affecting an existing network configuration. It is intended to provide a method for preventing unauthorized reception.

Another object of the present invention is to provide a data distribution system capable of preventing unauthorized reception by a simple method without imposing a load on transmission / reception processing of multicast data and without affecting an existing network configuration. To provide.

Still another object of the present invention is to provide an unauthorized reception preventing device capable of preventing unauthorized reception by a simple method without imposing a load on transmission / reception processing of multicast data and without affecting an existing network configuration. To provide.

In the present invention, in order to solve the above-described problem, as shown in FIG. 1, an unauthorized device that prevents multicast data transmitted from the server 1 over the network from being received by the receiving terminals 2a and 2 illegally. In the reception prevention method, the reception terminals 2a and 2b receiving the multicast data are permitted to receive based on the authentication information 3a for the reception terminals 2a and 2b registered in advance. (Step S 4), and transmits a predetermined signal to the unauthorized receiving terminal 2 b to which reception is not permitted so as to increase the processing load of the receiving terminal 2 b through the network. Do DOS attack Step S5) is provided a method for preventing unauthorized reception.

In such an unauthorized reception prevention method, whether or not the receiving terminals 2a and 2b are permitted to receive multicast data is registered in advance as authentication information 3a. Then, it is determined based on the authentication information 3a whether or not the receiving terminals 2a and 2b receiving the multicast data are permitted to receive. Further, by performing a DOS attack on the unauthorized receiving terminal 2b, the reception of which is not permitted, the processing load of the receiving terminal 2b is increased, and normal reception of multicast data is prevented.

Also, for example, the multicast data from the server 1 is transmitted to the relay device 4 on the sub-network 12 constituting the network 11 and the multicast transmitted from the receiving terminal 2 a or 2 b on the sub-network 12 When the reception request signal for one night is transmitted to all nodes on the sub-network 12, the multicast data is relayed from the relay device 4 that has received the reception request signal to the reception terminal 2 a or 2 b of the reception request source. When a communication system is configured, the reception terminal 2a or 2b receiving the multicast data is specified by receiving a reception request signal through the subnetwork 12. Then, if the receiving terminal 2b of the receiving request is invalid based on the determination based on the authentication information 3a, a DOS attack is performed on the receiving terminal 2b through the sub-network 12 and the receiving terminal 2b Interfering with the normal reception of multicast data at

These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, which illustrate preferred embodiments of the invention. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a principle diagram for explaining the principle of the present invention.

FIG. 2 is a diagram illustrating an example of a system configuration according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of a hardware configuration of the unauthorized reception prevention device used in the embodiment of the present invention. FIG. 4 is a block diagram showing functions of the authentication server.

FIG. 5 is a diagram showing the format of the recipient information stored in the recipient information DB.

FIG. 6 is a block diagram showing functions of the unauthorized reception prevention device.

FIG. 7 is a flowchart showing the flow of registration / update processing of recipient information in the authentication server.

FIG. 8 is a flowchart showing the flow of the unauthorized reception prevention process in the unauthorized reception prevention device.

FIG. 9 is a flowchart showing the flow of the DOS attack process. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the following description of FIG. 1, as an example, it is assumed that the present invention is applied to a multicast data distribution system on an IP (Internet Protocol) network.

As shown in FIG. 1, the present invention mainly comprises a communication system comprising a server 1 for distributing multicast data, and a plurality of receiving terminals 2 a and 2 b for receiving the multicast data via a network 10. In this case, it is realized in the unauthorized reception prevention device 3 connected to the network 10. The unauthorized reception preventing device 3 includes a determining unit 31 that determines whether the receiving terminals 2 a and 2 b receiving the multicast data are permitted to receive the data, and an unauthorized device that is not permitted to receive the data. DOS (Denial of Service) attack on various receiving terminals.

At the time of the judgment by the judging unit 31, the authentication information 3a is referred to. The authentication information 3a indicates whether or not each of the receiving terminals 2a and 2b is permitted to receive the multicast data.Before each of the receiving terminals 2a and 2b receives the multicast data, Registered in advance. The authentication information 3a may be stored in, for example, the unauthorized reception prevention device 3 itself, or may be connected to a network. It may be accumulated in the external device obtained and referred to at the time of the determination by the determination unit 31. If the receiving unit 2b is identified by the determination unit 31 as receiving multicast data illegally, for example, if the receiving terminal 2b is identified, the DOS attack processing unit 32 attacks the corresponding receiving terminal 2b with a D0S attack. Is performed. The DOS attack is to transmit a predetermined signal so as to increase the processing load on the receiving terminal 2b, which makes it impossible for the receiving terminal 2b to normally receive the multicast data. With such a method, unauthorized reception at the receiving terminal 2b can be prevented by a simple method without particularly changing the existing network configuration.

When multicast data is distributed on the IP network, as shown in FIG. 1, the multicast data from the server 1 is transmitted in units of the sub-networks 12 constituting the network 11. Specifically, the multicast data is transmitted to the relay device 4 that relays the data to each node in the sub-network 12. The relay device 4 is realized, for example, as a router or a combination of a router and a switching hub.

In the sub-network 12 under the relay device 4, a reception request signal for requesting the relay device 4 to receive the multicast data at each of the receiving terminals 2a and 2b, and stopping the reception by the relay device Communication is performed using a reception stop notification signal to be notified to the relay device 4 and an inquiry signal for requesting the relay device 4 to transmit these signals and inquiring about the reception status of each of the receiving terminals 2a and 2b. These signals are transmitted to all nodes in the sub-network 12 via the relay device 4.

Here, a basic operation in such a distribution system will be described.

First, the server 1 transmits multicast data by designating the sub-network 12 (step S 1). As a result, the multicast data is transmitted to the relay device 4.

In the sub-network 12, the relay device 4 sends a multicast message to each of the receiving terminals 2 a and 2 b in response to the reception request signal and the reception stop notification signal transmitted from each of the receiving terminals 2 a and 2 b. Transmission is controlled. For example, when the receiving terminal 2a transmits a reception request signal on the sub-network 12 by specifying identification information for identifying the multicast data (step S2-1), the reception request The relay device 4 that has received the signal relays the multicast data from the server 1 to the receiving terminal 2a (Step S2-2). Thus, the receiving terminal 2a receives the multicast data.

Thereafter, an inquiry signal for inquiring the reception state is transmitted from the relay device 4 to the sub-network 12 periodically, and the receiving terminal 2a that has received the inquiry signal sends a reception request signal as a response. By transmitting, reception of the multicast data is continued. When the reception stop notification signal is transmitted from the receiving terminal 2a, transmission of the multicast data from the relay device 4 to the receiving terminal 2a is stopped. Such a communication procedure is specified in, for example, IGMP (Internet Group Management Protocol).

By the way, as described above, these reception request signal, reception stop notification signal, and inquiry signal are transmitted to all nodes in the subnetwork 12. Therefore, when the unauthorized reception prevention device 3 is connected to the sub-network 12 under the relay device 4, the unauthorized reception prevention device 3 receives these signals and receives the multicast data. Terminals 2a and 2b can be specified.

Here, an operation for preventing unauthorized reception in this distribution system will be described.

First, each of the receiving terminals 2a and 2b registers in advance information such as a network address and a desired reception period of multicast data. Thereby, the authentication information 3a is generated. Further, by this registration, each of the receiving terminals 2a and 2b obtains identification information for identifying the multicast data.

The distribution of the multicast data is performed normally by the above-described procedure. Here, for example, if the receiving terminal 2b has learned the identification information of the multicast data, the receiving terminal 2b specifies the identification information and transmits a reception request signal (step S3). — 1), the multicast data is transmitted from the relay device 4 that has received the reception request signal to the receiving terminal 2 b (step S 3-2).

By the way, since the reception request signal from the receiving terminal 2b is transmitted to all nodes in the subnetwork 12, it is also received by the unauthorized reception prevention device 3 (step S3-3). The unauthorized reception prevention device 3 specifies the source receiving terminal 2b from the received reception request signal. Then, by the processing of the determination unit 31, the authentication information 3a is referred to to determine whether the receiving terminal 2b is permitted to receive. If it is determined by this determination that the receiving terminal 2 b is performing unauthorized reception (step S 4), the processing of the DOS attack processing unit 32 causes the receiving terminal 2 b to pass through the sub-network 12. A DOS attack is performed on b (step S5).

This DOS attack is performed, for example, by issuing a command for checking whether or not a signal has reached a destination on a predetermined network layer based on a response to the transmitted signal. For example, a PING command can be used as such a command. Then, for example, until the response time from the receiving terminal 2b to the command issuance becomes longer, the transmission data amount is gradually increased and the execution is repeatedly performed. Thereafter, the transmission data amount is appropriately increased, and the reception stop notification signal is transmitted from the reception terminal 2b, or the reception terminal 2b responds to the periodic inquiry signal from the relay device 4. Continue the DOS attack until it stops. As a result, in the receiving terminal 2b, the received signal increases, the processing load increases, and it becomes impossible to normally receive the multicast data. Therefore, illegal reception of multicast data is prevented.

In the above distribution system, the provision of the unauthorized reception prevention device 3 identifies the receiving terminal that is receiving multicast data illegally within the range of the existing network configuration and communication procedure, and uses a DOS attack. Thus, only the target receiving terminal can be set to a state in which multicast data cannot be received. Therefore, for example, illegal reception of multicast data can be prevented by a simple method without increasing the processing load on a server or a legitimate receiving terminal by encrypting the multicast data itself.

Next, embodiments of the present invention will be specifically described. Here, a case will be described in which the present invention is applied to a distribution system that distributes multicast data through the Internet. In this example, it is assumed that the network technology follows the Internet Protocol (IP).

FIG. 2 is a diagram illustrating an example of a system configuration according to the embodiment of the present invention. The distribution system shown in FIG. 2 includes a distribution server 100 that distributes the contents of multicast data, an authentication server 200 that authenticates a recipient, and a plurality of receiving terminals 300 that receive the distributed content. a, 300b, and 300c, and an unauthorized reception prevention device 400 that performs processing for preventing unauthorized reception. These devices are connected by an IP network 500.

The IP network 500 is a network in which a plurality of sub-networks are interconnected by a router. The distribution server 100 is connected to the IP network 500 via a switching hub (SW-Hub) 511 and a router 512. Similarly, the authentication server 200 is also connected to the IP network 500 via the switching hub 52 1 and the router 52 2. The receiving terminals 300a to 300c and the unauthorized reception preventing device 400 are connected to a switcher hub 531, respectively. It is connected to the IP network 500 via 3 2.

Each of the routers 5 12, 5 2 2 and 5 32 is a multicast router that supports routing of multicast data as well as multicast data. Under the router 532, a sub-network 501 identified by the multicast group address is configured. Then, communication according to IGMP is performed between the nodes in the subnetwork 501.

The distribution server 100 transmits, for example, a content such as a moving image stream to the IP network 500 as IP multicast data at a specified time. At this time, distribution is performed by specifying the multicast group address corresponding to each content.

The authentication server 200 is used by the content receiver to register for reception.

Functions as a web server. In the authentication server 200, reception registration of content corresponding to a plurality of multicast group addresses is performed. Then, necessary information among the registered recipient information is distributed to the unauthorized reception preventing device 400 as needed. In addition, based on the information notification from the unauthorized reception prevention device 400, each The receiving state of the content in each receiving terminal corresponding to the content is managed. The receiving terminals 300a to 300c are terminal devices that receive content, and are realized, for example, as PCs (personal computers). When the receiver accesses the authentication server 200 and registers for receiving the content, the receiver obtains a multicast group address corresponding to the content together with information on the date and time of distribution. By specifying this multicast group address at the time of reception, it is possible to receive desired content.

The unauthorized reception prevention device 400 has a processing function of receiving a message conforming to the IGMP (hereinafter, abbreviated as the IGMP message), and based on the IGMP message, a receiving terminal in the sub-network 501. It manages the content reception status in 300a to 300c. Then, based on the recipient information received from the authentication server 200, the receiving terminal that is receiving the message illegally is specified, and a DOS attack is performed on the receiving terminal.

Here, in the sub-network 501 under the control of the router 532, a multicast group corresponding to the content is formed based on a content reception request from each of the receiving terminals 300a to 300c. Such a sub-network 501 is called a broadcast domain, and the content from the distribution server 100 is routed to the router 532 based on the corresponding multicast group address.

On the other hand, in the subnet 501 under the router 532, an IGMP message is transmitted and received between each of the receiving terminals 300a to 300c and the multicast router 532. The switching hub 531 has a processing function for so-called IGMP snooping that monitors host participation / non-participation in a multicast group based on IGMP messages. ) Only the receiving terminals 300a to 300c that have issued a content reception request by packet are controlled to pass the content from the multicast router 532. In addition, the router 532 is connected to the router port of the switching hub 531, and the GMP message is set to pass unconditionally through the switching hub 531. The GMP message is transmitted to all transmission paths in the sub-network 501 via the network 532.

The IP network 500 has a broadcast

A plurality may be provided through the evening.

One or more correct reception prevention devices must be provided in each broadcast domain. Further, in the subnet 501, a plurality of switching hubs having a multicast router corresponding to IGMP and a processing function of IGMP snooping may be further provided.

Next, an example of a hardware configuration of main components in this distribution system will be described. FIG. 3 is a diagram showing an example of a hardware configuration of the unauthorized reception prevention device 400 used in the embodiment of the present invention.

As shown in FIG. 3, the unauthorized reception preventing device 400 includes a CPU (Central Processing Unit) 401, a RAM (Random Access Memory) 402, an HDD (Hard Disk Drive) 403, a graphic processing unit 404, an input I / F (interface). 1) It is composed of 405 and a communication I / F 406, which are interconnected via a bus 407.

The CPU 401 controls the entire unauthorized reception preventing device 400. The RAM 402 temporarily stores at least a part of a program executed by the CPU 401 and various data necessary for processing by the program. The HDD 403 stores an operating system (OS), application programs, and various data.

A monitor 404a is connected to the graphic processing unit 404. The graphic processing unit 404 displays an image on the screen of the monitor 404a according to a command from the CPU 401. A keyboard 405a and a mouse 405b are connected to the input IZF 405. The input IZF 450 transmits signals from the keyboard 405 a and the mouse 405 b to the CPU 401 via the bus 407. The communication IZF 406 is connected to a cable connected to the switching hub 531 and transmits and receives data to and from another computer via this cable. With the above hardware configuration, the processing functions of the present embodiment can be realized. Although FIG. 3 shows an example of the hardware configuration of the unauthorized reception prevention device 400, the distribution server 100, the authentication server 200, and the receiving terminals 300a to 300c also It can be realized by a similar hardware configuration.

Next, a basic operation of the distribution system when distribution data is distributed will be described with reference to FIG.

First, at the time of content distribution, a multicast group address corresponding to the content requested to be received is notified to each of the receiving terminals 300a to 300c in advance. This notification is performed based on advance registration from the receiving terminals 300a to 300c to the authentication server 200, as described later.

The content is transmitted from the distribution server 100 with the corresponding multicast group address specified in the IP packet. This content will be routed to the address 5232 based on the specified multicast group address.

532 monitors the IGMP messages from the receiving terminals 300a to 300c. Then, if there is at least one receiving terminal issuing a content reception request using an IGMP—HMR packet, the content from the distribution server 100 is transmitted to the subnetwork 501 under the subordinate network. I do. Switching hub 531, based on the IP multicast address included in the IGMP—HMR bucket, passes the content from router 531 to the source receiving terminal. As a result, the content is received at the receiving terminal that has issued the reception request.

Also, the receiving terminals 300a to 300c periodically issue an I GM P—HMR bucket during the reception of the content, so that each of the receiving terminals 300a to 300c. The reception of the content is continued. When the receiving terminals 300a to 300c stop receiving the content, the receiving terminals 300a to 300c issue an IGMP-1eaVe bucket to notify the reception stop. The switching hub 531 blocks the transmission of the content to the receiving terminal that is the source of the IGMP-1 eave packet. In addition, the router 532 issues a reception request within the subnetwork 501 under the router. If there is no receiving terminal present, routing of the content into the sub-network 501 is stopped.

It should be noted that the I GM P—HM R bucket and the I GM P—1 eave packet are independently issued from each of the receiving terminals 300 a to 300 c and between the I GM P—HM R bucket and the I In some cases, each of the receiving terminals 300a to 300c is issued as a response to GMP-HMQ (Host Membership Query).

Next, in such a distribution system, a function of preventing unauthorized reception of content at the receiving terminals 300a to 300c will be described in detail. The function of preventing unauthorized reception is realized by the processing of the authentication server 200 and the unauthorized reception prevention device 400.

First, the processing function of the authentication server 200 will be described. FIG. 4 is a block diagram showing functions of the authentication server 200.

As shown in FIG. 4, the authentication server 200 stores a recipient information management DB (data storage database) that stores information on recipients who receive content using the receiving terminals 300a to 300c. Base) 210, a WWW server unit 220 that provides a Web site for registering recipient information, and an information registration processing unit 2 that performs information registration processing for the recipient information management DB 210 30 and a receiver information distribution unit 240 for distributing receiver information to the unauthorized reception prevention device 400 and the unauthorized reception prevention device 400 From the respective receiving terminals 300 to 300 The status notification receiving unit 250 receives a notification of the content reception status at 0c.

In the recipient information management DB 210, personal information such as the name and address of the recipient, information identifying the content desired to be received, an ID and password for authentication, and the receiving status of the content of each recipient are stored. Be managed. This recipient information will be described in detail in FIG.

The WWW server unit 220 performs a process of providing a Web site for the receiver to apply for the reception of the content through the IP network 500. Specifically, after receiving access from each of the receiving terminals 300a to 300c via unicast communication, a screen for registering various information and inputting the content desired to be received is provided to the receiver. Then, the input information is output to the information registration processing section 230. Also this When the information registration is normally performed, the multicast group address corresponding to the content is received from the information registration processing unit 230 and notified to the receiver.

The information registration processing unit 230 registers the recipient information received from the WWW server unit 220 in the recipient information management DB 210. At the time of this registration, authentication processing is performed as necessary. Further, the registered receiver information is output to the receiver information distribution unit 240, and is transmitted to the unauthorized reception prevention device 400 connected to the subnetwork 501 corresponding to the multicast group address. It should be noted that the latest receiver information corresponding to a certain multicast group address is periodically searched from the receiver information management DB 210 and transmitted to the corresponding unauthorized reception prevention device 400 through the receiver information distribution unit 240. It may be transmitted.

Further, information registration processing section 230 receives information indicating the current reception state of the content of the receiver from state notification receiving section 250, and updates receiver information management DB 210.

The receiver information distribution unit 240 transmits the receiver information passed from the information registration processing unit 230 to the unauthorized reception prevention device 400 corresponding to the multicast group address in the receiver information by IP. It is transmitted by unicast communication through the network 500.

The status notification receiving section 250 sends information indicating whether or not the content is received at each of the receiving terminals 300a to 300c, and whether or not the reception is unauthorized, to the The data is received from the reception prevention device 400 by unicast communication and output to the information registration processing unit 230.

FIG. 5 is a diagram showing a format of the recipient information stored in the recipient information management DB 210.

As shown in Fig. 5, the recipient information includes the recipient ID and password used to log in to the authentication server 200 when registering and changing the information, and the receiving terminal 3 The IP addresses (unicast just addresses) of 00a to 300c and the sender IDs for identifying these receiving terminals 300a to 300c are recorded. In addition to these, the content for which The corresponding multicast group address and the expiration date indicating the expiration date on which this content can be received are recorded. The above information is generated and stored based on the access from each of the receiving terminals 300a to 300c.

Further, the receiver information includes a reception state flag indicating whether or not the corresponding content is currently received at each of the receiving terminals 300a to 300c, and whether the reception is invalid. An unauthorized reception flag indicating whether or not the message is stored is stored. These pieces of information are updated based on information transmitted from the unauthorized reception prevention device 400. These pieces of recipient information are stored for each recipient and for each multicast group address corresponding to the content desired to be received. Also, for example, it is kept for a certain period of time even after the usage period has expired, and is deleted when there is a request from the recipient to delete registered information.

Next, the processing function of the unauthorized reception prevention device 400 will be described. FIG. 6 is a block diagram showing functions of the unauthorized reception prevention device 400.

As shown in FIG. 6, the unauthorized reception prevention device 400 is transmitted from the recipient information management DB 410 storing the recipient information in the subnet mask 501 and the authentication server 200. Information updating unit 420 that updates the recipient information management DB 410 based on the information received and the receiving state of the content at each of the receiving terminals 300 a to 300 c. Status notification unit 4300 that notifies the IGP message transmitted to the subnetwork 501, and the IGMP message reception unit 4400 that receives the IGP message, and the registration information of the receiver information management DB 410 It is composed of a receiver management processor 450 that manages recipients based on the information, and a DOS attack processor 450 that performs a DOS attack on a receiving terminal that is illegally receiving content.

Reception information management DB 410 stores reception information using reception terminals 300 a to 300 c provided in sub-network 501 out of the reception information managed by authentication server 200. Only the information of the person is stored. Specifically, for example, of the recipient information shown in FIG. 5, all information except the password is stored.

The receiver information updating unit 420 registers and updates the receiver information received by the unicast communication from the authentication server 200 in the receiver information management DB 410. The reception status notifying section 4300 receives the content at the receiving terminals 300a to 300c. Information indicating the status is received from the receiver management processing unit 450 and transmitted to the authentication server 200 by unicast communication.

The IGMP message receiving unit 440 receives and analyzes the IGMP message transmitted to the subnetwork 501, and analyzes the analysis result as a recipient management processing unit 450 and a DOS attack processing unit. Notify 460.

The receiver management processing unit 450 receives the analysis result of the IGP message from the IGP message receiving unit 450 and receives the content at each of the receiving terminals 300a to 300c. The state is grasped, the receiver information of the corresponding receiver is extracted from the receiver information management DB 410, and the reception state flag is updated.

Further, based on the recipient information, it is determined whether or not the receiving terminals 300a to 300c receiving the content are permitted to receive the content. Then, if it is determined that the data is received illegally, this is notified to the DOS attack processing unit 460 together with the IP address of the corresponding receiving terminal, and the unauthorized reception flag of the receiver information is updated. . Further, when the reception status flag and the illegal reception flag are updated, the updated information is output to the reception status notifying section 430 and transmitted to the authentication server 200.

Further, when the reception of the content is stopped at each of the receiving terminals 300a to 300c, the notification of this is received from the IGMP message receiving unit 440, and the corresponding receiver information is received. Update the reception status flag and the incorrect reception flag. Then, the updated information is output to the reception status notifying section 430 and transmitted to the authentication server 200.

The DOS attack processing unit 450 receives the IP address of the receiving terminal when the presence of the receiving terminal that is illegally receiving the content is confirmed by the receiver management processing unit 450. Then, a DOS attack is performed on the receiving terminal through the subnet mask 501 to increase the processing load on the receiving terminal. This DOS attack uses a PING command to confirm whether data has reached the destination on the IP layer, generates an IP bucket with a predetermined capacity, and receives data during unauthorized reception. This is performed by transmitting to the terminal. This transmission data is transmitted to the receiving terminal to the extent that deadlock or hang-up does not occur. Sent while gradually increasing the amount of data stored in P packets and the number of command issuances.

While the DOS attack processing unit 460 continues the DOS attack, the IGMP message receiving unit 440 notifies the receiving state of the content at the corresponding receiving terminal. Then, the receiving terminal transmits an I GMP—1 ea Ve packet, or the receiving terminal does not respond to the I GMP—HMQ from the router 532 for a certain period of time. The DOS attack is continued until the reception stop is notified from the IG MP message receiving unit 440. The details of the DOS attack process will be described later with reference to FIG.

Next, the operation of the distribution system when the authentication server 200 and the unauthorized reception prevention device 400 are used will be described. '

First, as described above, the authentication server 200 receives the information of the receiver and the information on the content desired to be received from each of the receiving terminals 300a to 300c, and stores them in the reception information management DB 210. . Also, the latest registration information is distributed to the unauthorized reception preventing device 400 provided in the subnet mask 501 corresponding to the content, and the receiving terminals 300 a to 300 c are transmitted from the unauthorized reception preventing device 400. It receives and manages the content reception status of the content. Communication between the authentication server 200 and each of the receiving terminals 300a to 300c and the unauthorized reception preventing device 400 is performed by a unicast communication. When content to be newly distributed in distribution server 100 is determined, a multicast group address corresponding to the content is input to authentication server 200. On the other hand, since the unauthorized reception preventing device 400 is not registered as this device in the initial state, it logs in to the authentication server 200 and receives the notification of the corresponding multicast group address.

FIG. 7 is a flowchart showing the flow of registration / update processing of recipient information in authentication server 200.

FIG. 7 shows a process in a case where, for example, the receiving terminal 300a accesses the Web page provided by the WWW super-unit 220. In step S701, new registration or registration change of the receiver's own information among the receiver information Is determined, and if these are performed, the process proceeds to step S702, and if other information is registered, the process proceeds to step S706.

In step S702, the information input at receiving terminal 300a is received. At this time, if the information that has already been registered is to be changed, the receiver ID and password are input, the information registration processing unit 230 performs authentication processing, and then receives the information to be registered.

In step S703, the information registration processing unit 230 determines whether registration of the received information in the recipient information management DB 210 is permitted. Here, for example, the eligibility of the recipient (age restriction, etc.) according to certain criteria is determined from the attributes of the recipient, whether all the necessary information has been entered, and so on. Go to 0 4. If the registration is not permitted, the WWW server unit 220 notifies the receiver that the registration is not permitted, or instructs the receiver to re-enter the information, and terminates the process.

In step S704, the registration information of the recipient information management DB 210 is updated using the received information. In step S705, when the content is specified in the above registration, the information updated at this time is transmitted to the corresponding unauthorized reception prevention device 400 by the receiver information distribution unit 240. To deliver.

Also, in step S706, it is determined whether or not the content reception is desired and whether or not the content is to be changed. If these are performed, the process proceeds to step S707, and if not, the process ends.

In step S707, a recipient authentication process is performed. Here, the receiver ID and password are input from the receiving terminal 300a, and the information registration processing unit 230 refers to the registration information of the receiver information management DB 210 to refer to the input information. Perform a match. Then, when the authentication is correctly performed, the process proceeds to step S708. If the authentication is not successful, the WWW server unit 220 notifies the recipient that the authentication is not successful, for example, and terminates the processing.

In step S 708, the information of the request for receiving the content or the request for the change is received from the receiving terminal 300 a and output to the information registration processing section 230. Then, the process proceeds to step S704, and the receiver information management DB 210 is used by using these pieces of information. , And distributes the information to the corresponding unauthorized reception prevention device 400.

Note that, for example, the recipient information distribution unit 240 may distribute new registration information in the recipient information management DB 210 to the unauthorized reception prevention device 400 at regular intervals. Further, this information distribution may be performed in response to access from the unauthorized reception prevention device 400 at regular intervals. In these cases, for example, the information registration processing unit 230 holds a flag indicating whether or not the registration information has been changed in the receiver in the broadcast domain corresponding to each multicast group address. Then, when this flag is set when the distribution is performed by the recipient information distribution unit 240, the information registration processing unit 230 extracts the corresponding registration information from the recipient information management DB 210. Then, the information may be output to the receiver information distribution unit 240 and the distribution may be performed only to the corresponding unauthorized reception prevention device 400.

In addition, information indicating the reception status of the content at each of the receiving terminals 300a to 300c is transmitted from the unauthorized reception prevention device 400 as needed by the processing of the reception status notification unit 4300. . The authentication server 200 receives this information in the status notification receiving unit 250, and updates the receiving status flag and the illegal reception flag in the recipient information management DB 210 through the information registration processing unit 230. I do.

Next, an operation for preventing illegal reception of content in subnetwork 501 will be described.

As described above, from the authentication server 200, the receiver information corresponding to the receiving terminals 300a to 300c in the subnetwork 501 is transmitted to the unauthorized reception preventing device 400. Sent at any time. In the unauthorized reception preventing apparatus 400, the receiver information updating section 420 receives this receiver information and updates the registration information of the receiver information management DB 410. Alternatively, the unauthorized reception prevention device 400 may periodically access the authentication server 200 to request transmission of the latest recipient information. By such processing, the unauthorized reception preventing apparatus 400 always keeps the latest information on necessary recipient information.

By the way, as described above, in the sub-network 501, the IGM P-in which the multicast group address is specified from each of the receiving terminals 300a to 300c When the HMR packet is transmitted, the switching hub 531 transmits the corresponding multicast data to each receiving terminal 300 according to the packet. Thus, the content is received at each of the receiving terminals 300a to 300c. Also, when each receiving terminal 300 & to 300 300 1 GMP_1 eave bucket is transmitted, the switching hub 531 stops transmission of the multicast data to the corresponding receiving terminal according to this packet. As a result, the reception of the content by each of the receiving terminals 300a to 300c is stopped.

The IGMP message is transmitted to all the nodes within the sub-network 501 through the router 532 and the switching hub 531. Therefore, by receiving the IGMP message transmitted from each of the receiving terminals 300a to 300c, the unauthorized reception preventing device 400 can know the reception status of the content at each of the receiving terminals 300a to 300c. it can. Then, based on the latest recipient information obtained from the authentication server 200, the receiving terminal in the subnet network 501 that is illegally receiving the content is identified so that the content cannot be normally received. Perform a DOS attack on the receiving terminal.

FIG. 8 is a flowchart showing the flow of the unauthorized reception prevention process in the unauthorized reception prevention device 400.

FIG. 8 shows the flow of processing when one IGMP message is received from the corresponding receiving terminal (here, receiving terminal 300c as an example) in IGMP message receiving section 440. .

In step S801, the IGMP message receiving unit 440 analyzes the received IGMP message and determines whether or not the received packet is an IGMP-HMR bucket. IGMP—If the packet is an HMR packet, go to step S802; otherwise, go to step S807.

When receiving the IGMP-HMR packet, the IGMP message receiving unit 440 notifies the receiver management processing unit 450 of the transmission of the reception request for the content from the receiving terminal 300c. At this time, the IP address of the transmission source is extracted from the received packet and notified to the receiver management processing unit 450.

In step S802, the recipient management processing unit 450 With reference to B410, the receiver information of the corresponding receiver is extracted based on the IP address, and it is determined whether the reception of the content is currently permitted. If it is permitted, the process proceeds to step S803, and "1" is set to the reception status flag in the corresponding receiver information. Further, in step S804, the reception status notifying section 430 notifies the authentication server 200 of the recipient information updated in step S803.

On the other hand, if it is determined in step S802 that the receiving terminal 300c is not permitted to receive the content, the process proceeds to step S805, and the receiver management processing unit 450 determines the reception status in the corresponding receiver information. Set "1" to both the flag and the illegal reception flag. Then, in step S806, the DOS attack processing unit 460 is instructed to perform a DOS attack on the receiving terminal 300c.

Also, in step S807, the IGMP message receiving section 440 determines whether or not the received IGMP message is an IGMP-1eaVe bucket. It is determined whether or not the packet is an IGMP—HMR packet. If the packet is an IGMP—leaVe bucket, the process proceeds to step S808; otherwise, the process ends. When the IGMP message receiving unit 440 receives the IGMP-1eaV e bucket, the IGMP message receiving unit 440 sends a request to stop receiving the content from the receiving terminal 300c to the receiver management processing unit 450 as described above. At the same time, the IP address of the transmission source is notified to the receiver management processing unit 450.

In step S808, the receiver management processing unit 450 extracts an unauthorized reception flag from the corresponding receiver information in the receiver information management DB 410, and determines whether or not this flag is "1". If the flag is not "1", that is, if the flag is "0", it means that the receiving terminal 300c has normally received the content, and the process advances to step S809 to set the receiving status flag 809 to "0". "Back to. Then, the process proceeds to step S804, where the reception status notifying unit 430 notifies the authentication server 200 of the updated recipient information.

If the unauthorized reception flag is “1” in step S808, it means that the unauthorized reception of the content at the receiving terminal 300c has been stopped, and the receiver management process is performed. The control unit 450 returns both the reception status flag and the illegal reception flag in the corresponding receiver information to “0”. Then, in step S811, it instructs the DOS attack processing unit 460 to stop the DOS attack on the receiving terminal 300c.

In the sub-network 501, the router 532 sends IGMP-HMQ packets to the receiving terminals 300a to 300c at regular intervals to monitor the status of participation in the multicast group and non-participation in the multicast group. . Each of the receiving terminals 300a to 300c usually transmits an IGMP message in response to the IGMP-HMQ packet.

When the reception status flag is "1" and the reception terminal 300c does not receive the IGMP message for a certain period of time or longer, the unauthorized reception prevention device 400 stops receiving the content at the reception terminal 300c. Judge that Specifically, similarly to the processing in steps S808 to S811 in FIG. 8, when the receiving terminal 300c is performing normal reception, the reception state flag is updated. If the receiving terminal 300c is receiving an unauthorized message, the receiving terminal 300c updates both the receiving status flag and the illegal receiving flag and stops the DOS attack.

Next, DOS attack processing in the DOS attack processing unit 460 will be described in detail. FIG. 9 is a flowchart showing the flow of the DOS attack process.

In the DOS attack processing section 460, when the receiver management processing section 450 first instructs the receiving terminal 300c to perform a DOS attack (corresponding to step S806 in FIG. 8), Of the flowchart of FIG. This process is performed in parallel with the process of receiving the I GMP message in the I GMP message receiving unit 440, and the receiving terminal 300c stops the illegal reception, and the receiver management processing unit 450 instructs to stop the DOS attack. (Corresponding to step S811 in FIG. 8).

In step S901, a PING command in which a predetermined amount of data is stored in a bucket is continuously issued at regular intervals to the receiving terminal 300c that is performing illegal reception of content. Here, the initial values of the data volume and command issuance are particularly affected by the processing at each of the receiving terminals 300a to 300c. Set each value so that there is no effect.

In step S902, the receiving terminal 3 for the issued PING command

Measure the response time from 0 0 c. Then, this measured value is held as the initial response time.

In step S903, the amount of data stored in the packet is increased from that at the time of the previous issuance, the command issuance interval is shortened, and the issuance of the PING command is continued. Here, for example, an appropriate value (m, n) larger than 1 is set, the command issuance interval is set to l Zm times that of the previous issue, and the amount of data for one command issuance is set at the time of the previous issue. N times.

In step S904, it is determined whether the response time from the receiving terminal 300c has increased. If not, the process returns to step S903 to further strengthen the DOS attack. Thereafter, the DOS attack is continued while gradually increasing the intensity until the response time changes, and if the response time increases by a predetermined value or more, the process proceeds to step S905.

In step S905, while maintaining the data amount and the command issue interval, P

Continue issuing the 1 NG command. Then, in step S906, it is determined whether or not a signal instructing to stop the DOS attack by issuing the command has been received from the receiver management processing unit 450. Then, while this signal is not received, the process returns to step S905 to continue issuing the command. At this time, while further referring to the response time from the receiving terminal 300c, the amount of data may be increased and the command issuing interval may be shortened.

Then, when an instruction to stop the DOS attack is issued from the receiver management processing unit 450, the process advances to step S907 to stop issuing the PING command.

In such DOS attack processing, the content is illegally received by gradually increasing the amount of data in the packet and continuously issuing PING commands while gradually shortening the command issue interval. The processing load on the receiving terminal 300c is gradually increased. This increase in processing load on the receiving terminal 300c is confirmed by an increase in response time to the PING command.

As the processing load increases, the receiving terminal 300c receives the content normally. Communication is interrupted. Then, receiving terminal 300c is in a state where it cannot respond to IGMP-HMQ periodically transmitted from router 532. Alternatively, when the receiving terminal 300c determines that normal reception of the content is not possible by processing of the application for receiving the content, the receiving terminal 300c automatically transmits the HGMP-1eaVe packet. Due to the occurrence of these situations, the transmission of the content to the receiving terminal 300c is stopped.

The unauthorized reception prevention device 400 detects that no response to the I GM P—HM Q has occurred or that an IGMP-1eaV e packet has been transmitted, and confirms that the unauthorized reception has been resolved. Stop DOS attacks. Even if such a situation is not detected, the strength of the DOS attack is gradually increased, so that the receiving terminal 300c cannot normally receive the content. As described above, the unauthorized reception prevention device 400 receives the IGMP message in the sub-network 501, grasps the terminal device receiving the content, and refers to the receiver information for unauthorized reception. Of the terminal device performing the communication. Then, a DOS attack is performed on this terminal device, thereby obstructing the reception of the content.

Such processing makes it possible to easily prevent illegal reception of content. In this process, since the content is not encrypted / decrypted, there is no need to perform a high-load process during transmission or reception, which is particularly suitable for distribution of images using data compression technology such as MPEG. . In addition, in order to realize this processing function, it is not necessary to change the specifications of the network devices such as the router switching unit constituting the IP network 500 at all. Therefore, it is possible to easily prevent unauthorized reception of contents using the existing network configuration, and the versatility is high, and the introduction cost of equipment is suppressed.

In addition, since the authentication server 200 manages the recipient information in the entire distribution system, the recipient is efficiently managed. At the same time, information registration and reception application for a large number of contents by a large number of recipients are performed collectively in the authentication server 200, which is convenient for the recipients. As described above, in the method for preventing unauthorized reception according to the present invention, whether or not each receiving terminal is permitted to receive the multicast data is provided as authentication information. It is registered in advance, and whether or not the receiving terminal receiving the multicast data is permitted to receive is determined based on the authentication information. Then, the processing load on the receiving terminal is increased by performing a DOS attack on the unauthorized receiving terminal that is not permitted to receive. As a result, an illegal receiving terminal cannot normally receive multicast data, and illegal reception can be easily prevented without affecting the existing network configuration. Also, since the multicast data itself is not encrypted, no burden is placed on the transmission / reception processing and reproduction processing of the multicast data.

The above merely illustrates the principles of the invention. In addition, many modifications and changes will be apparent to those skilled in the art and the present invention is not limited to the exact configuration and application illustrated and described above, but all corresponding variations and equivalents may be Claims and their equivalents are considered to be within the scope of the invention.

Claims

The scope of the claims

1. In an unauthorized reception prevention method for preventing a multicast terminal transmitted from a server onto a network from being illegally received at a receiving terminal, the method comprises the steps of: It is determined whether the receiving terminal receiving the multicast data is permitted to receive,

For the unauthorized receiving terminal that is not permitted to receive, through the network, perform a DOS (Denial Of Service) attack that transmits a predetermined signal so as to increase the processing load of the receiving terminal,

A method for preventing unauthorized reception.

2. The DOS attack is performed by issuing a command to check whether a signal has reached a destination on a predetermined network layer based on a response to a transmission signal, and the receiving terminal responds to the command issuance by the receiving terminal. 2. The method for preventing unauthorized reception according to claim 1, wherein the method is repeatedly executed by gradually increasing the transmission data amount until the response time becomes longer.

3. The multicast data from the server is transmitted to a relay device on a sub-network constituting the network, and a reception request signal for the multicast data transmitted from the receiving terminal on the subnetwork is transmitted to the relay device. When transmitted to all nodes on the subnet network, a communication system is configured in which the multicast data is relayed from the relay device that has received the reception request signal to the receiving terminal that has requested reception. If you have

Receiving the reception request signal through the sub-network, and determining, based on the authentication information, that the reception terminal of the reception request source is incorrect, the DOS through the sub-network to the reception terminal of the reception request source; 2. The method for preventing unauthorized reception according to claim 1, wherein an attack is performed.

4. In the DOS attack, the transmission of the reception request signal from the unauthorized receiving terminal is stopped until a notification signal notifying that the reception of the multicast data is stopped is transmitted from the unauthorized receiving terminal. Until it is repeatedly executed. 4. The method for preventing unauthorized reception according to claim 3, wherein

5. The method according to claim 1, wherein the authentication information includes information indicating a period during which the receiving terminal is permitted to receive the multicast data.

6. In a data distribution system where multicast data is distributed to users through a network,

A server having a data transmission unit for transmitting the multicast data through the network;

A receiving terminal having a data receiving unit that receives the multicast data through the network;

A determination unit that determines whether or not the receiving terminal receiving the multicast data is permitted to receive, based on authentication information for the receiving terminal registered in advance;

A D O S attack processing unit that performs a D O S attack for transmitting a predetermined signal so as to increase the processing load of the reception terminal through the network to the unauthorized reception terminal that is not permitted to receive,

An unauthorized reception prevention device having

A data distribution system comprising:

7. In a data distribution system in which multicast data is distributed in units of sub-networks,

A server having a data transmission unit for transmitting the multicast data over the network by designating the sub-network;

A reception request unit for transmitting a reception request signal for the multicast data on the sub-network;

A data receiving unit that receives the multicast data transmitted on the sub-network in response to the reception request signal;

A receiving terminal having

A first request signal receiving unit that receives the reception request signal through the sub-network; A data relay unit that relays just

A network relay device having

A second request signal receiving unit that receives the reception request signal through the sub-network,

Based on authentication information for the receiving terminal registered in advance, a receiver determining unit that determines whether the receiving terminal of the receiving request source is permitted to receive the multicast data,

A DOS attack processing unit that performs a DOS attack for transmitting a predetermined signal to the unauthorized reception terminal that is not permitted to receive, through the subnetwork so as to increase a processing load of the reception terminal,

An unauthorized reception prevention device having

A data distribution system comprising:

8. In an unauthorized reception prevention device for preventing multicast data transmitted from a server from being illegally received by a receiving terminal connected to the server via a network,

For the unauthorized receiving terminal that is not permitted to receive, through the network, a DOS attack processing unit that performs a DOS attack that transmits a predetermined signal so as to increase the processing load of the receiving terminal,

An unauthorized reception prevention device comprising:

9. The multicast data from the server is transmitted to the relay device on the sub-network constituting the network, and the reception request signal for the multicast data transmitted from the receiving terminal on the subnet is transmitted. When transmitted to all nodes on the sub-network, in the communication system in which the multicast data is relayed from the relay device that has received the reception request signal to the receiving terminal that is the source of the reception request, the multicast An unauthorized reception prevention device for preventing data from being illegally received at the receiving terminal, A request signal receiving unit that receives the reception request signal through the sub-network;

An unauthorized reception prevention device comprising: