Patent Application
20240187428
The present invention relates to a technology for switching a Pub to be handled with priority on a Sub side in response to generation of unauthorized data.
In recent years, in order to implement a smart factory, devices on an information network (NW) and devices on a control NW are connected. In the future, a communication model that performs device interconnection and one-to-many, many-to-one communication in a lightweight and flexible manner is expected to be widespread.
A Publish/Subscribe communication (hereinafter, Pub/Sub communication) model has been proposed as a lightweight and flexible communication model as described above. In Pub/Sub communication, there are a Publisher, which is a client on a side on which a message called an event is created and transmitted (distributed), and a Subscriber, which is a client on a side on which the message is received (subscribed).
The Pub/sub communication has three properties of “spatial separation”, “temporal separation”, and “asynchronous processing”. Due to the “spatial separation”, the Publisher and the Subscriber do not need to know existence of each other. The “temporal separation” enables transmission and reception of data even in a case where the Publisher and the Subscriber do not exist on the network at the same time. Furthermore, by the “asynchronous processing”, transmission and reception of an event can be performed asynchronously with other processing of the Publisher or the Subscriber.
The Pub/Sub communication model includes a broker type and a broker-less type. The configuration of the broker type is a configuration in which functions called a broker responsible for properties of the spatial separation, the temporal separation, and the asynchronous processing is arranged between the Pub and the Sub. The configuration of the broker-less type is a distributed configuration in which all nodes (Pub and Sub) include functions responsible for the properties of the spatial separation, the temporal separation, and the asynchronous processing. By providing a function called data distribution service (DDS) in each of the nodes, the above-described broker-less type configuration can be implemented. Note that the Pub/Sub communication model is also referred to as a publishing/subscribing model.
Non-Patent Literature 1: What's in the DDS Standard, Internet <URL: https://www.dds-foundation.org/omg-dds-standard/>
In a communication system that performs Pub/Sub communication using the DDS, Pubs can be made redundant by a basic function of the DDS, and for example, which Pub among a plurality of the Pubs in the redundant configuration is handled as a prioritized Pub (hereinafter, priority Pub) can be automatically switched.
However, the above switching is performed in a case where a failure or the like occurs in a priority Pub and there is no communication with Subs. Therefore, in the basic function of the DDS, for example, a priority Pub cannot be automatically switched in a case where the priority Pub is taken over by a third party having an unauthorized purpose and data of unauthorized contents (for example, data for the purpose of attacking a Sub, and the like) is transmitted.
The present invention has been made in view of the above points, and an object of the present invention is to provide a technology for switching a Pub handled with priority on a Sub side in response to generation of unauthorized data in a communication system that performs Pub/Sub communication.
According to the disclosed technology, a communication system is provided that performs communication among a plurality of nodes by a broker-less type publishing/subscribing model, the communication system including:
According to the disclosed technology, a technology is provided that enables switching a Pub to be handled with priority on a Sub side in response to generation of unauthorized data in a communication system that performs Pub/Sub communication.
Hereinafter, an embodiment of the present invention (present embodiment) will be described with reference to the drawings. The embodiment described below is only an example, and an embodiment to which the present invention is applied is not limited to the following embodiment.
In the embodiment described below, an example in which the present invention is applied to a communication system that performs Pub/Sub communication using DDS will be described, but the present invention is applicable not only to the Pub/Sub communication using the DDS.
First, DDS and Pub/Sub communication using the DDS as premises of the present embodiment will be described.
In the present embodiment, the above-described broker-less type configuration is employed, and the DDS includes a function corresponding to a broker, thereby implementing the broker-less type.
Here, delivery range management in the DDS will be described. In the DDS, a delivery NW is added to an NW I/F of a node. A delivery range set by a user is operated by this delivery NW and a filter inside the DDS, and enables transmission and reception of data appropriate for an application functioning as a Pub or a Sub.
Specifically, in the DDS, based on a data bus and the delivery range set by the user, a multicast address is assigned to the NW I/F that can be used in nodes, and the delivery NW is prepared. Whether to perform distribution by unicast using an existing IP address of a node or by a newly assigned multicast address can also be set when the delivery range is designated, and thus a physical data distribution range can be defined.
The DDS is a program that functions as middleware in a node (may be referred to as a computer, a communication device, or the like). A processing program as a base necessary for communication in the DDS is prepared as a library. A DDS program can be generated using this library from a data definition file for communication program generation including, as parameters, definitions (type, size, name, QoS, and the like) of data transmitted by an application (described as “APP”) . Generation of the DDS itself is an existing technology.
A sensor is connected to each of nodes 1 and 2, and an APP that generates data to be published and the DDS are mounted on each of the nodes 1 and 2. A control valve is connected to each of nodes 2 and 3, on which an APP that uses subscribed data and the DDS are mounted.
The example of
Note that, in the example of
Hereinafter, an example will be described as an example of the technology according to the present embodiment.
Next, an example of a communication system as a base in the present example will be described. In the communication system as the base in the present example, one node may belong to a plurality of domains. Furthermore, a plurality of Pubs/Subs may exist in one node. Note that, here, the Pub is an application that generates data to be published, and the Sub is an application that uses subscribed data. The functions related to the Pub/Sub communication are performed by the DDS.
Furthermore, both a Pub/Sub may exist in one node, and a Pub/Sub across a plurality of domains may exist in one node. Furthermore, a plurality of Pubs or a plurality of Subs may exist in one APP. Furthermore, the Pubs or the Subs in the same APP can be distinguished from one another. Furthermore, in the communication system in the present example, communication is plain text.
In the example of
For example, in the node 10, a “Pub1 (APP i)” is an application for publishing data of a topic [i], and functions as a Pub1 (Publisher1) in the Pub/Sub communication. In the node 10, there are two Pubs of the Pub1 (APP i) and a Pub2 (APP i). This indicates that there is one APP but the function of the DDS enables the one APP to function as the two Pubs. The same applies to a Sub as indicated in the node 15.
Furthermore, the node 11 includes both a Pub and a Sub of a Pub3 and a Sub4. There is a plurality of APPS that functions as a plurality of Pubs in the nodes 12 and 14, and there is a plurality of APPS that functions as a plurality of Subs in the nodes 17 and 18.
Furthermore, in the communication system illustrated in
Furthermore, the Internet 55 is connected to an end of the L3SW 30, and each node can communicate with the Internet 55. Furthermore, the packet analysis device 40 is connected to the L2SWs 20 and 21, and for example, the detection unit 50 can perform anomaly detection based on a packet analysis result.
For example, a case will be considered in which, for a certain topic, there are three redundant Pubs of a first Pub, a second Pub, and a third Pub, and each of the Subs of the first Sub to the third Sub treats the first Pub as a priority Pub. In this case, data is distributed from each of the first Pub to the third Pub to each of the Subs, but only data distributed from the first Pub is transferred to APPs on a Sub side.
In a basic function of the DDS, in a case where a failure or the like occurs in the first Pub, each of the Subs can switch the priority Pub to the second Pub or the third Pub. However, as described above, in the basic function of the DDS, the priority Pub cannot be switched to the second Pub or the third Pub, for example, in a case where the first Pub is taken over by a third party and transmitting data of unauthorized contents (for example, data for the purpose of attacking a Sub, and the like).
In the present example, a mechanism is provided that enables switching a priority Pub in a case where the priority Pub is transmitting data of authorized contents (hereinafter, unauthorized data).
The configuration management unit 60 manages configuration information (NW configuration information) of the communication system, and the coping unit 70 performs processing for switching of a priority Pub in response to detection of unauthorized data by the detection unit 50. At this time, the coping unit 70 uses the configuration information to decide which Pub among the redundant Pubs is to serve as the priority Pub. Note that the detection unit 50, the configuration management unit 60, and the coping unit 70 may be included in the packet analysis device 40 or may be included in a device different from the packet analysis device 40. In the present example, it is assumed that the packet analysis device 40 includes the detection unit 50, the configuration management unit 60, and the coping unit 70.
In the configuration management unit 60, the configuration information of the communication system needs to be managed. Although the configuration information may be created and managed by any method, in the present example, the configuration information is created and managed by a plurality of items of relationship information that can be created from communication (traffic) flowing among the nodes being combined.
As the relationship information, three layers of an “IP relationship layer”, a “participant relationship layer”, and a “Pub/Sub relationship layer” representing topology of the horizontal axis of the NW are created. Since the IP relationship layer and the participant relationship layer are associated with each other, and the participant relationship layer and the Pub/Sub relationship layer are associated with each other, all the three layers are eventually associated with each other, and by combining these three layers, a “combined layer” representing topology of the vertical axis of the NW is obtained. Configuration information is managed by holding the combined layer for a plurality of generations. Note that a generation refers to, for example, a division obtained by performing division by a certain time interval, an event interval, or the like. However, holding a plurality of generations is not essential, and for example, only the latest one generation may be held.
The Pub/Sub relationship layer can be created using information acquired from communication as data distribution, and the participant relationship layer can be created using information acquired from communication for DDS operation. Meanwhile, the IP relationship layer can be created using information acquired from both communication as data distribution and communication for DDS operation. Note that the communication for DDS operation is communication performed in a case where a node participates in the Pub/Sub communication; communication performed in a case where another node is searched for; communication performed in a case where distribution contents are agreed; and the like.
In the IP relationship layer, one vertex is associated with a 5-tuple including an IP address of a node (src/dst IP addresses, src/dst port numbers, protocol number). In the participant relationship layer, a GUID and a port number are associated with one symbol (triangular or inverted triangular symbol). In the Pub/Sub relationship layer, a GUID and a topic name are associated with one vertex. The GUID is an identifier used in the DDS, and is generated from an IP address, a port number, and the like. Note that one node may include a plurality of GUIDs (for example, in a case where one node functions as both a Pub and a Sub; in a case where one node belongs to a plurality of domains or a plurality of topics; and the like).
Therefore, the IP relationship layer can be associated with the participant relationship layer using port numbers, and the participant relationship layer can be associated with the Pub/Sub relationship layer using GUIDs. By combining the three layers being combined by these associations, the combined layer is obtained as the NW configuration information of the communication system that performs Pub/Sub communication. This combined layer is held, for example, for a plurality of generations.
Here, in a case of focusing on one node in the combined layer, one or more vertices of the IP relationship layer (5-tuple including IP addresses) correspond to this node, and one or more vertices of the participant relationship layer (port numbers and GUIDs) are associated with the one or more vertices. Furthermore, zero or more vertices of the Pub/Sub relationship layer (GUIDs and topic names) are associated with the one or more vertices of the participant relationship layer. That is, in the combined layer, for each node, a tree structure having the node as a vertex (a tree structure in which the highest hierarchy level represents the IP address, the next hierarchy level represents the port number, the next hierarchy level represent the GUID, and the lowest hierarchy level represents the topic name) is obtained, and the tree structure represents vertical axis topology.
In the present example, a mechanism is provided that enables switching a priority Pub in a case where the priority Pub is transmitting unauthorized data using the above configuration information.
In the present example, the above units detect generation of unauthorized data, and switch a Pub to be handled with priority on a Sub side in response to the detection.
Next, an operation example of the communication system in the present example will be described with reference to a sequence diagram of
The unauthorized data generation detection unit 510 detects generation of unauthorized data and a location of generation (that is, a Pub that has transmitted the unauthorized data) in the communication system (S101). The unauthorized data is data of unauthorized contents (that is, data of originally unintended contents). Examples of the unauthorized data include data that is transmitted by a Pub taken over by a malicious third party and is for the purpose of attacking a Sub, data of numeral values in a range in which transmission cannot be originally performed by Pub side APPs, data of contents that cannot be normally recognized even if received by Sub side APPs, and the like. Such detection of generation of unauthorized data and the location of generation are performed by an existing technology.
The unauthorized data generation detection unit 510 notifies the switching possibility selection unit 710 of the location of generation of the unauthorized data (that is, a Pub that has transmitted the unauthorized data) (S102). The switching possibility selection unit 710 searches in the switching possibility selection condition recording unit 730 for a switching condition based on the location of generation, and acquires the switching condition as a search result (S103 to S104).
Here, the switching possibility selection condition recording unit 730 records switching conditions for switching a Pub transmitting unauthorized data to another Pub in the redundant configuration. Such switching conditions may be recorded, for example, for each Pub, may be recorded for each domain or topic, or may be recorded for each item of other information (for example, GUIDs and the like).
Various switching conditions are conceivable, and for example, the following conditions are conceivable.
However, the above switching conditions are merely examples, and various conditions can be adopted as long as being conditions for switching to another Pub in the redundant configuration.
Next, the switching possibility selection unit 710 searches for a Pub as a switching candidate using configuration information recorded in the relationship recording unit 610 and displays a search result (S105 to S106). Here, a Pub as a switching candidate can be obtained by searching for a Pub satisfying the switching condition among Pubs that distribute data of the same topic as the Pub transmitting the unauthorized data (that is, other Pubs that are made redundant). Here, it is assumed that one or more Pubs satisfying such a switching condition have been searched for.
Next, the switching possibility selection unit 710 decides a Pub as a switching destination from the one or more Pubs searched for in the above (S107). This may be decided randomly from the one or more Pubs searched for in the above, or may be decided using some criteria (for example, order decided in advance in the Pubs in the redundant configuration, and the like).
Subsequently, the switching possibility selection unit 710 transmits a command generation instruction for setting the switching destination Pub decided in the above as the priority Pub to the switching instruction output unit 720 (S108). Upon receiving the command generation instruction, the switching instruction output unit 720 generates a command for setting the switching destination Pub decided in the above S107 as the priority Pub (hereinafter, switching command), and transmits the command to the switching units 110 (S109). Note that the switching possibility selection unit 710 transmits the switching command to both the switching units 110 of the switching destination Pub and a Sub that receives data from the switching destination Pub. However, the contents of the switching command may be different between the switching destination Pub and the Sub that receives data from the switching destination Pub.
Upon receiving the switching command, the switching units 110 perform the switching command for DDS (S110). Note that, at this time, restart of the process and the like are also performed as necessary. As a result, the priority Pub is switched from the Pub transmitting the unauthorized data to the switching destination Pub.
Here, several specific methods for setting the above switching destination Pub as a priority Pub can be considered, and for example, any one of the following methods (1) to (3) can be considered.
Note that detection of generation of unauthorized data can be quickly coped with by the above method (1), but in a case where the value of OWNERSHIP_STRENGTH of a Pub transmitting the unauthorized data is set to a higher value, Subs may receive the unauthorized data again. On the other hand, while the above methods (2) and (3) are inferior to the above method (1) in quickness, there is no risk that Subs receive unauthorized data again after coping. Therefore, which of the above methods (1) to (3) is adopted may be appropriately decided in consideration of the quickness of coping and the like. Alternatively, for example, measures may be taken by the method (2) or (3) after measures are provisionally taken by the method (1).
A node including a DDS operation function unit 100 and the packet analysis device 40 including the detection unit 50, the configuration management unit 60, and the coping unit 70 in the present embodiment can be implemented, for example, by causing a computer to perform a program in which the processing contents described in the present embodiment are described.
The above program may be recorded in a computer-readable recording medium (such as a portable memory) to be stored and distributed. Also, the program may be provided through a network such as the Internet or an electronic mail.
The program for performing processes in the computer is provided through a recording medium 1001 such as a CD-ROM or a memory card, for example. When the recording medium 1001 that stores the program is set in the drive device 1000, the program is installed from the recording medium 1001 into the auxiliary storage device 1002 via the drive device 1000. However, the program is not necessarily installed from the recording medium 1001, and may be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program, and also stores necessary files, data, and the like.
In a case where an instruction to start the program is issued, the memory device 1003 reads the program from the auxiliary storage device 1002, and stores the program therein. The CPU 1004 implements functions related to the configuration management unit 60 according to the program stored in the memory device 1003. The interface device 1005 is used as an interface for connection to the network. The display device 1006 displays a graphical user interface (GUI) or the like according to the program. The input device 1007 includes a keyboard and a mouse, buttons, a touch panel, or the like, and is used to input various operation instructions. The output device 1008 outputs a calculation result. Note that the node or the packet analysis device 40 may not include either or both of the display device 1006 and the input device 1007.
According to the technology of the present embodiment, a Pub to be handled with priority on a Sub side can be switched in response to generation of unauthorized data.
The present description discloses at least a communication system, a switching apparatus, a switching method, and a program described in the following clauses.
A communication system that performs communication among a plurality of nodes by a broker-less type publishing/subscribing model, the communication system including:
The communication system according to the clause 1 further including
The communication system according to the clause 2,
A switching apparatus connected to a plurality of nodes that perform communication by a broker-less type publishing/subscribing model, the switching apparatus including:
The switching apparatus according to the clause 4 further including
The switching apparatus according to the clause 5,
A switching method performed by a switching apparatus connected to a plurality of nodes that perform communication by a broker-less type publishing/subscribing model, the switching method including:
A program causing a computer to function as the switching apparatus according to any one of clauses 4 to 6.
Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes can be made within the scope of the present invention disclosed in the claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/014230 | 4/1/2021 | WO |
