Data diode and data transfer anomaly notification method

Abstract

This enables the transmission of information from the IT network to the OT network indicating whether data transfer is normal or abnormal. [Solution] The system comprises a transmitting device 11 that transmits data from an OT-side device 2 connected to an OT network, a receiving device 13 that transmits the input data to an IT network, and a one-way communication unit 12 that transmits the data transmitted by the transmitting device 11 to the receiving device 13. The receiving device 13 has an abnormality detection unit that detects whether or not there is a data transfer abnormality, and a receiving notification unit 133 that notifies the transmitting device 11 of the presence or absence of a data transfer abnormality based on the presence or absence of a data transfer abnormality detected by the abnormality detection unit. The transmitting device 11 has a transmitting notification unit 113 that notifies the OT-side device 2 of the data transfer abnormality if there is a data transfer abnormality based on the information notified by the receiving notification unit 133.

Description

Technical Field

[0001] The present disclosure relates to a data diode that performs one-way communication and a method for notifying data transfer anomalies using the data diode.

Background Art

[0002] The OT network (control network) used in automation such as factories is used for controlling various devices and is very important. If this OT network is maliciously hijacked, abnormal control of the devices can cause accidents that are normally impossible. Thus, such an important control network generally maintains safety by not connecting to other networks.

[0003] On the other hand, it is also desired to use information generated on the OT network externally. In such cases, a data diode is effective. This data diode can only communicate in one direction and is effective as a method of physically enhancing network security (see, for example, Patent Document 1). With this data diode, data can be sent in one direction from an OT-side device connected to the OT network to an IT-side device connected to the IT network (business network). Thus, in a data diode, since communication is physically possible only in one direction, there is no network for an attacker to enter even if someone tries to hijack it maliciously. Also, in a data diode, in order to guarantee the above, it is not possible to provide any reverse information transmission path.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Thus, since data diodes enable one-way communication, the transmitting side generally cannot receive information from the receiving side. This data diode makes it possible to almost completely prevent unauthorized access.

[0006] On the other hand, data diodes cannot respond to ACK packets (received response messages) used in connection-oriented communications such as TCP / IP, nor can they respond to error information, so the sender has no choice but to always assume that the data has been sent successfully. As a result, even if a communication error occurs, the data is not retransmitted, leading to data loss. To compensate for the data loss, it was necessary to manually retrieve the missing data directly from the OT (Operational Technology) equipment.

[0007] To address this issue, there is a demand to incorporate a retransmission mechanism within the data diode to prevent data loss while ensuring security through the data diode itself.

[0008] This disclosure was made to solve the above-mentioned problems and aims to provide a data diode that can transmit information indicating whether data transfer is normal or abnormal from the business network side to the control network side. [Means for solving the problem]

[0009] The data diode according to this disclosure comprises a transmitting device that transmits data from a control-side device connected to a control network, a receiving device that transmits the input data to a business network, and a one-way communication unit that transmits the data transmitted by the transmitting device to the receiving device. The receiving device has an abnormality detection unit that detects whether or not there is a data transfer abnormality, and a receiving notification unit that notifies the transmitting device of the presence or absence of a data transfer abnormality based on the presence or absence of a data transfer abnormality detected by the abnormality detection unit. The transmitting device has a transmitting notification unit that notifies the control-side device of the data transfer abnormality if there is a data transfer abnormality based on the information notified by the receiving notification unit. [Effects of the Invention]

[0010] According to this disclosure, with the configuration described above, it becomes possible to transmit information from the business network side to the control network side indicating whether data transfer is normal or abnormal. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example configuration of a data transfer system equipped with a data diode according to Embodiment 1. [Figure 2] This is a time chart showing an example of operation of a data transfer system according to Embodiment 1, and is a time chart showing an example of normal operation. [Figure 3] This is a time chart showing an example of operation of the data transfer system according to Embodiment 1, and is a time chart showing an example of operation in the event of an abnormality (an abnormality in the third data transfer). [Figure 4] This is a time chart showing an example of operation of the data transfer system according to Embodiment 1, and is a time chart showing another example of operation in the event of an abnormality (an abnormality in the third data transfer). [Figure 5] This is a time chart showing an example of operation of the data transfer system according to Embodiment 1, and is a time chart showing an example of operation in the event of an abnormality (an abnormality in the second data transfer). [Modes for carrying out the invention]

[0012] The embodiments will be described in detail below with reference to the drawings. Embodiment 1. Figure 1 shows an example configuration of a data transfer system equipped with a data diode 1 according to Embodiment 1. In Figure 1, bidirectional arrows indicate network connections, and unidirectional thick arrows indicate the direction of data. The data transfer system includes, for example, a data diode 1, an OT-side device (control-side device) 2, and an IT-side device (operation-side device) 3, as shown in Figure 1.

[0013] The data diode 1 is a device installed between the OT network (control network) and the IT network (business network), as shown in Figure 1, for example, and enables one-way communication from the OT network to the IT network. In other words, this data diode 1 can send information from the OT network to the IT network, but it cannot send information from the IT network to the OT network.

[0014] The data diode 1 according to this embodiment 1 aims to achieve the necessary functions without creating a reverse information transmission path. Here, the necessary function is the function of notifying the OT network from the IT network side that a data transmission error has occurred when a data transmission error occurs. In other words, the objective is to realize this function, which is taken for granted in normal communication, even in the data diode 1 which cannot transmit information in the reverse direction.

[0015] An example configuration of this data diode 1 will be described later.

[0016] OT-side device 2 is connected to the OT network, as shown in Figure 1, for example. This OT-side device 2 transmits the data it wants to send to IT-side device 3 to data diode 1. Generally, the OT-side device 2 is a PC or the like, can be connected to a network such as Ethernet, and can communicate using a protocol such as TCP / IP.

[0017] As shown in FIG. 1 for example, the IT-side device 3 is connected to an IT network. This IT-side device 3 receives data from the OT-side device 2 via the data diode 1. Generally, the IT-side device 3 is a PC or the like, can be connected to a network such as Ethernet, and can communicate using a protocol such as TCP / IP.

[0018] Next, a configuration example of the data diode 1 will be described. As shown in FIG. 1 for example, this data diode 1 includes a transmission-side device 11, a one-way communication unit 12, and a reception-side device 13.

[0019] The transmission-side device 11 is connected to the OT network and transmits data from the OT-side device 2 connected to the OT network to the one-way communication unit 12. As shown in FIG. 1 for example, this transmission-side device 11 has a transmission-side data reception unit 111, a transmission-side data transmission unit 112, and a transmission-side notification unit 113.

[0020] The transmission-side data reception unit 111 receives data from the OT-side device 2 connected to the OT network.

[0021] The transmission-side data transmission unit 112 transmits the data received by the transmission-side data reception unit 111 to the one-way communication unit 12. When the reception-side data reception unit 131 described later also has the function of an abnormality detection unit, the transmission-side data transmission unit 112 adds an error detection code such as parity or CRC to the data received by the transmission-side data reception unit 111 and then transmits it to the one-way communication unit 12.

[0022] Based on the information indicating whether or not there is a data transfer abnormality notified by the receiving notification unit 133 (described later), the transmitting notification unit 113 notifies the OT-side device 2 of the data transfer abnormality via the transmitting data receiving unit 111 if there is a data transfer abnormality.

[0023] The one-way communication unit 12 transmits data from the transmitting device 11 to the receiving device 13.

[0024] The receiving device 13 is connected to the IT network and transmits data from the transmitting device 11 via the one-way communication unit 12 to the IT-side device 3, which is also connected to the IT network. As shown in Figure 1, for example, this receiving device 13 includes a receiving data receiving unit 131, a receiving data transmission unit 132, and a receiving notification unit 133.

[0025] The receiving data receiving unit 131 receives data from the transmitting device 11 via the one-way communication unit 12.

[0026] The receiving data transmission unit 132 transmits the data received by the receiving data reception unit 131 to the IT-side device 3 connected to the IT-side network.

[0027] Furthermore, at least one of the receiving data receiving unit 131 and the receiving data transmitting unit 132 also functions as an abnormality detection unit. The anomaly detection unit detects whether or not there is an anomaly in data transfer.

[0028] Here, if the receiving data receiving unit 131 also has the function of an abnormality detection unit, the receiving data receiving unit 131 detects whether or not there is a data transfer abnormality (a second data transfer abnormality described later) in the data received from the transmitting device 11 via the one-way communication unit 12. In this case, the receiving data receiving unit 131 detects whether or not an error has occurred in the data based on the error detection code attached to the received data, thereby detecting whether or not there is a data transfer abnormality. Information indicating whether or not there is a data transfer abnormality detected by the receiving data receiving unit 131 is notified to the receiving notification unit 133.

[0029] Furthermore, if the receiving data transmission unit 132 also functions as an abnormality detection unit, it detects whether there is a data transfer abnormality (the third data transfer abnormality described later) in the data transmitted to the IT-side device 3. In this case, the receiving data transmission unit 132 appropriately retransmits the data if an error occurs during data transfer, and if the data cannot be transmitted correctly even after retransmission, it detects that a data transfer abnormality has occurred. Information indicating whether or not there is a data transfer abnormality detected by the receiving data transmission unit 132 is notified to the receiving notification unit 133.

[0030] In the example shown in Figure 1, both the receiving data receiving unit 131 and the receiving data transmitting unit 132 also function as abnormality detection units.

[0031] When the receiving notification unit 133 receives information indicating whether or not there is a data transfer abnormality from at least one of the receiving data receiving unit 131 and the receiving data transmitting unit 132, it notifies the transmitting notification unit 113 of the information indicating whether or not there is a data transfer abnormality.

[0032] Here, three types of data transfer can be described as data transfer in data diode 1. The first is the data transfer from the OT-side device 2 to the transmitting device 11 via the data diode 1 (the first data transfer). Generally, protocols such as TCP / IP are used for this first data transfer. The second is data transfer (second data transfer) from the transmitting device 11 to the receiving device 13 via the one-way communication unit 12 within the data diode 1. This second data transfer is data transfer using the one-way communication unit 12, and as long as the data can be sent reliably, the protocol is not specified. The third is the data transfer from the receiving device 13 to the IT device 3 in the data diode 1 (the third data transfer). This third data transfer typically uses protocols such as TCP / IP.

[0033] Of the three data transfers mentioned above, the first data transfer is TCP / IP communication over the OT network, and since it is a connection-oriented communication, retransmission is performed as appropriate if errors occur. Furthermore, if the data cannot be transmitted correctly even after retransmission, the OT-side device 2, which is the sender, can be notified that the transmission failed. Therefore, if an abnormality occurs in the first data transfer, the OT-side device 2 can take action such as logging the information or issuing an alert. This is the same as in conventional technology.

[0034] On the other hand, of the three data transfers described above, the second data transfer is a one-way communication using the one-way communication unit 12, so if the data cannot be transferred correctly, it is basically not possible to inform the transmitting device 11, which is the source of the transmission, of the abnormality. In contrast, by adding an error detection code such as parity or CRC when sending data from the transmitting device 11 (transmitting data transmission unit 112), the receiving device 13 (receiving data receiving unit 131) can detect that an error has occurred in the data. Therefore, in the data diode 1 according to Embodiment 1, when an error is detected, the receiving data receiving unit 131 can inform the receiving notification unit 133 that an abnormality has occurred in the data transfer. The receiving notification unit 133 then informs the transmitting notification unit 113 of the abnormality in the data transfer as contact information. The transmitting notification unit 113 then informs the OT-side device 2 via the transmitting data transmission unit 112 that the data currently being transferred could not be transmitted correctly.

[0035] Furthermore, of the three data transfers mentioned above, the third data transfer is TCP / IP communication over an IT network, and since it is a connection-oriented communication, retransmission is performed as appropriate if errors occur. Furthermore, if the data cannot be transmitted correctly even after retransmission, the receiving device 13 (receiving data transmission unit 132), which is the source of the transmission, can be informed that the transmission failed. In the data diode 1 according to Embodiment 1, if the data cannot be transmitted, the receiving data transmission unit 132 can inform the receiving notification unit 133 of this fact. The receiving notification unit 133 then informs the transmitting notification unit 113 of the abnormality in data transfer as contact information. The transmitting notification unit 113 then informs the OT device 2 via the transmitting data transmission unit 112 that the data currently being transmitted could not be transmitted correctly.

[0036] Next, an example of the operation of the data transfer system according to Embodiment 1 shown in Figure 1 will be explained with reference to Figures 2 and 3. In the following, we will describe the case where the OT-side device 2 and the IT-side device 3 are PCs, and data transfer is performed using TCP / IP, a connection-type communication protocol commonly used on PCs. Furthermore, in the following, we will describe the case where the data diode 1 detects whether or not there is an abnormality in the third data transfer. Figure 2 shows an example of normal operation, while Figure 3 shows an example of abnormal operation.

[0037] In an example of the operation of the data transfer system according to Embodiment 1 shown in Figure 1, the data transfer system first performs a communication establishment process, as shown in Figures 2 and 3, for example.

[0038] In this communication establishment process, first, the OT-side device 2 sends a SYN packet to the transmitting device 11 (step ST101). Then, the transmitting device 11 sends an ACK / SYN packet to the OT device 2 in response to the SYN packet from the OT device 2 (step ST102). The transmitting device 11 also sends a CONN packet to the receiving device 13 via the one-way communication unit 12 (step ST103). Then, in response to the ACK / SYN packet from the transmitting device 11, the OT-side device 2 sends an ACK packet to the transmitting device 11 (step ST104). Furthermore, the receiving device 13 sends a SYN packet to the IT-side device 3 in response to the CONN packet from the transmitting device 11 (step ST105). Then, IT device 3 sends an ACK / SYN packet to receiving device 13 in response to the SYN packet from receiving device 13 (step ST106). Then, the receiving device 13 sends an ACK packet to the IT device 3 in response to the ACK / SYN packet from the IT device 3 (step ST107). This establishes communication between the OT-side device 2, the data diode 1, and the IT-side device 3.

[0039] Next, the data transfer system performs the data transfer process. Furthermore, the data diode 1 detects whether or not there is a data transfer anomaly. Here, the data diode 1 (receiving device 13) detects whether or not there is a data transfer anomaly (anomaly in the third data transfer) by determining whether it has received an ACK packet for the data transfer from the IT device 3 within a predetermined time from the data transfer.

[0040] In the examples in Figures 2 and 3, the data transfer system is shown transferring two data items (Data1 and Data2).

[0041] In the example shown in Figure 2, both Data1 and Data2 are successfully transferred from the receiving device 13 to the IT device 3. In this normal data transfer process, first, the OT-side device 2 sends data to the transmitting-side device 11 (steps ST108, ST113). Then, the transmitting device 11 sends an ACK packet to the OT device 2 in response to the data from the OT device 2 (steps ST109, ST114). The transmitting device 11 also sends the above data to the receiving device 13 via the one-way communication unit 12 (steps ST110, ST115). Then, the receiving device 13 transmits the data from the transmitting device 11 to the IT device 3 (steps ST111, ST116). Then, the IT device 3 sends an ACK packet to the receiving device 13 in response to the data from the receiving device 13 (steps ST112, ST117). This enables data transfer between the OT-side device 2, the data diode 1, and the IT-side device 3.

[0042] In the example shown in Figure 2, ACK packets for data transfer are sent from the IT-side device 3 to the receiving-side device 13 for both Data1 and Data2, and the data diode 1 (receiving-side device 13) detects that the data transfer of Data1 and Data2 has been successfully completed.

[0043] On the other hand, in the example shown in Figure 3, Data1 is successfully transferred from the receiving device 13 to the IT device 3, but Data2 is not successfully transferred from the receiving device 13 to the IT device 3. In this case, the IT device 3 does not receive an ACK packet from the receiving device 13 for the transfer of Data2 (the process in step ST117 is not performed).

[0044] In the example shown in Figure 3, for Data1, an ACK packet for data transfer is sent from the IT-side device 3 to the receiving device 13, and the data diode 1 (receiving device 13) detects that the data transfer of Data1 was successful. On the other hand, for Data2, no ACK packet for data transfer is received from the IT-side device 3 to the receiving device 13, and the data diode 1 (receiving device 13) detects that an abnormality occurred in the data transfer of Data2.

[0045] Next, the data transfer system performs a communication termination process. Furthermore, if the data diode 1 detects a data transfer error, it notifies the OT-side device 2 accordingly.

[0046] Here, as shown in Figure 2, under normal circumstances, the OT-side device 2 first sends a FIN packet to the transmitting device 11 (step ST118). Then, in response to the FIN packet from the OT-side device 2, the transmitting device 11 sends a DISC packet to the receiving device 13 via the one-way communication unit 12 (step ST119). Then, in the example in Figure 2, the receiving device 13 receives an ACK packet for data transfer from the IT device 3, and therefore sends a FIN packet to the IT device 3 in response to the DISC packet from the transmitting device 11 (step ST120). Then, IT device 3 sends an ACK / FIN packet to receiving device 13 in response to the FIN packet from receiving device 13 (step ST121). Then, the receiving device 13 sends an ACK packet to the IT-side device 3 in response to the ACK / FIN packet from the IT-side device 3 (step ST122). The receiving device 13 also notifies the transmitting device 11 of normal contact information (OK information) indicating that there is no abnormality in data transfer (step ST123). Then, the transmitting device 11 sends an ACK / FIN packet to the OT device 2 in response to the normal contact information (OK information) from the receiving device 13 (step ST124). Then, in response to the ACK / FIN packet from the transmitting device 11, the OT-side device 2 sends an ACK packet to the transmitting device 11 (step ST125). This terminates communication between the OT-side device 2, data diode 1, and IT-side device 3.

[0047] On the other hand, as shown in Figure 3, in the event of an abnormality, the OT-side device 2 first sends a FIN packet to the transmitting device 11 (step ST118). Then, in response to the FIN packet from the OT-side device 2, the transmitting device 11 sends a DISC packet to the receiving device 13 via the one-way communication unit 12 (step ST119). In the example shown in Figure 3, the receiving device 13 has not received an ACK packet for the data transfer from the IT-side device 3 within a predetermined time from the data transfer, so in response to the DISC packet from the transmitting device 11, it sends an RST packet to the IT-side device 3 (step ST201). The receiving device 13 also notifies the transmitting device 11 of abnormal contact information (NG information) indicating that there is an abnormality in the data transfer (step ST202). Then, the IT device 3 disconnects the communication in response to the RST packet from the receiving device 13. Furthermore, the transmitting device 11 sends an RST packet to the OT device 2 in response to abnormal contact information (NG information) from the receiving device 13 (step ST203). Then, OT-side device 2 disconnects the communication in response to the RST packet from transmitting device 11. This forcibly terminates communication between the OT-side device 2, data diode 1, and IT-side device 3.

[0048] Thus, as shown in Figure 2, for example, if no irrecoverable error occurs during communication in the connection, the transmitting device 11 receives normal contact information (OK information) from the receiving device 13 and then sends a packet with the FIN flag set (FIN packet) to the source OT device 2 to terminate the connection. This allows the data transfer system to indicate that data transfer via this connection has been successfully completed.

[0049] On the other hand, as shown in Figure 3, for example, if an unrecoverable error occurs during communication within a single connection, the receiving device 13 transmits abnormal contact information (NG information) to the transmitting device 11, and the transmitting device 11 sends a packet with the RST flag set (RST packet) to the source OT device 2. This allows the data transfer system to trigger a forced disconnection and indicate that data transfer via this connection has failed. As a result, the OT device 2 can quickly retransmit the data.

[0050] Note that while the above describes a forced disconnection using an RST packet in TCP / IP when an anomaly occurs, other methods of disconnection may also be used. For example, Figure 4 shows a case where a disconnection is performed using a FIN packet when an anomaly occurs. This method takes advantage of the fact that arbitrary information can be transmitted to OT device 2 and IT device 3 because the connection between OT device 2 and IT device 3 is TCP / IP.

[0051] In this case, first, the OT-side device 2 sends a FIN packet to the transmitting device 11 (step ST118). Then, in response to the FIN packet from the OT-side device 2, the transmitting device 11 sends a DISC packet to the receiving device 13 via the one-way communication unit 12 (step ST119). In the example shown in Figure 4, the receiving device 13 has not received an ACK packet for data transfer from the IT-side device 3 within a predetermined time from the data transfer. Therefore, in response to the DISC packet from the transmitting device 11, it sends a FIN packet to the IT-side device 3 with abnormality notification data (Data3 in Figure 4) attached (step ST301). The abnormality notification data is message data to convey an abnormality and is data that has been agreed upon in advance between the OT-side device 2 and the IT-side device 3 as a "message when an abnormality occurs". The receiving device 13 also notifies the transmitting device 11 of abnormal contact information (NG information) indicating that there is an abnormality in the data transfer (step ST302). Then, IT device 3 sends an ACK / FIN packet to receiving device 13 in response to the FIN packet from receiving device 13 that has abnormality notification data attached to it (step ST303). Then, the receiving device 13 sends an ACK packet to the IT device 3 in response to the ACK / FIN packet from the IT device 3 (step ST304). Furthermore, the transmitting device 11 sends an ACK / FIN packet with abnormal contact information (NG information) attached to it to the OT device 2 in response to abnormal contact information (NG information) from the receiving device 13 (step ST305). Then, the OT-side device 2 sends an ACK packet to the transmitting device 11 in response to the ACK / FIN packet from the transmitting device 11 which has abnormality notification data attached to it (step ST306). This terminates communication between the OT-side device 2, data diode 1, and IT-side device 3.

[0052] Furthermore, the above describes the case where data diode 1 detects whether or not there is an abnormality in the third data transfer. In contrast, the case where data diode 1 detects whether or not there is an abnormality in the second data transfer, and an example of operation in the event of an abnormality, is shown, for example, in Figure 5.

[0053] In this case, for example, as shown in Figure 5, the data transfer system first performs a communication establishment process. This communication establishment process is the same as the communication establishment process shown in Figures 2 to 4, and its explanation will be omitted.

[0054] Next, the data transfer system performs data transfer processing. This data transfer processing is the same as the data transfer processing shown in Figures 2 to 4, and therefore its explanation is omitted. Furthermore, the data diode 1 detects whether or not there is a data transfer anomaly. Here, the data diode 1 (receiving device 13) detects whether or not there is a data transfer anomaly (second data transfer anomaly) based on the error detection code contained in the data from the transmitting device 11.

[0055] In the example shown in Figure 5, the data transfer system transfers two data items (Data1 and Data2).

[0056] In the example in Figure 5, Data1 is transferred successfully, but Data2 is not transferred successfully from the transmitting device 11 to the receiving device 13.

[0057] In the example shown in Figure 5, for Data1, data diode 1 detects that the data transfer was successful. On the other hand, for Data2, data diode 1 detects that an abnormality occurred in the data transfer.

[0058] Next, the data transfer system performs a communication termination process. Furthermore, if the data diode 1 detects a data transfer error, it notifies the OT-side device 2 accordingly.

[0059] Here, as shown in Figure 5, in the event of an abnormality, the OT-side device 2 first sends a FIN packet to the transmitting device 11 (step ST118). Then, in response to the FIN packet from the OT-side device 2, the transmitting device 11 sends a DISC packet to the receiving device 13 via the one-way communication unit 12 (step ST119). In the example shown in Figure 5, the receiving device 13 is unable to transfer data to the IT-side device 3, so in response to the DISC packet from the transmitting device 11, it sends an RST packet to the IT-side device 3 (step ST401). The receiving device 13 also notifies the transmitting device 11 of abnormal contact information (NG information) indicating that there is an abnormality in data transfer (step ST402). Then, the IT device 3 disconnects the communication in response to the RST packet from the receiving device 13. Furthermore, the transmitting device 11 sends an RST packet to the OT device 2 in response to abnormal contact information (NG information) from the receiving device 13 (step ST403). Then, OT-side device 2 disconnects the communication in response to the RST packet from transmitting device 11. This forcibly terminates communication between the OT-side device 2, data diode 1, and IT-side device 3.

[0060] As described above, the data diode 1 according to Embodiment 1 provides contact information from the IT side to the OT side within the data diode 1, enabling the transmission of data transfer status. The contact information is for transmitting the results of the determination of whether data transfer is normal or abnormal based on the communication performed by the IT side to the OT side, and cannot transmit any other information. Furthermore, the contact information is generated internally on the IT side of the data diode 1 and cannot be controlled by communication from the IT side. Furthermore, in the data diode 1 according to Embodiment 1, if the IT side informs the OT side that the data transfer is normal, the OT side terminates normally. On the other hand, if the IT side informs the OT side that the data transfer is abnormal, the OT side can retransmit the data. Based on the above, the data diode 1 according to Embodiment 1 ensures security through one-way communication of the data diode 1 while enabling retransmission in the event of an abnormality.

[0061] As described above, according to this embodiment 1, the data diode 1 comprises a transmitting device 11 that transmits data from an OT-side device 2 connected to an OT network, a receiving device 13 that transmits the input data to an IT network, and a one-way communication unit 12 that transmits the data transmitted by the transmitting device 11 to the receiving device 13. The receiving device 13 has an abnormality detection unit that detects whether or not there is a data transfer abnormality, and a receiving notification unit 133 that notifies the transmitting device 11 of the presence or absence of a data transfer abnormality based on the presence or absence of a data transfer abnormality detected by the abnormality detection unit. The transmitting device 11 has a transmitting notification unit 113 that notifies the OT-side device 2 of the data transfer abnormality if there is a data transfer abnormality based on the information notified by the receiving notification unit 133. As a result, the data diode 1 according to Embodiment 1 can transmit information from the IT network side to the OT network side indicating whether the data transfer is normal or abnormal. Consequently, the data diode 1 according to Embodiment 1 can retransmit data to compensate for data loss without creating a reverse information transmission path.

[0062] Furthermore, according to this embodiment 1, the receiving device 13 has a receiving data receiving unit 131 that receives data transmitted by the transmitting device 11 via a one-way communication unit 12, and the receiving data receiving unit 131 also has the function of an abnormality detection unit that detects whether or not there is a transmission abnormality in the received data. Furthermore, according to this embodiment 1, the transmitting device 11 has a transmitting data transmission unit 112 that transmits data from the control device after adding an error detection code, and the receiving data receiving unit 131 detects whether or not there is a data transfer error based on the error detection code added to the received data. As a result, the data diode 1 according to Embodiment 1 can transmit information indicating whether the data transfer (second data transfer) from the transmitting device 11 to the receiving device 13 within the data diode 1 is normal or abnormal.

[0063] Furthermore, according to this embodiment 1, the receiving device 13 has a receiving data transmission unit 132 that transmits the input data to the IT network, and the receiving data transmission unit 132 also has the function of an abnormality detection unit that detects whether or not there is an abnormality in the transmission of the transmitted data. As a result, the data diode 1 according to Embodiment 1 can transmit information indicating whether the data transfer (third data transfer) from the receiving device 13 to the IT device 3 in the data diode 1 is normal or abnormal.

[0064] Furthermore, according to this embodiment 1, the data transfer anomaly notification method is a data transfer anomaly notification method in a data diode 1 comprising a transmitting device 11 that transmits data from an OT-side device 2 connected to an OT network, a receiving device 13 that transmits the input data to an IT network, and a one-way communication unit 12 that transmits the data transmitted by the transmitting device 11 to the receiving device 13. The receiving device 13 has an anomaly detection unit that detects whether or not there is a data transfer anomaly, and a receiving notification unit 133 that notifies the transmitting device 11 of the presence or absence of a data transfer anomaly based on the presence or absence of a data transfer anomaly detected by the anomaly detection unit. The transmitting device 11 has a transmitting notification unit 113 that notifies the OT-side device 2 of the data transfer anomaly if there is a data transfer anomaly based on the information notified by the receiving notification unit 133. As a result, the data transfer anomaly notification method according to Embodiment 1 enables the transmission of information from the IT network side to the OT network side indicating whether the data transfer is normal or abnormal. Consequently, the data transfer anomaly notification method according to Embodiment 1 enables retransmission to compensate for data loss without creating a reverse information transmission path.

[0065] Furthermore, any component of the embodiment can be modified, or any component of the embodiment can be omitted. [Explanation of Symbols]

[0066] 1 Data Diode 2 OT-side equipment (control-side equipment) 3 IT side equipment (business side equipment) 11. Transmitter equipment 12 One-way communication unit 13 Receiving device 111 Transmitter-side data receiver 112 Transmitter-side data transmission unit 113 Sender Notification Unit 131 Receiving side data receiving unit 132 Receiving side data transmission unit 133 Receiving side notification unit

Claims

1. A transmitting device that transmits data from control devices connected to a control network, A receiving device that transmits the input data to the business network, The system includes a one-way communication unit that transmits data transmitted by the transmitting device to the receiving device, The receiving device is, An anomaly detection unit that detects whether or not there is an anomaly in data transfer, The system includes a receiving notification unit that notifies the transmitting device of information indicating whether or not there is a data transfer abnormality based on the presence or absence of a data transfer abnormality detected by the abnormality detection unit, The transmitting device is, Based on information indicating whether or not there is a data transfer abnormality notified by the receiving notification unit, the transmitting notification unit notifies the control unit of the data transfer abnormality if there is a data transfer abnormality. A data diode characterized by the following features.

2. The receiving device is, The receiving side has a data receiving unit that receives data transmitted by the transmitting device via the one-way communication unit, The receiving data receiving unit also has the function of the abnormality detection unit, and detects whether or not there is a transmission abnormality in the received data. The data diode according to feature 1.

3. The transmitting device is, The system includes a transmitting data transmission unit that transmits data from the control device after adding an error detection code. The receiving data receiving unit detects whether or not there is a data transfer error based on the error detection code attached to the received data. The data diode according to feature 2.

4. The receiving device is, It has a receiving data transmission unit that transmits the input data to the business network, The receiving data transmission unit also has the function of the abnormality detection unit and detects whether or not there is a transfer abnormality in the transmitted data. A data diode according to claim 1 or 2, characterized by the above.

5. A transmitting device that transmits data from control-side devices connected to a control network, A receiving device that transmits the input data to the business network, A data transfer abnormality notification method in a data diode comprising a one-way communication unit that transmits data transmitted by the transmitting device to the receiving device, The receiving device is, The abnormality detection unit detects whether or not there is an abnormality in data transfer. The receiving notification unit notifies the transmitting device of information indicating whether or not there is a data transfer abnormality, based on whether or not there is a data transfer abnormality detected by the abnormality detection unit. The transmitting device is, The transmitting notification unit notifies the control device of the data transfer abnormality if one occurs, based on the information indicating whether or not there is a data transfer abnormality notified by the receiving notification unit. A method for notifying data transfer abnormalities, characterized by the following features.

Images