JP7270668B2 - Routing control device, routing control method and routing control program - Google Patents

Description

The present disclosure relates to techniques for increasing the availability of network systems with security devices connected inline.

Introduction of IoT (Internet of Things) technology is spreading in production lines of factories in the manufacturing industry and the like. Along with this, the importance of implementing security measures in production lines is increasing. However, implementation of security measures has been delayed due to the difficulty of changing the configuration of the network system that constitutes the production line and the lack of knowledge of the network system on site.

As a security measure that is relatively easy to introduce, there is a measure in which security devices that monitor communication data are installed at various locations in an OT (Operational Technology) network by in-line connection. Japanese Patent Laid-Open No. 2004-100000 describes connecting a security device by an in-line connection. Connecting a security device in-line means connecting the security device in series between devices such as network devices.

Japanese Patent Application Laid-Open No. 2008-028740

If the security device is connected in-line, communication between the devices will not be possible if the security device breaks down, thus reducing the availability of the network system.
The present disclosure aims at increasing the availability of network systems with security devices connected in-line.

The route control device according to the present disclosure is
A route control device that enables bypassing of a security device connected inline between a first device and a second device,
a determination unit that determines whether the security device is normal based on a signal acquired from the security device;
When the determination unit determines that the security device is normal, communication data from one of the first device and the second device to the other is transmitted via the security device, and the determination unit a route switching unit configured to switch a route so that communication data from the one to the other is transmitted by bypassing the security device when it is determined that the security device is not normal.

In the present disclosure, when the security device is normal, the communication data is transmitted via the security device, and when the security device is not normal, the route is switched so that the communication data is transmitted bypassing the security device. be done. This allows communication between the first device and the second device even if the security device fails. Therefore, the availability of a network system with security devices connected inline can be increased.

1 is a configuration diagram of a network system 100 according to Embodiment 1; FIG. 1 is a configuration diagram of a route control device 10 according to Embodiment 1; FIG. 4 is an explanatory diagram of setting data 31 according to the first embodiment; FIG. 4 is an explanatory diagram of reference signal data 32 according to the first embodiment; FIG. 4 is a flowchart of an outline of processing of the route control device 10 according to Embodiment 1; 6 is an explanatory diagram of data acquisition processing (step S1 in FIG. 5) according to the first embodiment; FIG. 4 is a flow chart of determination processing (step S2) and route switching processing (step S3) according to the first embodiment; FIG. 2 is an explanatory diagram of a normal route according to the first embodiment; FIG. 4 is an explanatory diagram of a bypass route according to the first embodiment; FIG. FIG. 4 is an explanatory diagram of data conversion when using 100BASE-TX according to the first embodiment; FIG. 4 is an explanatory diagram of a method of calculating reference signal data 32 from a signal train according to the first embodiment; FIG. 4 is an explanatory diagram of a method of calculating a correlation coefficient C between a partial signal sequence and reference signal data 32 according to Embodiment 1; FIG. 4 is an explanatory diagram of a method of calculating a correlation coefficient C between a partial signal sequence and reference signal data 32 according to Embodiment 1; FIG. 4 is an explanatory diagram of a method of calculating a correlation coefficient C between a partial signal sequence and reference signal data 32 according to Embodiment 1; FIG. 2 is a configuration diagram of a route control device 10 according to Modification 1; FIG. 10 is a configuration diagram of a route control device 10 according to Modification 2;

Embodiment 1.
*** Configuration description ***
A configuration of a network system 100 according to the first embodiment will be described with reference to FIG.
A network system 100 includes a route control device 10 , a first device 51 , a second device 52 and a security device 53 . The route control device 10 is connected to the first device 51 , the second device 52 , the security device 53 and the transmission line 60 . In other words, the security device 53 is in-line connected between the first device 51 and the second device 52 via the route control device 10 .

The routing control device 10 is a computer that enables bypassing of a security device connected inline between the first device and the second device. The first device 51 and the second device 52 are network devices such as hubs and switches. Also, the first device 51 and the second device 52 may be computers such as PCs (Personal Computers) or IoT devices such as sensors instead of network devices. The security device 53 is a computer that monitors communication data between the first device and the second device and detects unauthorized communication data.

The configuration of the route control device 10 according to the first embodiment will be described with reference to FIG.
The routing control device 10 is a computer.
The path control device 10 includes hardware including a processor 11, a storage device 12, input/output interfaces 13A and 13B, distributors 14A and 14B, A/D converters 15A and 15B, and switches 16A and 16B. . The processor 11 is connected to other hardware via signal lines and controls these other hardware.

The processor 11 is an IC (Integrated Circuit) that performs processing. Specific examples of the processor 11 are a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit).

The storage device 12 is a storage device that stores data. Specific examples of the storage device 12 include RAM (Random Access Memory), HDD (Hard Disk
Drive). The storage device 12 can be an SD (registered trademark, Secure Digital) memory card, a CF (Compact Flash, a registered trademark), a NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD (Digital Versatile Disk). It may be a carrier recording medium.

The input/output interfaces 13A and 13B are interfaces for communicating with external devices. The input/output interfaces 13A and 13B are, for example, Ethernet (registered trademark) and USB (Universal Serial Bus) ports.

The distributors 14A and 14B are devices for duplicating and outputting input data. The distributors 14A and 14B output the data input from the input/output interfaces 13A and 13B to the changeover switches 16A and 16B, and duplicate the data input from the input/output interfaces 13A and 13B to convert them to A/D converters 15A and 15B. 15B.

The A/D converters 15A and 15B are devices that convert analog signals into digital signals. A/D converters 15A and 15B convert the analog data output from distributors 14A and 14B into digital data and output the digital data to processor 11 .

The changeover switches 16A and 16B are devices that switch paths under the control of the processor 11 . The selector switches 16A and 16B are connected to the selector switch 16A and the distributor 14A, and have a normal path to which the selector switch 16B and the distributor 14B are connected, and a bypass to which the selector switch 16A and the selector switch 16B are connected. Switch between routes.

The route control device 10 includes a data acquisition unit 21, a determination unit 22, and a route switching unit 23 as functional components. The function of each functional component of the route control device 10 is realized by software.
The storage device 12 stores a program that implements the function of each functional component of the routing control device 10 . This program is read by the processor 11 and executed by the processor 11 . Thereby, the function of each functional component of the route control device 10 is realized.

The storage device 12 stores setting data 31 and reference signal data 32 .

Only one processor 11 was shown in FIG. However, there may be a plurality of processors 11, and the plurality of processors 11 may cooperate to execute programs that implement each function.

***Description of operation***
The operation of the route control device 10 according to the first embodiment will be described with reference to FIGS. 3 to 11. FIG.
The operation procedure of the routing control device 10 according to the first embodiment corresponds to the routing control method according to the first embodiment. Also, a program that realizes the operation of the routing control device 10 according to the first embodiment corresponds to the routing control program according to the first embodiment.

The setting data 31 according to the first embodiment will be described with reference to FIG.
The setting data 31 includes setting values for two settings, ie, the threshold value of the correlation coefficient and the interval until failure determination. In FIG. 3, a value th is set as a set value for the threshold value of the correlation coefficient. In FIG. 3, the reference time x is set as the set value for the interval until failure determination.

Reference signal data 32 according to the first embodiment will be described with reference to FIG.
A calculated value is set for each time in the reference signal data 32 . ₄ , calculated values _{M 1 ,} . . . _Mn is set.

Here, it is assumed that the security device 53 transmits a reference signal train, which is a signal train having a fixed form, at least once within a certain period of time. This fixed period or a time slightly longer than the fixed period becomes the reference time x, which is the interval until failure determination. The reference signal train may be any signal train, but is a signal train that is periodically transmitted, for example, an ARP (Address Resolution Protocol) request. Reference signal data 32 are calculated from the reference signal sequence. The reference signal string is specified by the administrator of the network system 100 or determined according to the model of the security device 53 or the like.
A method of calculating the reference signal data 32 from the reference signal train will be described later.

With reference to FIG. 5, an outline of processing of the route control device 10 according to the first embodiment will be described.
As a premise for the processing in FIG. 5, it is assumed that signals are sequentially transmitted from the security device 53 . A signal transmitted from the security device 53 to the first device 51 is output from the input/output interface 13A to the distributor 14A, duplicated by the distributor 14A, and converted from analog data to digital data by the A/D converter 15A. and output to the processor 11. A signal transmitted from the security device 53 to the second device 52 is output from the input/output interface 13B to the distributor 14B, duplicated by the distributor 14B, and converted from analog data to digital data by the A/D converter 15B. and output to the processor 11.

(Step S1: Data Acquisition Processing)
The data acquisition unit 21 acquires a transmission signal sequence, which is digital data output to the processor 11 . The data acquisition unit 21 cuts out a partial signal sequence that constitutes the transmission signal sequence. The data acquisition unit 21 cuts out a partial signal sequence composed of the same n signal values as the reference signal data 32 . For example, as shown in FIG. 6, the data acquisition unit 21 cuts out a string of n signal values as a partial signal string while shifting the signal values one by one. Then, the data acquisition unit 21 sequentially supplies the extracted partial signal sequences to the determination unit 22 .

(Step S2: judgment processing)
The determination unit 22 determines whether or not the security device 53 is normal based on the transmission signal sequence acquired from the security device 53 .
Specifically, the determination unit 22 determines that the security device 53 is normal when the reference signal sequence is included in the partial signal sequence extracted from the transmission signal sequence transmitted from the security device 53 at the reference time. do. On the other hand, the determination unit 22 determines that the security device 53 is not normal when the reference signal sequence is not included in the partial signal sequence extracted from the transmission signal sequence transmitted from the security device 53 at the reference time.

(Step S3: Path switching process)
When the security device 53 is determined to be normal, the route switching unit 23 transmits communication data from one of the first device 51 and the second device 52 to the other via the security device 53, and the security device 53 is not normal, the route is switched so that communication data from one of the first device 51 and the second device 52 to the other is transmitted bypassing the security device 53 .

The determination process (step S2) and route switching process (step S3) according to the first embodiment will be described with reference to FIG.
The processing of steps S101 to S104, the processing of steps S106 to S108, and the processing of step S110 correspond to the determination processing. The processing of step S105 and the processing of step S109 correspond to route switching processing.

(Step S101: reset processing)
The determination unit 22 resets the timer to 0.

(Step S102: Correlation calculation process)
The determination unit 22 acquires an unprocessed partial signal sequence. The determination unit 22 then calculates a correlation coefficient C between the acquired partial signal sequence and the reference signal data 32 . A method of calculating the correlation coefficient C between the partial signal sequence and the reference signal data 32 will be described later.

(Step S103: threshold determination processing)
The determination unit 22 determines whether or not the correlation coefficient C calculated in step S102 exceeds the correlation coefficient threshold th indicated by the setting data 31 .
If the correlation coefficient C exceeds the threshold th, the determination unit 22 advances the process to step S104. On the other hand, if the correlation coefficient C does not exceed the threshold th, the determination unit 22 advances the process to step S107.

(Step S104: First state determination processing)
The determination unit 22 determines whether the state of the currently managed security device 53 is normal.
If the state is normal, the determination unit 22 returns the process to step S101. On the other hand, if the state is not normal (here, referred to as a failure state), the determination unit 22 advances the process to step S105.

(Step S105: First route switching process)
The path switching unit 23 switches the path to the normal path by transmitting a normal switching signal to the switch 16A and the switch 16B.
As shown in FIG. 8, the normal route is that communication data from the first device 51 to the second device 52 and communication data from the second device 52 to the first device 51 are transmitted via the security device 53. It is a route that Specifically, the switch 16A opens the port on the side of the distributor 14A and closes the port on the side of the switch 16B. The changeover switch 16B opens the port on the side of the distributor 14B and closes the port on the side of the changeover switch 16A.
Thereby, the communication data transmitted from the first device 51 is transmitted from the switch 16A to the security device 53 via the distributor 14A and the input/output interface 13A. Then, it is transmitted from the security device 53 to the second device 52 from the switch 16B via the input/output interface 13B and the distributor 14B. The communication data transmitted from the second device 52 is transmitted from the selector switch 16B to the security device 53 via the distributor 14B and the input/output interface 13B. Then, it is transmitted from the security device 53 to the first device 51 from the switch 16A via the input/output interface 13A and the distributor 14A.

(Step S106: First state switching process)
The path switching unit 23 switches the state of the security device 53 from the failure state to the normal state.

(Step S107: second state determination processing)
The determination unit 22 determines whether the state of the currently managed security device 53 is normal.
If the state is normal, determination unit 22 advances the process to step S108. On the other hand, if the state is the failure state, the determination unit 22 returns the process to step S102.

(Step S108: timer determination processing)
The determination unit 22 determines whether or not the time indicated by the timer exceeds the reference time x, which is the interval until failure determination indicated by the setting data 31 .
If the time indicated by the timer exceeds the reference time x, the determination unit 22 advances the process to step S109. On the other hand, if the time indicated by the timer does not exceed the reference time x, the determination unit 22 returns the process to step S102.

(Step S109: second route switching process)
The route switching unit 23 transmits a failure switching signal to the changeover switches 16A and 16B to switch the route to the bypass route.
As shown in FIG. 9 , the bypass path allows communication data from the first device 51 to the second device 52 and communication data from the second device 52 to the first device 51 to bypass the security device 53 . This is the route sent by Specifically, the changeover switch 16A closes the port on the side of the distributor 14A and opens the port on the side of the changeover switch 16B. Further, the changeover switch 16B closes the port on the side of the distributor 14B and opens the port on the side of the changeover switch 16A.
As a result, the communication data transmitted from the first device 51 is transmitted from the changeover switch 16A to the changeover switch 16B and then transmitted from the changeover switch 16B to the second device 52 . The communication data transmitted from the second device 52 is transmitted from the changeover switch 16B to the changeover switch 16A and transmitted from the changeover switch 16A to the first device 51 .

(Step S110: second state switching process)
The path switching unit 23 switches the state of the security device 53 from the normal state to the failure state.

A method of calculating the reference signal data 32 from the reference signal sequence will be described with reference to FIGS. 10 and 11. FIG.
In FIG. 10, the case of using 100BASE-TX is shown as an example. In 100BASE-TX, any MAC (Media Access Control) frame is 4B/5B encoded, then scrambled, then parallel/serial converted, then NRZI (Non Return to Zero Inversion) encoding is performed, and then MLT-3 (Multi Level Transmission-3) encoding is performed. Waveform transformation is then performed, and conversion to an electrical waveform is performed and transmitted. Of these, from 4B/5B encoding to MLT-3 encoding enclosed in a frame in FIG. . Therefore, if the data sequence of the MAC frame is known, it is possible to calculate up to the output value of MLT-3 encoding, which is the output value immediately before waveform conversion.
Although 100BASE-TX is shown as an example in FIG. 10, output values immediately before waveform conversion can be calculated from an arbitrary data string even for other standards.

Here, the numerical value sequence, which is the output value immediately before the waveform conversion, is assumed to be the signal sequence A(m). m is a positive integer. Also, as shown in FIG. 11, let _Tb be the time interval for one value when converting a signal sequence into an electrical signal, and let _fs be the sampling frequency of the path control device 10 . Here, from the sampling theorem, f _s >2/T _b .
As shown in FIG. 11, the time i/ _fs at which the i-th sampling is performed is after the c-th time _Tb ·c in the signal sequence A(m) and before the c+1-th time _Tb ·c+1. Suppose there is In this case, the calculated value M _i of the reference signal data 32 becomes the signal series A(c). That is, M _i =A(c). However, M ₀ =A(0) and T _b ·c≦i/f _s <T _b ·(c+1).

Therefore, by determining the signal train from which the reference signal data 32 is generated, like the ARP request, the signal _train A(m) can be calculated. based on f _s , i=1, . . . , n, the calculated value M _i of the reference signal data 32 can be calculated.

The transmission signal train used in step S1 of FIG. 5 is a signal train generated by sampling the output waveform output from the security device 53 at every sampling interval of 1/ _fs . If the output signal train from the A/D converter 15A or A/D converter 15B is a signal train sampled at sampling intervals of 1/ _fs , the output signal train becomes the transmission signal train as it is. If the signal train output from the A/D converter 15A or the A/D converter 15B is not a signal train sampled at every sampling interval of 1/ _fs , the data acquisition unit 21 outputs the output signal train at the sampling interval of 1/fs. It is converted into a signal train sampled every _fs and used as a transmission signal train.

A method of calculating the correlation coefficient C between the partial signal sequence and the reference signal data 32 will be described with reference to FIGS. 12 to 14. FIG.
For a given sequence x, y, the correlation coefficient Corr can be calculated by equation (1).

Assume that a partial signal sequence is obtained as shown in FIG. At this time, the memory on the time axis becomes each sampling point i, and the value of the partial signal sequence at each sampling point i is represented as Sample(i). Here, i has a value of 0 at the starting point of the time axis and increases by 1 for each memory. In addition, in FIG. 12, the partial signal train is represented as a clean waveform, but in reality, it is affected by noise and the like, and does not become a clean waveform.

As shown in FIG. 13, the determination unit 22 sets the element x ₀ in the sequence x as x ₀ =Sample(0). Here, since the sampling interval is 1/f _s , the number m of sampling points separated by the time interval T _b when the original signal sequence is converted into an electrical signal is m=T _b f _s . . Here, numbers below the decimal point are truncated. The determination unit 22 uses this number m to determine i=1, . . . , n, define an element x _i in the sequence x for each integer i as x _i =Sample(0+im).
The determination unit 22 causes the values of the reference signal data 32 to correspond to the sequence y as they are. That is, the determination unit 22 determines y ₀ =M(0), y ₁ =M(1), . . . , y _n =M(n). Then, the correlation coefficient Corr of the series x and y is calculated by Equation 1 and set as the correlation coefficient Corr(0).

As shown in FIG. 14, the determination unit 22 sets the element x ₀ in the sequence x as x ₀ =Sample(1). The determination unit 22 determines i=1, . . . , n for each integer i, define an element x _i in the sequence x as x _i =Sample(1+im). The sequence y is the same as when calculating the correlation coefficient Corr(0). Then, the correlation coefficient Corr of the series x and y is calculated by Equation 1 and set as the correlation coefficient Corr(1).

Similarly, the determination unit 22 sets the element x ₀ in the sequence x as x ₀ =Sample(L) and defines the element x _i as _xi =Sample(L+im) in the range of L≦m. Then, the processing for calculating the correlation coefficient Corr(L) is repeated. Then, the determination unit 22 determines L=0, 1, . . . Let the maximum value Max(Corr) be the correlation coefficient C among the correlation coefficients Corr(L).

*** Effect of Embodiment 1 ***
As described above, in the route control device 10 according to the first embodiment, when the security device 53 is determined to be normal, the communication data from the first device 51 to the second device 52 is transmitted through the security device 53. When it is determined that the security device 53 is not normal, the route is switched so that the communication data from the first device 51 to the second device 52 bypasses the security device 53 and is transmitted.
Thereby, even if the security device 53 fails, the communication between the first device 51 and the second device 52 can be continued. Therefore, it is possible to increase the availability of the network system 100 with the security device 53 connected inline.

Further, the route control device 10 according to the first embodiment is configured to physically switch routes. Therefore, it is possible to configure so that communication between the first device 51 and the second device 52 is not disconnected even if the power of the route control device 10 is not turned on. Therefore, it is possible to suppress deterioration in availability due to the introduction of the route control device 10 .
Supplementary explanation will be made regarding the configuration so that communication between the first device 51 and the second device 52 is not cut off when the power of the route control device 10 is not turned on. As shown in FIG. 2, the path in the path control device 10 connecting the first device 51 to the security device 53 includes devices such as an input/output interface 13A, a distributor 14A, and a selector switch 16A. These devices can be configured to pass communication data even if the power of the routing control device 10 is off. That is, it is possible to configure as if the input/output interface 13A to the changeover switch 16A are connected by a cable. The same applies to the route in the route control device 10 connecting the second device 52 to the security device 53 . Therefore, it is possible to configure so that communication between the first device 51 and the second device 52 is not disconnected even if the power of the route control device 10 is not turned on.

Further, the route control device 10 according to Embodiment 1 determines whether or not the security device 53 is normal based on the electrical waveform of the transmission signal train. Therefore, it is not necessary for the route control device 10 to perform processing related to communication frames used by the security device 53 and processing related to the communication protocol employed by the security device 53 . Therefore, the route control device 10 does not need to implement processing corresponding to the security device 53, and the route control device 10 can be easily introduced.

Further, the route control device 10 according to Embodiment 1 determines whether or not the security device 53 is normal by calculating the correlation coefficient between the transmission signal sequence and the reference signal data 32 .
The method of calculating the correlation coefficient is less prone to erroneous determination than the method of detecting the voltage level of the transmission signal string. In the case of the method of detecting the voltage level of the transmission signal train, the voltage used as the judgment reference may be generated by an unexpected signal, so there is a possibility that an erroneous judgment may occur. However, if a correlation coefficient between signals of a certain length is calculated, it is possible to make erroneous determination less likely to occur.
Further, if the method is to calculate the correlation coefficient, it is also possible to extend the method by changing the signal train from which the reference signal data 32 is generated.

It should be noted that the route control device 10 according to the first embodiment appropriately detects a failure of the security device 53 when the security device 53 cannot output an electrical signal due to a hardware abnormality such as a power supply or circuit failure. can do. However, in the routing control device 10 according to the first embodiment, the security device 53 behaves differently from normal due to a software bug or the like, but the signal train from which the reference signal data 32 is generated is not output. If it is, it cannot be detected as a failure of the security device 53 .

Further, the route control device 10 according to the first embodiment also detects a state in which the electrical signal from the security device 53 is physically cut off and communication is interrupted as failure of the security device 53 . Similarly, the path control device 10 according to the first embodiment does not deal with abnormal behavior of the security device 53, but with respect to a state in which the communication path with the security device 53 is physically cut off and the signal stops. is also detected as a failure of the security device 53 .

***Other Configurations***
<Modification 1>
When the security device 53 is determined to be abnormal, the route control device 10 may notify a specified terminal such as the terminal of the administrator of the network system 100 that the security device 53 is determined to be abnormal.
In this case, as shown in FIG. 15, the route control device 10 has a notification unit 24 as a functional component. The notification unit 24 notifies the specified terminal that the security device 53 is determined not to be normal when the normal state is switched to the failure state in step S110 of FIG.

<Modification 2>
In Embodiment 1, each functional component is realized by software. However, as Modification 2, each functional component may be implemented by hardware. Regarding this modification 2, the points different from the first embodiment will be described.

The configuration of the route control device 10 according to Modification 2 will be described with reference to FIG.
When each functional component is implemented by hardware, the route control device 10 has an electronic circuit 17 instead of the processor 11 . The electronic circuit 17 is a dedicated circuit that implements the function of each functional component.

The electronic circuit 17 includes a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programmable Gate Array). is assumed.
Each functional component may be implemented by one electronic circuit 17, or each functional component may be implemented by being distributed among a plurality of electronic circuits 17. FIG.

<Modification 3>
As a modified example 3, some functional components may be implemented by hardware, and other functional components may be implemented by software.

The processor 11 and the electronic circuit 17 are called a processing circuit. That is, the function of each functional component is realized by the processing circuit.

Note that "unit" in the above description may be read as "circuit", "process", "procedure", "process", or "processing circuit".

The embodiments and modifications of the present disclosure have been described above. Some of these embodiments and modifications may be combined and implemented. Also, any one or some may be partially implemented. It should be noted that the present disclosure is not limited to the above embodiments and modifications, and various modifications are possible as necessary.

REFERENCE SIGNS LIST 100 network system, 10 path control device, 11 processor, 12 storage device, 13 input/output interface, 14 distributor, 15 A/D converter, 16 changeover switch, 17 electronic circuit, 21 data acquisition unit, 22 determination unit, 23 path Switching unit 24 Notification unit 31 Setting data 32 Reference signal data 51 First device 52 Second device 53 Security device 60 Transmission line.

Claims (6)

A route control device that enables bypassing of a security device connected inline between a first device and a second device,
Based on the electrical waveform of the transmission signal sequence transmitted from the security device at the reference time, if the transmission signal sequence includes the reference signal sequence, the security device is determined to be normal, and the transmission signal sequence a determination unit that determines that the security device is not normal when the reference signal sequence is not included in the
When the determination unit determines that the security device is normal, communication data from one of the first device and the second device to the other is transmitted via the security device, and the determination unit a route switching unit that switches a route so that communication data from the one to the other is transmitted by bypassing the security device when it is determined that the security device is not normal. . The determination unit uses each of one or more partial signal sequences constituting the transmission signal sequence as a target partial signal sequence, and calculates a correlation coefficient between the target partial signal sequence and the reference signal sequence, 2. The routing control device according to claim 1 , wherein it is determined that said reference signal sequence is included in said transmission signal sequence when the correlation coefficient for at least one of the partial signal sequences exceeds a threshold value. 3. The route control device according to claim 1 , wherein the route control device is connected between the first device, the second device and the security device. The route control device further
4. The route control device according to any one of claims 1 to 3 , further comprising a notification unit that notifies a designated terminal when the security device is determined to be abnormal. A routing control method that enables bypassing of a security device connected inline between a first device and a second device,
Based on the electrical waveform of the transmission signal sequence transmitted from the security device at the reference time, if the transmission signal sequence includes the reference signal sequence, the security device is determined to be normal, and the transmission signal sequence determining that the security device is not normal when the reference signal sequence is not included in the
When the security device is determined to be normal, communication data from one of the first device and the second device to the other is transmitted via the security device, and it is determined that the security device is not normal. a route control method for switching a route so that communication data from the one to the other is transmitted by bypassing the security device when the security device is used. A routing control program that enables bypassing of a security device connected inline between a first device and a second device;
Based on the electrical waveform of the transmission signal sequence transmitted from the security device at the reference time, if the transmission signal sequence includes the reference signal sequence, the security device is determined to be normal, and the transmission signal sequence a determination process for determining that the security device is not normal when the reference signal sequence is not included in the
When the security device is determined to be normal by the determination processing, communication data from one of the first device and the second device to the other is transmitted via the security device, and the determination processing and a route control device for switching a route so that communication data from the one to the other is transmitted by bypassing the security device when it is determined that the security device is not normal. A routing program that allows a computer to function as a

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