JP2019101950A - File transfer device, file transfer program, and file transfer method - Google Patents

Abstract

To safely transfer a file between systems.SOLUTION: First, a file transfer device 200 turns a state of a line switching device 110 into a first state in which connection to a first physical line 103 is made. Then the file transfer device 200 acquires a transferred file from a first system 101 as a connection destination of the first physical line 103. Then the file transfer device 200 turns the state of the line switching device 110 into a neutral state in which connection to neither the first physical line 103 and a second physical line 104 is made. Then the file transfer device 200 turns the state of the line switching device 110 into a second state in which connection to the second physical line 104 is made. Then the file transfer device 200 stores the transferred file into a second system 102 as a connection destination of the second physical line 104.SELECTED DRAWING: Figure 1

Description

  The present invention relates to secure file transfer.

Security devices such as firewalls are commercially available.
However, transferring files between systems via commercially available security devices poses the following risks.
(1) Remotely invade the other system via the security device.
(2) Data remaining from the non-volatile storage device provided in the security device is exploited.
(3) A file which should not be transferred is transferred unintentionally.

Patent Document 1 discloses a system for securely providing a file of a first computer of a first network for reading by a second computer of a second network.
In this system, both the first network and the second network are connected to the border network through a firewall.

Japanese Patent Application Publication No. 2016-517105

  The present invention aims to enable the secure transfer of files between systems.

The file transfer apparatus 200 of the present invention is
A switching control unit that controls the line switching device;
And a transfer unit for transferring a file via the line switching device.
The switching control unit sets the state of the line switching device to a first state connected to a first physical line,
The transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
After the transfer file is acquired, the switching control unit causes the state of the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
The transfer unit stores the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching device is brought into the second state.

The file transfer device includes an inspection unit that inspects the transfer file.
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching device is brought into the neutral state.
The switching control unit sets the state of the line switching device to the second state when transfer of the transfer file is permitted.

Inspection rules are stored on read-only media.
The inspection unit reads the inspection rule from the read only medium, and inspects the transfer file according to the inspection rule.

  The inspection unit inspects at least one of a file attribute of the transfer file and a data pattern included in the transfer file.

The file transfer device is
A communication port connected to the line switching device;
And a port control unit that controls the communication port.
The port control unit activates the communication port,
The transfer unit acquires the transfer file from the first system after the line switching device is brought into the first state and the communication port is activated.
The port control unit deactivates the communication port after the transfer file is acquired,
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching apparatus is brought into the neutral state and the communication port is deactivated.
The port control unit activates the communication port when transfer of the transfer file is permitted.
The transfer unit stores the transfer file in the second system after the line switching device is brought into the second state and the communication port is activated.

The file transfer device comprises volatile storage.
The transfer unit stores the transfer file in the volatile storage device after acquiring the transfer file from the first system.

The file transfer program of the present invention is
A switching control unit that controls the line switching device;
The computer functions as a transfer unit that transfers files via the line switching device.
The switching control unit sets the state of the line switching device to a first state connected to a first physical line,
The transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
After the transfer file is acquired, the switching control unit causes the state of the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
The transfer unit stores the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching device is brought into the second state.

The file transfer program further causes the computer to function as an inspection unit that inspects the transfer file.
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching device is brought into the neutral state.
The switching control unit sets the state of the line switching device to the second state when transfer of the transfer file is permitted.

Inspection rules are stored on read-only media.
The inspection unit reads the inspection rule from the read only medium, and inspects the transfer file according to the inspection rule.

  The inspection unit inspects at least one of a file attribute of the transfer file and a data pattern included in the transfer file.

The file transfer program further causes the computer to function as a port control unit that controls a communication port connected to the line switching device.
The port control unit activates the communication port,
The transfer unit acquires the transfer file from the first system after the line switching device is brought into the first state and the communication port is activated.
The port control unit deactivates the communication port after the transfer file is acquired,
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching apparatus is brought into the neutral state and the communication port is deactivated.
The port control unit activates the communication port when transfer of the transfer file is permitted.
The transfer unit stores the transfer file in the second system after the line switching device is brought into the second state and the communication port is activated.

  The transfer unit stores the transfer file in a volatile storage device after acquiring the transfer file from the first system.

In the file transfer method of the present invention,
The switching control unit changes the state of the line switching device to the first state connected to the first physical line,
A transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
The switching control unit causes the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line after the transfer file is acquired, and the line switching device is switched to the neutral state. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
The transfer unit stores the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching device is brought into the second state.

  According to the present invention, files can be securely transferred between systems.

FIG. 1 is a block diagram of a file transfer system 100 according to a first embodiment. FIG. 2 is a block diagram of a file transfer apparatus 200 according to the first embodiment. 6 is a flowchart of a file transfer method according to the first embodiment. FIG. 2 shows an initial state of the line switching device 110 according to the first embodiment. FIG. 2 shows a first state of the line switching apparatus 110 according to the first embodiment. FIG. 2 shows a neutral state of the line switching device 110 according to the first embodiment. FIG. 2 shows a second state of the line switching device 110 according to the first embodiment.

  In the embodiments and the drawings, the same elements and corresponding elements are denoted by the same reference numerals. Descriptions of elements with the same reference numerals will be omitted or simplified as appropriate. Arrows in the figure mainly indicate the flow of data or the flow of processing.

Embodiment 1
Secure fill transfer will be described based on FIGS. 1 to 7.

*** Description of the configuration ***
The configuration of the file transfer system 100 will be described based on FIG.
The file transfer system 100 is a system for transferring a file from the first system 101 to the second system 102.
Specifically, each of the first system 101 and the second system 102 is one or more computers.

The file transfer system 100 includes a first system 101, a second system 102, a line switching device 110, and a file transfer device 200.
The first system 101 is connected to the line switching device 110 via a first physical line 103. The first physical line 103 is a physical line that connects the first system 101 and the line switching device 110. A physical line is a physical line.
The second system 102 is connected to the line switching device 110 by a second physical line 104. The second physical line 104 is a physical line that connects the second system 102 and the line switching device 110.

The file transfer device 200 is connected to the line switching device 110 by the communication line 105 and the control line 106.
The communication line 105 is a signal line for communication, and connects the fourth port 114 of the line switching device 110 and the communication port 201 of the file transfer device 200.
The control line 106 is a signal line for control, and connects the fifth port 115 of the line switching device 110 and the control port 202 of the file transfer device 200.

The line switching device 110 is a general line switching device.
The line switching device 110 includes a plurality of ports. Specifically, the line switching device 110 includes five ports (111 to 115).
The first physical line 103 is connected to the first port 111.
The second physical line 104 is connected to the second port 112.
The physical line is not connected to the third port 113.
A communication line 105 is connected to the fourth port 114.
The control line 106 is connected to the fifth port 115.

The line switching device 110 includes a signal line 116.
One end of the signal line 116 is connected to any one of the first port 111, the second port 112, and the third port 113.
The other end of the signal line 116 is connected to the fourth port 114.

The configuration of the file transfer apparatus 200 will be described based on FIG.
The file transfer device 200 is a computer including hardware such as a processor 291, a volatile storage device 292, a communication interface 293, and a drive 294. These pieces of hardware are connected to each other via signal lines.

The processor 291 is an integrated circuit (IC) that performs arithmetic processing, and controls other hardware. For example, the processor 291 is a CPU (Central Processing Unit).
The volatile storage device 292 is a storage device that holds storage content only while power is supplied. For example, the volatile storage device 292 is a dynamic random access memory (DRAM). Volatile storage 292 is also referred to as main storage or main memory.
The communication interface 293 has a communication function, and includes a communication port 201 and a control port 202. For example, the communication interface 293 is a NIC (Network Interface Card).
The drive 294 is a device that reads data from a read only medium. For example, the drive 294 is an optical drive and the read only medium is an optical disc. A specific example of the optical disc is a compact disc read only memory (CD-ROM).

The processor 291 includes elements such as a switching control unit 211, a port control unit 212, a transfer unit 213, and an inspection unit 214. These elements are realized by software.
The switching control unit 211 controls the line switching device 110.
The port control unit 212 controls the communication port 201.
The transfer unit 213 performs file transfer via the line switching device 110.
The inspection unit 214 inspects the transfer file.

The read only medium stores a file transfer program for causing a computer to function as the switching control unit 211, the port control unit 212, the transfer unit 213, and the inspection unit 214. The file transfer program is loaded into volatile storage 292 and executed by processor 291.
Furthermore, an OS (Operating System) is stored in the read only medium. At least a portion of the OS is loaded into volatile storage 292 and executed by processor 291.
That is, the processor 291 executes the file transfer program while executing the OS.
Data obtained by executing the file transfer program is stored in a storage device such as a volatile storage device 292, a communication interface 293, a register in the processor 291, or a cache memory in the processor 291.

  The file transfer device 200 may include multiple processors that replace the processor 291. The multiple processors share the role of the processor 291.

  The file transfer program can be computer-readable (and read-only) recorded on a non-volatile recording medium such as an optical disk or flash memory.

*** Description of operation ***
The operation of the file transfer device 200 corresponds to a file transfer method. Also, the procedure of the file transfer method corresponds to the procedure of the file transfer program.

The file transfer method will be described based on FIG.
In step S101, the line switching device 110 switches the line to the first system 101 side.

The procedure of step S101 will be described.
The switching control unit 211 inputs the first switching instruction to the line switching device 110 via the control line 106 connected to the control port 202.
When the first switching instruction is input, the line switching device 110 switches the connection destination of the signal line 116 to the first port 111.
Thus, the state of the line switching device 110 transitions from the initial state (see FIG. 4) to the first state (see FIG. 5).

The initial state of the line switching device 110 will be described based on FIG.
In the initial state, neither the first physical line 103 nor the second physical line 104 is connected. The initial state is the same as the neutral state described later.

The first state of the line switching device 110 will be described based on FIG.
The first state is a state of being connected to the first physical line 103. The system to which the first physical line 103 is connected is the first system 101.

Returning to FIG. 3, the description will continue from step S102.
In step S102, the port control unit 212 of the file transfer apparatus 200 activates the communication port 201.
That is, the port control unit 212 makes the state of the communication port 201 valid. When the state of the communication port 201 is a valid state, communication can be performed via the communication port 201.

In step S103, the transfer unit 213 of the file transfer apparatus 200 acquires the transfer file from the first system 101.
The transfer file is a file (data) to be a file transfer target.

  Specifically, the first system 101 has a shared folder, and the transfer file is stored in the shared folder. The transfer unit 213 accesses the shared folder of the first system 101, and acquires the transferred file from the shared folder.

  In step S104, the transfer unit 213 of the file transfer device 200 stores the transfer file in the volatile storage device 292.

In step S105, the port control unit 212 of the file transfer apparatus 200 deactivates the communication port 201.
That is, the port control unit 212 makes the state of the communication port 201 invalid. If the communication port 201 is in an invalid state, communication can not be performed via the communication port 201.

  In step S111, the line switching device 110 disconnects the line.

The procedure of step S111 will be described.
The switching control unit 211 inputs a neutral switching command to the line switching device 110 via the control line 106 connected to the control port 202.
When the neutral switching command is input, the line switching device 110 switches the connection destination of the signal line 116 to the third port 113.
As a result, the state of the line switching device 110 transitions from the first state (see FIG. 5) to the neutral state (see FIG. 6).

The neutral state of the line switching device 110 will be described based on FIG.
In the neutral state, neither of the first physical line 103 and the second physical line 104 is connected.

Returning to FIG. 3, the description will continue from step S112.
In step S112, the inspection unit 214 of the file transfer apparatus 200 determines the transfer permission of the transfer file by inspecting the transfer file.

The procedure of step S112 will be described.
The drive 294 contains read only media. Inspection rules are stored on the read-only medium.
First, the inspection unit 214 reads the inspection rule from the read only medium.
Next, the inspection unit 214 inspects the transfer file according to the inspection rule.
Then, the inspection unit 214 determines the transfer permission of the transfer file based on the inspection result.

The inspection of the transfer file will be described.
The inspection unit 214 performs attribute inspection and pattern inspection on the transfer file.
Then, when the transfer file matches the inspection rule for attribute inspection and the transfer file matches the inspection rule for pattern inspection, the inspection unit 214 permits the transfer of the transfer file.
However, the inspection unit 214 may perform either the attribute inspection or the pattern inspection.

The attribute check is a check on the file attribute of the transfer file.
In the attribute inspection, the inspection unit 214 inspects the transfer file as follows.
The inspection unit 214 compares the size of the transfer file with the upper limit size. If the size of the transfer file is larger than the upper limit size, the inspection unit 214 does not permit transfer of the transfer file. The upper limit size is a check rule for attribute check and is read from read only media.
The inspection unit 214 compares the transfer file extension with the extension list. If the extension of the transfer file is not included in the extension list, the inspection unit 214 does not permit transfer of the transfer file. An extended list is a check rule for attribute checks, which is read from read-only media.
The inspection unit 214 compares the MIME type of the transfer file with the MIME type list. If the MIME type of the transfer file is not included in the MIME type list, the inspection unit 214 does not permit transfer of the transfer file. The MIME type list is a check rule for attribute check and is read from read-only media. MIME is an abbreviation for Multipurpose Internet Mail Extensions.

The pattern inspection is an inspection on data patterns included in the transfer file.
In pattern inspection, the inspection unit 214 inspects the transfer file as follows.
The inspection unit 214 compares the transfer file with the pattern file. When the data pattern registered in the pattern file is included in the transfer file, the inspection unit 214 does not permit the transfer of the transfer file. The pattern file is an inspection rule for pattern inspection and is read from a read only medium. The pattern file is also called a virus definition file, and computer virus and malware patterns are registered in the pattern file.
The inspection unit 214 compares the transfer file with the prohibited character string list. When the prohibited character string registered in the prohibited character string list is included in the transfer file, the inspection unit 214 does not permit the transfer of the transfer file. The forbidden string list is an inspection rule for pattern inspection and is read from a read only medium.

If transfer of the transfer file is permitted, the process proceeds to step S121.
If transfer of the transfer file is not permitted, the process proceeds to step S124.

  In step S121, the line switching device 110 switches the line to the second system 102 side.

The procedure of step S121 will be described.
The switching control unit 211 inputs a second switching instruction to the line switching device 110 via the control line 106 connected to the control port 202.
When the second switching instruction is input, the line switching device 110 switches the connection destination of the signal line 116 to the second port 112.
As a result, the state of the line switching device 110 transitions from the neutral state (see FIG. 6) to the second state (see FIG. 7).

The second state of the line switching device 110 will be described based on FIG.
The second state is a state in which the second physical line 104 is connected. The system to which the second physical line 104 is connected is the second system 102.

  In step S122, the port control unit 212 of the file transfer device 200 activates the communication port 201.

  In step S123, the transfer unit 213 of the file transfer apparatus 200 stores the transfer file in the second system 102.

  Specifically, the second system 102 has a shared folder. The transfer unit 213 accesses the shared folder of the second system 102 and stores the transferred file in the shared folder.

  In step S 124, the inspection unit 214 deletes the transfer file from the volatile storage device 292.

  In step S125, the port control unit 212 of the file transfer apparatus 200 deactivates the communication port 201.

In step S126, the line switching device 110 disconnects the line.
The procedure of step S126 is the same as the procedure of step S111.
As a result, the state of the line switching device 110 transitions from the second state (see FIG. 7) to the initial state (see FIG. 4).

  Steps S101 to S126 are executed for each transfer file. That is, steps S101 to S126 are repeated the same number of times as the number of transfer files.

*** Features of Embodiment 1 ***
The file transfer apparatus 200 acquires the transfer file from one system, inspects the transfer file based on a prohibited character string or a rule such as presence of malware, and then transfers the transfer file to the other system.
The file transfer device 200 has the following features.
(1) The file transfer device 200 physically separates the systems. That is, the file transfer device 200 is not always online with each system.
(2) The file transfer device 200 does not store the transfer file in the non-volatile storage device.
(3) The file transfer device 200 transfers only transfer files that have the specified file attributes (extension, MIME type, upper limit size) and do not include the defined pattern (malware pattern, prohibited character string) Do.
(4) The inspection rules are stored in the read only medium.

*** Effect of Embodiment 1 ***
The file transfer device 200 can transfer files securely between systems.
The file transfer apparatus 200 connects to the first physical line 103 only when acquiring a transfer file from the first system 101, and connects to the second physical line 104 only when storing a transfer file in the second system 102. This eliminates the risk of intrusion from one system to the other via the file transfer device 200.
The file transfer device 200 does not store the transfer file in the non-volatile storage device. This eliminates the risk of the transfer file being exploited.
The file transfer device 200 transfers only the transfer file permitted by the inspection. This eliminates the risk of unintentionally transferring files that should not be transferred.
The inspection rules are stored on a read only medium. This eliminates the risk that the inspection rules will be tampered with.

*** Supplement of the embodiment ***
The embodiments are exemplifications of preferred embodiments, and are not intended to limit the technical scope of the present invention. The embodiment may be partially implemented or may be implemented in combination with other embodiments. The procedure described using the flowchart and the like may be changed as appropriate.

  100 file transfer system, 101 first system, 102 second system, 103 first physical line, 104 second physical line, 105 communication line, 106 control line, 110 line switching device, 111 first port, 112 second port, 113 third port, 114 fourth port, 115 fifth port, 116 signal line, 200 file transfer device, 201 communication port, 202 control port, 211 switching control unit, 212 port control unit, 213 transfer unit, 214 inspection unit, 291 processor, 292 volatile storage, 293 communication interface, 294 drives.

Claims (13)

A switching control unit that controls the line switching device;
And a transfer unit for transferring a file via the line switching device;
The switching control unit sets the state of the line switching device to a first state connected to a first physical line,
The transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
After the transfer file is acquired, the switching control unit causes the state of the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
The transfer unit stores the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching device is brought into the second state. The file transfer device includes an inspection unit that inspects the transfer file.
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching device is brought into the neutral state.
The file transfer device according to claim 1, wherein the switching control unit sets the state of the line switching device to the second state when transfer of the transfer file is permitted. Inspection rules are stored on read-only media,
3. The file transfer apparatus according to claim 2, wherein the inspection unit reads the inspection rule from the read-only medium and inspects the transfer file according to the inspection rule. The file transfer device according to claim 2 or 3, wherein the inspection unit inspects at least one of a file attribute of the transfer file and a data pattern included in the transfer file. The file transfer device is
A communication port connected to the line switching device;
A port control unit that controls the communication port;
The port control unit activates the communication port,
The transfer unit acquires the transfer file from the first system after the line switching device is brought into the first state and the communication port is activated.
The port control unit deactivates the communication port after the transfer file is acquired,
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching apparatus is brought into the neutral state and the communication port is deactivated.
The port control unit activates the communication port when transfer of the transfer file is permitted.
5. The transfer system according to claim 2, wherein the transfer unit stores the transfer file in the second system after the line switching device is brought into the second state and the communication port is activated. The file transfer device according to item 1. The file transfer device comprises a volatile storage device;
The file transfer apparatus according to any one of claims 1 to 5, wherein the transfer unit stores the transfer file in the volatile storage device after acquiring the transfer file from the first system. A switching control unit that controls the line switching device;
A file transfer program for causing a computer to function as a transfer unit for transferring a file via the line switching device;
The switching control unit sets the state of the line switching device to a first state connected to a first physical line,
The transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
After the transfer file is acquired, the switching control unit causes the state of the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
The transfer program is a file transfer program for storing the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching apparatus is brought into the second state. The file transfer program further causes a computer to function as an inspection unit that inspects the transfer file.
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching device is brought into the neutral state.
8. The file transfer program according to claim 7, wherein the switching control unit sets the state of the line switching device to the second state when transfer of the transfer file is permitted. Inspection rules are stored on read-only media,
9. The file transfer program according to claim 8, wherein the inspection unit reads the inspection rule from the read-only medium and inspects the transfer file according to the inspection rule. 10. The file transfer program according to claim 8, wherein the inspection unit inspects at least one of a file attribute of the transfer file and a data pattern included in the transfer file. The file transfer program further causes a computer to function as a port control unit that controls a communication port connected to the line switching device.
The port control unit activates the communication port,
The transfer unit acquires the transfer file from the first system after the line switching device is brought into the first state and the communication port is activated.
The port control unit deactivates the communication port after the transfer file is acquired,
The inspection unit determines whether or not transfer of the transfer file is permitted by checking the transfer file after the line switching apparatus is brought into the neutral state and the communication port is deactivated.
The port control unit activates the communication port when transfer of the transfer file is permitted.
The transfer unit is configured to store the transfer file in the second system after the line switching apparatus is brought into the second state and the communication port is activated. File transfer program described in Section 1. The file transfer program according to any one of claims 7 to 11, wherein the transfer unit stores the transfer file in a volatile storage device after acquiring the transfer file from the first system. The switching control unit changes the state of the line switching device to the first state connected to the first physical line,
A transfer unit acquires a transfer file from a first system, which is a system to which the first physical line is connected, after the line switching device is brought into the first state;
The switching control unit causes the line switching device to be in a neutral state in which the line switching device is not connected to any of the first physical line and the second physical line after the transfer file is acquired, and the line switching device is switched to the neutral state. After being put into a neutral state, the line switching device is brought into a second state where it is connected to the second physical line,
A file transfer method, wherein the transfer unit stores the transfer file in a second system, which is a system to which the second physical line is connected, after the line switching device is brought into the second state.

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