JP2010231310A - Time correction device, time correction system, time correction method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely notify a manager when a time difference between a system and an NTP server exceeds an allowable range due to the failure of an NTP server, without drastically modifying a time correction means on the system side. <P>SOLUTION: A time correction means 11 transmits a time correction request message to an NTP server 15, and calculates a time difference between a self system 10 and an NTP server 15, based on a time correction response message transmitted from the NTP server 15 in response to this message, and corrects the time of the self system based on the time difference. The time difference is stored in a database 14. When the time difference which is equal to or more than a predetermined threshold is stored in the database 14, a monitoring means 12 stops the time correction means, and issues an alarm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a time correction technique for synchronizing a system time with an accurate time.

  There are many systems such as billing servers and securities trading systems that require the system time to be synchronized with the correct time, and the following techniques are known as time correction techniques for such systems. (For example, refer to Patent Document 1).

  The technique described in Patent Document 1 uses an NTP (Network Time Protocol) server to synchronize the system time with Coordinated Universal Time (UTC). I have to. First, the time correction means on the system side (implemented by a program called an NTP client) transmits a time correction request message to the NTP server, and the NTP server that receives this transmits a time correction response message to the system. Send. When the time correction means in the system receives the time correction response message, the time correction means uses the time information (the transmission / reception time of the time correction request message and the transmission time of the time correction response message) contained therein to Calculate the time difference between the time and the current time of the NTP server (Coordinated Universal Time). Thereafter, the time correction means corrects the time of the own system using the calculated time difference, and transmits log information including the time difference to the NTP server.

  When receiving the log information, the NTP server determines whether or not the time difference included in the log information exceeds the allowable range. If it exceeds the allowable range, an out-of-allowance detection mail is transmitted to the system to notify the system administrator or the like that the time difference has exceeded the allowable range.

JP 2003-196170 A

  The technique described in Patent Document 1 described above has the following problems. When a failure occurs in the NTP server, the time information included in the time correction response message becomes invalid, and the time difference calculated using the incorrect time information may exceed the allowable range. However, in the technique described in Patent Document 1, the log information including the time difference is transmitted to the failed NTP server, and whether or not the time difference exceeds an allowable range in the failed NTP server. Since the determination is made, it may not be possible to detect that the time difference exceeds the allowable range, and an out-of-tolerance detection mail may not be transmitted. For this reason, there is a problem that a system administrator or the like cannot recognize that the time difference has exceeded the allowable range, and appropriate measures may not be taken.

  In order to solve such a problem, for example, it is determined whether or not the time difference exceeds the allowable range in the time correction means on the system side. A function for notifying may be incorporated, but in this case, a problem arises that the time correction means needs to be significantly modified.

(Object of invention)
Therefore, the object of the present invention is, even if the time correction means on the system side is not significantly modified, if the time difference between the current time of the system and the current time of the server exceeds the allowable range due to the failure of the server, An object of the present invention is to provide a time correction device that can notify an administrator of this fact with certainty.

The time correction apparatus according to the present invention is:
A time correction device included in a system connected to a server, and adjusts the time of the system to the time of the server,
Time correction means for calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system When,
The time difference storage unit is referred to, and when a time difference equal to or greater than a predetermined threshold is stored, a monitoring unit that issues an alarm is provided.

The time correction system according to the present invention is:
A system including a time correction device and a server;
The time correction device is
Time correction means for calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system When,
The time difference storage unit is referred to, and when a time difference equal to or greater than a predetermined threshold is stored, a monitoring unit that issues an alarm is provided.

The time correction method according to the present invention includes:
A first step of calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in a time difference storage unit, and correcting the current time of the own system; ,
A second step of issuing an alarm when a time difference equal to or greater than a predetermined threshold is stored with reference to the time difference storage unit.

The program according to the present invention is:
Time correction means for calculating the time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system A computer with
The time difference storage unit is referred to, and when a time difference equal to or greater than a predetermined threshold value is stored, the time difference storage unit functions as a monitoring unit that issues an alarm.

  According to the present invention, if the time difference between the current system time and the current server time exceeds the allowable range due to a server failure, the system-side time correction means is not significantly modified. Can be reliably notified to the administrator.

It is a figure which shows the structural example of 1st Embodiment of the time correction system concerning this invention. 3 is a flowchart showing an example of processing of the entire system 10. 5 is a flowchart showing a detailed processing example of authentication means 13. 4 is a flowchart showing a detailed processing example of a monitoring unit 12. It is a flowchart which shows the detailed process example of the monitoring means 12 in 2nd Embodiment of the time correction system concerning this invention. It is a flowchart which shows the detailed process example of the monitoring means 12 in 3rd Embodiment of the time correction system concerning this invention.

[First embodiment of the present invention]
Next, a first embodiment of a time correction system according to the present invention will be described in detail. Referring to FIG. 1, the time correction system according to the present embodiment includes a system 10, a plurality of NTP servers 15 to 17, and a certificate authority (CA) 18.

  The system 10 is a system such as a billing server or a securities trading system that requires strict time management, and includes a time correction unit 11, a monitoring unit 12, an authentication unit 13, and a database (DB) 14.

  In this embodiment, in order to make the time correction using NTP more reliable, the authentication unit 13 that assists the time correction unit 11 and the monitoring unit 12 are provided in the system 10.

  The time correction unit 11 transmits / receives a time correction request message and a time correction response message to / from any of the NTP servers 15 to 17 via the authentication unit 13 (it is desirable to communicate with a server having the shortest delay time). Based on the time information included in the response message, a time difference between the current time of the transmission source NTP server and the current time of the own system 10 is calculated, and the time of the own system 10 is calculated using the calculated time difference. A function of correcting (system clock) and a function of storing the calculated time difference in the database 14; The time correction means 11 is realized by executing a program called an NTP client by a CPU (Central Processing Unit; not shown).

  The authentication unit 13 has a function of detecting spoofing of a NTP server and alteration of a message using a public key encryption method when the system 10 performs time correction using the NTP servers 15 to 17 and NTP. The authentication unit 13 is a unit realized by executing an authentication program by the CPU.

  The monitoring unit 12 periodically monitors the time difference stored in the database 14 by the time correction unit 11 and stops the time correction unit 11 when a value that is determined to be abnormal is written. It has a function to raise an alarm. The monitoring unit 12 is a unit realized by executing a monitoring program by the CPU.

  The certificate authority 18 issues a public key certificate to the NTP servers 15-17. The NTP servers 15 to 17 have a function of distributing a public key certificate issued from the certificate authority 18 to the system 10 and transmitting / receiving a time correction request message and a time correction response message to / from the system 10.

[Description of Operation of First Embodiment]
Next, the operation of the present embodiment will be described in detail with reference to the flowchart of FIG.

  An NTP server (for example, the NTP server 15) is used for NTP encrypted communication to detect spoofing of an NTP server by a malicious third party and tampering of a time correction response message using a public encryption method. A key registration application is made to the certificate authority 18 and a request for issuing a public key certificate is made (step 200). In response to this, the certificate authority 18 performs a predetermined authentication registration procedure and issues a public key certificate to the NTP server 15 (step 201). Next, the NTP server 15 sends this public key certificate to the system 10 (step 202).

  The authenticating means 12 in the system 10 confirms the validity of the public key with this public key certificate (step 203), and thereafter performs NTP communication with the NTP server 15 using this public key.

  The time correction means 11 in the system 10 that performs time correction transmits a time correction request message to the NTP server 15 at certain intervals (step 204). At this time, since the authentication means 13 encrypts the time correction request message using the public key of the NTP server 15 (step 205), only the NTP server 15 having the secret key corresponding to the public key is the above-mentioned. A time correction request message can be processed. The time correction request message transmitted by the time correction unit 11 includes the transmission time t1.

  The NTP server 15 adds a digital signature and a message digest to the time correction response message for the time correction request message, encrypts it with its own secret key, and transmits it to the system 10 (step 206). The time correction response message includes the time correction request message transmission time t1 and reception time t2 and the time correction response message transmission time t3 as time information.

  Upon receiving the time correction response message, the authentication means 13 decrypts the message using the public key of the NTP server 15, and then checks whether the message has been tampered with and whether the message has been impersonated by a third party (step 207).

  FIG. 3 shows details of the operation performed by the authentication means 13 in step 207 of FIG. Upon receiving the time correction response message from the NTP server 15 (step 30), the authentication means 13 decrypts the time correction response message using the public key of the NTP server 15 (step 31). Next, the digital signature added in the time correction response message is confirmed to confirm that the NTP server 15 is not spoofed by a third party (step 32). If impersonation is detected, the time correction is performed. The response message is discarded (step 36). If not, the message digest is checked next, and it is confirmed that there is no tampering of the time correction response message by a third party (step 33). If tampering is detected, it is discarded as before (step 36). ). Note that a method for confirming the presence / absence of impersonation using a digital signature and a method for detecting falsification of a message using a message digest are generally well known, and will not be described. Finally, the state of the time correction unit 11 is confirmed (step 34). If the time correction unit 11 is operating, it can be ensured that the message is a normal time correction response message, so that it is transferred to the time correction unit 11. (Step 35). If the operation of the time correction unit 11 is stopped by the monitoring unit 12, the time correction response message is discarded (step 36). The above is the details of the processing performed in steps 207 and 208 of FIG.

  Returning to FIG. 2 again, when the normality of the time correction response message is confirmed by the confirmation in step 207, the authentication unit 13 transfers the time correction response message to the time correction unit 11 (step 208). Upon receiving this, the time correction means 11 determines the current time of the own system 10 and the current time of the NTP server 15 based on the time t4 at that time and the times t1 to t3 included in the time correction response message. The time difference including the time difference is stored in the database 14 (step 209). Then, the time correction unit 11 gradually approaches the time of the own system 10 to the time recorded by the NTP server 15 based on the time information stored in the database 14.

  On the other hand, the monitoring unit 12 sets the time correction unit 11 at regular intervals (in this embodiment, the time correction unit 11 uses the same cycle as the time correction request message but may be different). Reads the time information stored in the database 14 (step 210), determines the validity of the time information notified by the NTP server 15 (step 211), and stops the time correction means 11 when an abnormality is detected. The maintenance person is notified of the alarm (step 212).

  FIG. 4 shows details of the operation of the monitoring means 11. The monitoring unit 12 starts processing at a constant cycle (step 40), and first reads time information from the database 14 (step 41). This time information includes a time difference between the current time of the NTP server 15 and the current time of the system 10 itself. Here, the time correction unit 11 operates so as to gradually bring the time of the system 10 itself closer to the time recorded by the NTP server 15 each time an inquiry is made to the NTP server 15 (each time a time correction request message is transmitted). Therefore, the time difference should be smaller for each inquiry.

  When the time difference between the NTP server 15 and the system 10 is confirmed (step 42), if the value is smaller and improved than when the previous NTP server 15 was inquired, the processing is finished and the next monitoring cycle is completed. (Step 45). That is, when the time difference tends to decrease, it can be determined that a time correction response message including accurate time information has been sent from the NTP server 15, so that the confirmation unit 11 finishes the process and proceeds to the next. Wait until the monitoring cycle. When only one time information is registered in the database 14 (when the time correction processing by the time correction means 11 is performed only once), after executing step 41, step 42 is skipped. Step 43 is executed.

  On the other hand, if the time difference has become large and worse, it is checked whether or not the value is within an allowable range for the system 10 (a threshold value determined by a maintenance person at the time of system design) (step 43). If it is within the allowable range, the process is terminated and the next monitoring cycle is awaited (step 45). However, if the allowable range is exceeded, the NTP server 15 has not notified the accurate time information, and it is determined that further NTP communication is meaningless, and the time correction unit 11 is stopped (step 44). ) After that, time correction by NTP communication is not performed. At the same time, the maintenance person is notified of an abnormality in the NTP communication (step 44), and is made to take recovery measures such as confirming the state of the NTP server 15 to make an early recovery. In addition, when the time correction means 11 is stopped, in order to prevent the time of the system 10 from deviating greatly from the coordinated universal time, for example, the system clock is set to the real time clock, or the time of the system 10 is set to the real time clock Measures can be taken such as the time indicated.

[Effect of the first embodiment]
According to the present embodiment, the time difference between the current time of the system 10 and the current time of the NTP server 15 due to the failure of the NTP server 15 can be obtained without significantly modifying the time correction means 11 on the system 10 side. When the allowable range is exceeded, it is possible to obtain an effect that it is possible to notify the maintenance person of that without fail. The reason is that the time correction means 11 refers to the database 14 in which the time difference between the current time of the NTP server 15 and the current time of the system is stored, and a time difference exceeding a predetermined threshold is stored. This is because the time correction means 11 is stopped and the monitoring means 12 for issuing an alarm is provided.

  Moreover, according to this Embodiment, the useless traffic between the system 10 and the NTP server 15 can be eliminated. The reason is that when the time difference exceeding the threshold is stored in the database 14 (when a failure occurs in the NTP server 15), the time correction means 11 is stopped and communication with the NTP server 15 is performed. It is because it is made to stop.

  In addition, according to the present embodiment, it is possible to reliably prevent a situation in which the time of the system 10 is corrected by using a falsified time correction response message or a time correction response message by impersonation. An effect can be obtained. The reason is that an authentication unit that detects impersonation by a digital signature included in the time correction response message and detects falsification by a message digest is provided.

[Second Embodiment of the Present Invention]
Next, a second embodiment of the time correction system according to the present invention will be described. This embodiment is realized by causing the monitoring unit 12 to perform the process shown in the flowchart of FIG. 5 instead of the process shown in the flowchart of FIG.

  Referring to FIG. 5, the present embodiment is different from the first embodiment of the present invention in that the process of step 50 is performed before step 45. Only the differences will be described here. In step 50, the next monitoring cycle is determined based on the latest time difference stored in the database 14. More specifically, the smaller the time difference is, the longer the monitoring cycle is. That is, when the time difference is small, it is determined that the time correction is stably performed, and the monitoring cycle is lengthened. By doing in this way, the load accompanying time correction can be reduced.

[Effects of Second Embodiment]
According to the present embodiment, it is possible to reduce the load accompanying time correction. The reason is that as the latest time difference stored in the database 14 is smaller, the monitoring cycle is longer.

[Third embodiment of the present invention]
Next, a third embodiment of the time correction system according to the present invention will be described. This embodiment is realized by causing the monitoring unit 12 to perform the process shown in the flowchart of FIG. 6 instead of the process shown in the flowchart of FIG.

  Referring to FIG. 6, the present embodiment is different from the first embodiment of the present invention in that the processing of step 60 is performed before step 45. Here, only different points will be described. In step 60, the monitoring period is determined based on the latest time difference stored in the database 14 and the increasing / decreasing tendency of the time difference. More specifically, for example, it is determined from the latest time difference and the previous time difference whether the time difference stored in the database 14 is increasing or decreasing. Then, the shorter the latest time difference is, the longer the monitoring period is, and when the time difference is increasing, the monitoring period is determined so that the monitoring period is shorter than when it is decreasing. To do. As described above, when the time difference is small, it is considered that the time correction is performed stably, but even if the time difference is small, if it tends to increase, some abnormality has occurred. There is a risk of being. Therefore, in this embodiment, as described above, when the time difference tends to increase, the monitoring cycle is shortened, and if a failure occurs, it can be detected quickly.

[Effect of the third embodiment]
According to the present embodiment, it is possible to reduce a load associated with time correction and to quickly detect a failure. The reason is that the monitoring period is determined based on the time difference and the increasing / decreasing tendency thereof.

  The present invention is preferably applied to a system that requires strict time management, such as a billing server and a securities trading system.

DESCRIPTION OF SYMBOLS 10 ... System 11 ... Time correction means 12 ... Monitoring means 13 ... Authentication means 14 ... Database (DB)
15-17 ... NTP server 18 ... Certificate Authority (CA)

Claims (11)

A time correction device included in a system connected to a server, and adjusts the time of the system to the time of the server,
Time correction means for calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system When,
A time correction apparatus comprising: a monitoring unit that issues an alarm when a time difference equal to or greater than a predetermined threshold is stored with reference to the time difference storage unit. The time correction apparatus according to claim 1,
The monitoring means stops the time correction means when a time difference equal to or greater than the predetermined threshold is stored in the time difference storage unit. The time correction apparatus according to claim 1 or 2,
The time correction apparatus, wherein the monitoring unit refers to the time difference storage unit at a constant period. The time correction apparatus according to claim 1 or 2,
The monitoring means changes the reference cycle for the time difference storage unit based on the latest time difference stored in the time difference storage unit each time the time difference storage unit is referred to. Correction device. The time correction apparatus according to claim 1 or 2,
Each time the monitoring means refers to the time difference storage unit, the monitoring unit determines whether the time difference stored in the time difference storage unit tends to increase or decreases, and the determination result and the time difference A time correction apparatus that changes a reference cycle for the time difference storage unit based on the latest time difference stored in the storage unit. The time correction apparatus according to claim 4,
The time correction apparatus characterized in that the monitoring means lengthens the reference period for the time difference storage unit as the latest time difference is shorter. The time correction apparatus according to claim 5,
The monitoring means decreases as the reference time for the time difference storage unit becomes longer and the time difference stored in the time difference storage unit tends to increase as the latest time difference is shorter. The time correction apparatus characterized by changing the reference period for the time difference storage unit so that the reference period for the time difference storage unit is shorter than that in the case where there is a tendency. The time correction apparatus according to any one of claims 1 to 7,
The time information includes a digital signature and a message digest as additional information, and is encrypted with the secret key of the server,
The time correction device decrypts the time information with the public key of the server that is authenticated by a certificate authority, and then determines the presence or absence of impersonation using a digital signature and the presence or absence of falsification using a message digest. In addition, the time correction apparatus further comprises authentication means for passing the decrypted time information to the time correction means when there is no alteration. A system including a time correction device and a server;
The time correction device is
Time correction means for calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system When,
A time correction system comprising: a monitoring unit that issues an alarm when a time difference equal to or greater than a predetermined threshold is stored with reference to the time difference storage unit. A first step of calculating a time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in a time difference storage unit, and correcting the current time of the own system; ,
A time correction method comprising: a second step of issuing an alarm when a time difference equal to or greater than a predetermined threshold is stored with reference to the time difference storage unit. Time correction means for calculating the time difference between the current time of the server and the current time of the own system using the time information acquired from the server, storing the time difference in the time difference storage unit, and correcting the current time of the own system A computer with
A program for referring to the time difference storage unit and functioning as monitoring means for issuing an alarm when a time difference equal to or greater than a predetermined threshold is stored.

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