JP5115724B2 - Communication failure avoidance method, information processing apparatus, and program - Google Patents

Description

  The present invention relates to a method for avoiding a communication failure caused by a generation error of an address conversion function of a network device in a system that communicates using a network device having an address conversion function, and an information processing apparatus and program using the method. .

  Recently, in order to solve the problem of exhaustion of addresses used for communication, various methods have been examined and many functions have been standardized.

  As one of the functions, an address translation function such as NAT (Network Address Translation) and NAPT (Network Address Port Translation) is implemented in many network devices.

  The NAT function is used for conversion between a local IP address and a global IP address in correspondence with main protocols such as TCP / IP and UDP / IP. The NAT function is implemented in, for example, a network device such as a broadband router, an ADSL modem, a DSU, or an optical line termination device.

  In the network device exemplified above, a device that converts a local IP address and a global IP address by using an address conversion function and simultaneously converts a port number used for communication is also commercially available. A network device having an address conversion function is described in, for example, Patent Documents 1 and 2. The combination of the IP address and the port number is called a socket.

  Patent Document 1 describes a communication method that solves the problem of the NAT function that cannot access a client terminal from the WAN side. Patent Document 2 describes a network device that solves an IPsec-specific problem in which a port number cannot be selected and performs address resolution.

The address conversion function in this specification refers to a function that realizes port number conversion or a socket conversion function together with IP address conversion.

  The techniques described in Patent Documents 1 and 2 and the proposed address conversion function record rules for converting addresses as a table, and perform address conversion processing based on the table. A rule for converting an address is created and recorded in a table at the time of the first communication or communication after a predetermined time has elapsed. It is also deleted when communication is not performed for a certain time.

  An example of a network configuration having such an address translation function is shown in FIG.

  FIG. 1 is a diagram illustrating a connection between a general client terminal and a server.

  The network configuration in FIG. 1 includes a plurality of client terminals 100, a broadband router (BB router) 200 having a NAT conversion function, and a server 300 that is a communication destination device. In such a configuration, by the NAT function of the broadband router 200, the same source address (source IP address), source port number (source port number), same destination address (destination IP address, destination IP address), destination When communication is performed using a nation port number (transmission destination port number, destination port number), the sequence is as shown in FIG. Communication between the client terminal 100 and the broadband router 200 is performed by wire or wireless. Note that the communication destination device of the client terminal 100 may be other than the server. For example, it may be a terminal that communicates via the Internet, or may be a terminal or server that belongs to another network.

  FIG. 2 is a sequence diagram showing an address conversion function in the network configuration of FIG.

(1) From the client terminal 100 to the broadband router 200 designated as the default route by the source address (192.168.1.10), the source port number (50000), the destination address (10.0.0.1), and the destination port number (50000) Send.

(2) The broadband router 200 rewrites the packet received in (1) from the source address (192.168.1.10) and source port number (50000) to the source address (10.0.0.2) and source port number (XXXX) The data is transmitted to the server 300 with the destination address (10.0.0.1) and the destination port number (50000).

(3) The server 300 processes the received packet of (2), and broadband with the source address (10.0.0.1), source port number (50000), destination address (10.0.0.2), and destination port number (XXXX) Transmit to the router 200.

(4) The broadband router 200 receives the packet received in (3) with the source address (10.0.0.1), source port number (50000), destination address (10.0.0.2), destination port number (XXXX) The data is rewritten to the destination address (192.168.1.10) and the destination port number (50000) and transmitted to the client terminal 100.

  The NAT conversion function of the broadband router uses the source address (192.168.1.10), source port number (50000), destination address (10.0.0.1), destination port number (50000) packets as source address (10.0.0.2) , Memorize the transmission with source port number (XXXX), destination address (10.0.0.1), destination port number (50000), so that source address (10.0.0.1), source port number (50000), destination Packets to destination address (10.0.0.2) and destination port number (XXXX) are source address (10.0.0.1), source port number (50000), destination address (10.0.0.2), destination address (192.168. 1.10), must be sent as the destination port number (50000) It can recognize that. The port number (XXXX) is arbitrarily determined by the broadband router 200 and may be transmitted as it is with the port number (50000) or may be rewritten to a completely different port number.

  In many commercially available broadband routers, the NAT table storing rules (management information) for NAT conversion (NAPT conversion) has the same source address, source port number, destination address, and destination port number for a certain period of time. If there is no communication, it is erased, and conversely, if there is communication within a certain time, it is held continuously. Specifically, a commercially available broadband router deletes the NAT table when there is no communication within the time of the NAT timer value (several minutes to several tens of minutes), and retains the NAT table when there is communication within that time. Is done.

  Thus, the client terminal 100 can acquire a response (response) from the server 300 to the transmitted packet (communication).

  Depending on the type of application software or client terminal, mutual communication is performed at predetermined intervals in order to prevent the network device from discarding the NAT table. This operation is used for maintaining a session.

  Normally, address conversion rules in a network device such as a broadband router are stored in a table and managed so as not to be erroneously created or damaged. In addition, the rules are implemented without considering incorrect creation or damage. Similarly, neither the client terminal nor the server can perform communication in consideration of erroneous creation or damage of the rule.

JP 2006-203575 A JP 2007-006109 A

  However, some network devices, such as commercially available broadband routers, miscreate or break rules (management information) for NAT conversion (NAPT conversion) due to software or hardware problems, communication failures, etc. There is.

  In the above-mentioned device in which the rule (management information) is erroneously created or damaged, normal address translation processing is not performed, and a response from the server to the packet from the client terminal cannot be received correctly.

  That is, a client terminal that communicates with a communication destination device via a network device that causes such a failure has a possibility that communication cannot be performed.

  In order to maintain a session, even if communication is performed using the same source address, source port number, same destination address, and destination port number with a predetermined transmission interval, Session disconnection occurs due to erroneous creation or corruption of device rules (management information).

  Further, if communication using a non-procedure method (for example, UDP) is used, the management information that caused the network device abnormality is permanently stored in order to continue communication without detecting malfunction of the address translation function. It falls into a state where it is not deleted.

  Further, even when viewed from the user of the client terminal, since there is no problem in the setting of the client terminal and the network device, the cause of the communication failure cannot be specified.

  FIG. 3 is a sequence diagram showing communication when the address conversion function in the network configuration of FIG. 1 has a defect.

  A specific example of the above problem will be described with reference to FIG. The sequence shown in FIG. 3 shows a case where the NAT table for operating the NAT function of the broadband router 200 is damaged, and address conversion from the WAN side to the LAN side cannot be performed correctly.

(1) From the client terminal 100 to the broadband router 200 designated as the default route by the source address (192.168.1.10), the source port number (50000), the destination address (10.0.0.1), and the destination port number (50000) Send.

(2) The broadband router rewrites the packet received in (1) from the source address (192.168.1.10) and source port number (50000) to the source address (10.0.0.2) and source port number (XXXX). The data is transmitted to the server 300 with the destination address (10.0.0.1) and the destination port number (50000).

(3) The server processes the received packet (2) and sends it with the source address (10.0.0.1), source port number (50000), destination address (10.0.0.2), and destination port number (XXXX). .

(4) Since the NAT management information is abnormal, the broadband router discards the packet received in (3) without recognizing which address and port the packet may be transmitted. There are various failure occurrence patterns, such as when a packet from the LAN side to the WAN side is discarded, or when a packet is transmitted to the WAN side at the wrong destination.

(5) Since there is no response from the server 300, the client terminal 100 performs a retransmission process similar to (1).

The operations (6) to (8) are the same as (2) to (4), and the packet is discarded.

  When there is an abnormality in the management information stored in the broadband router in this way, when the same source address, source port number, destination address, and destination port number are regularly used for retransmission, etc. In this case, the management information is kept in an abnormal state.

  Even if transmission retries are repeated due to a communication error, the management information of the broadband router continues to be held in an abnormal state, so that a state in which communication between the client terminal and the server cannot be continued continues. Although the communication can be normally performed by deleting the management information that has become abnormal, the function of deleting the management information from the client terminal to the broadband router is not implemented.

  In these cases, the user of the client terminal cannot take effective measures against the address translation failure of the broadband router.

  That is, when an information processing device such as a client terminal communicates via a network device having an address translation function, the communication retransmission process is simply performed due to a communication failure caused by an abnormality in the address translation function of the network device. In this case, since the address translation function causing the failure does not return to normal, the communication failure cannot be recovered. This cannot avoid a communication failure even if a protocol that realizes retransmission processing such as TCP is used.

  In view of the above problems, an object of the present invention is to provide an information processing apparatus capable of avoiding a communication failure at the time of a failure caused by management information used in an address conversion function of a network device.

  Another object of the present invention is to provide a communication failure avoidance method for avoiding a communication failure at the time of a failure caused by management information used in an address conversion function in a communication system communicating via a network device having an address conversion function.

  An information processing apparatus according to the present invention includes a communication unit that records a transmission source port number in a payload area of data used for communication and transmits a communication to a network device having an address conversion function, and a communication destination device for the communication to be transmitted Detection means for detecting communication of a response from the storage, and storage means for storing a predetermined retry count and / or a predetermined retry time for setting the communication retry, and the transmission source port number is determined as a predetermined retry. The transmission is changed and transmitted every number of times and / or every predetermined retry time.

  The communication failure avoidance method of the present invention is a communication failure avoidance method performed by an information processing device that records a transmission source port number in a payload area of data used for communication and sends out communication to a network device having an address conversion function. The control unit of the information processing device tries to detect a response from the communication destination device with respect to the transmitted communication, and the source port is determined for each retry count and / or retry time stored in advance. The number is changed and transmitted.

  ADVANTAGE OF THE INVENTION According to this invention, the information processing apparatus which can avoid a communication failure at the time of the failure resulting from the management information used with the address conversion function of a network device can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the communication failure avoidance method which avoids a communication failure at the time of the failure resulting from the management information used with the address conversion function in the communication system which communicates via the network device which has an address conversion function can be provided.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 is a block diagram illustrating a configuration of the client terminal 100 according to the embodiment. The client terminal 100 according to the present embodiment is a general personal computer. Even if it is not a personal computer, any information processing device that communicates with an external network via a network device having an address conversion function may be used. For example, a home appliance represented by an HDD recorder, a DVD recorder, or the like may be used. It may also be a security device that reports a warning or the like to a predetermined server.

  The client terminal 100 includes a control unit 110 that performs various types of information processing, a ROM 120 that stores a basic control program, a RAM 130 that temporarily stores information, an input unit 140 through which information is input by a user, and an output unit that outputs data and the like 150, a network interface 160 for performing communication with the Internet or the like via a network, an RTC unit 170 for realizing a clock function, and an HDD 180 as an auxiliary storage device are connected by a bus.

  A keyboard and mouse are connected to the input unit 140, and a user operation is input to the control unit 110. An LCD (Liquid Crystal Display) or the like is connected to the output unit 150 as a display device, and output information from the control unit 110 is output to the outside.

  The network interface 160 complies with various communication standards (protocols), and can communicate with the broadband router 200 or the like, which is a network device, using wired or wireless communication. In addition, a protocol suite 183 stored in the HDD 180, which will be described later, is used to transmit packets of protocols such as TCP / IP and UDP / IP.

  The RTC unit 170 is a circuit that realizes a clock function using a crystal oscillator or the like or an IC. The RTC unit 170 generates year, month, day, time information so as to be obtainable from the OS.

  The HDD 180 stores various programs and data files. An OS (Operating System) is also stored. The control unit 110 operates based on an instruction from the OS. In addition to the OS, the HDD 180 includes a communication program 181 such as a browser and a mail transmission / reception program, a retry condition setting value 182 that is the number of retries and a retry time, and a protocol suite that is data that enables communication in accordance with various protocols. 183 and the like are stored and expanded into the RAM 120 for use as necessary. The protocol suite 183 includes at least a protocol that can specify a port number or socket used for communication. For example, TCP, UDP, etc.

  Various communication programs and other software cooperate to make hardware such as the control unit 110 and the network interface 160 function as communication means, response detection means, means for changing port numbers, and the like. In addition, various communication programs obtain time information from the RTC unit 170 or the OS, detect a response from the communication destination, and use each source port number for avoiding communication failure. Functions that measure time from the time of communication failure and count the number of retries (connection retry counter, transmission retry counter) are implemented.

  In such a configuration, the client terminal 100 according to the embodiment of the present invention can avoid a communication failure at the time of a failure caused by management information used in the address translation function of the network device.

  The operation of the client terminal 100 will be described below. For the sake of clarity, the operation due to the protocol when performing communication is omitted.

  FIG. 5 is a flowchart showing an operation for setting the port number of the client terminal 100.

  Referring to the configuration of FIG. 1, as shown in FIG. 5, when the client terminal 100 communicates with the server 300 via the broadband router 200, the communication program 181 and the protocol suite 183 are used. Based on the retry condition setting value 182, the source port number (source port number) to be used is changed, and the packet is transmitted and retransmitted. Detailed operation will be described below.

  The control unit 110 of the client terminal 100 sets an initial value of the source port number according to the communication program 181 (step S501).

  The control unit 110 resets the connection retry counter according to the communication program 181 (step S502).

  Using the communication program 181 and the protocol suite 183, the control unit 110 transmits a packet in which an initial value of the source port number is set to the network device via the network interface 170, and performs connection processing to the server (step S503). .

  The control unit 110 attempts to detect a response (response) from the server that is the communication destination by the communication program 181 and proceeds to step S509 if it can be detected and connected (established a session), and proceeds to the next step if not detected (step) S504).

  The control unit 110 acquires time information from the OS or the like according to the communication program 181 and measures a response time from the server, and a response (response) until the retry time set in the retry condition setting value 182 is exceeded. ) Is tried (step S505).

  The control unit 110 adds a connection retry counter when there is no response (response) (step S506).

  In accordance with the communication program 181, the control unit 110 tries to connect to the server until the number of connection retries set in the retry condition set value 182 is exceeded, and proceeds to the next step when the number of retries exceeds the set value (step S507).

  The control unit 110 changes the source port number according to the communication program 181 and proceeds to step S502 (step S508). The source port number changing process may be incremented to an initial value number or may be changed to a predetermined number recorded in advance in the communication program 181.

  If the server can be connected, the control unit 110 determines whether there is a packet (actual data) to be transmitted. If there is a packet to be transmitted, the control unit 110 proceeds to the next step (step S509).

  The control unit 110 resets the transmission retry counter according to the communication program 181 (step S510).

  The control unit 110 uses the communication program 181 and the protocol suite 183 to transmit a packet describing the set source port number (step S511).

  The control unit 110 attempts to detect a response from the server using the communication program 181. If it can be detected and communicated, the control unit 110 proceeds to step S509. If not detected, the control unit 110 proceeds to the next step (step S512).

  The control unit 110 acquires time information from the OS or the like according to the communication program 181 and measures a response time from the server, and a response (response) until the retry time set in the retry condition setting value 182 is exceeded. ) Is tried (step S513).

  The control unit 110 adds a transmission retry counter when there is no response (response) (step S514).

  The control unit 110 attempts to retransmit communication to the server until the number of transmission retries exceeds the communication program 181. When the number of retries exceeds the set value, the control unit 110 proceeds to the next step (step S515).

  The control unit 110 disconnects the connection with the server according to the communication program 181 (step S516).

  The control unit 110 changes the source port number according to the communication program 181 and proceeds to step S502 (step S517). The source port number changing process may be incremented to the initial source port number or may be changed to a predetermined number recorded in advance in the communication program 181.

  Next, in order to explain the operation of the client terminal 100, a communication example in the configuration of FIG. 1 is shown. For the sake of clarity, the operation due to the protocol when performing communication is omitted.

  FIG. 6 is a sequence diagram illustrating the operation of the client terminal 100 in the network configuration of FIG.

  In the communication example of FIG. 6, communication is performed between the client terminal 100 and the server 300 using the same source address, source port number, same destination address, and destination port number. When the communication is normally performed, the operation is the same as the sequence diagram shown in FIG. FIG. 6 shows a case where a failure occurs in the address translation function of the broadband router 200 for some reason, and communication between the client terminal 100 and the server 300 becomes impossible.

  As in the sequence shown in FIG. 6, the client terminal 100 relays the broadband router 200 and communicates (1) to the server 300 using the same source address, source port number, same destination address, and destination port number. Then, based on the retry condition set in advance, the presence or absence of a response from the server 300 during the set value (approximately several seconds) is identified (the processing in S504 and S512 in FIG. 5).

  If there is no response and time-out (the processing of S505 and S513 in FIG. 5), transmission retry (retransmission) is performed several times (5) (the processing of S503 and S511 in FIG. 5). If it has exceeded (the processing in S507 and S515 in FIG. 5), the port number (source port number) of the client terminal 100 is changed from 50000 to 50001 (the processing in S508 and S517 in FIG. 5), and retransmission (9) is performed.

  By changing the port number of the client terminal 100 and transmitting (9), the address conversion function of the broadband router 200 newly generates management information, and performs address conversion based on the generated management information. . Since this address conversion is performed using newly generated management information without using erroneously created or damaged management information, the address conversion is normally performed. In the next communication, the client terminal 100 uses the same address and port number, so that the address is converted based on newly generated management information.

  The communication (12) from the server 300 whose address is normally translated normally reaches the client terminal 100. Similarly, the communication after (12) is normally performed.

  When a failure occurs in the management information used by the address conversion function of the broadband router 200, the management information that causes the communication abnormality is kept by simply repeating the retransmission process. Will not recover. Therefore, by changing the source port number of the client terminal 100 and changing the source port number and performing retransmission so that the management information that causes the failure of the address conversion function of the broadband router 200 is not used, the broadband router 200 is retransmitted. Even after a communication failure due to an abnormality in the management information, communication can be performed while avoiding the management information.

  As described above, according to this embodiment, even if a failure occurs in the management information of the address translation function in the network device, the failure can be automatically avoided so that communication is possible.

  The communication failure avoidance method according to the present embodiment does not require hardware and / or software changes in the communication destination device and the network device. That is, the existing communication infrastructure can be used as it is.

  In the description of the above embodiment, the port number to be changed has been described without any particular limitation. However, it is more efficient to limit the port number to a certain extent for implementing the communication program.

  In such a case, a predetermined port number may be used repeatedly. As a specific example, when a communication failure occurs while using the port number 50000, the port number is changed sequentially from the port number 50000 of the communication failure, and after the elapse of more than the automatic deletion time of the management information of the broadband router 200, the port Returning to the number 50000, a predetermined port number is repeatedly used.

  This expects that the management information inside the network device will be erased by making the communication state no longer than the automatic erasure time of the management information of the network device to be used.

  An operation example in such a case is shown in FIG.

  FIG. 7 is a sequence diagram illustrating an example of changing the port number. In this figure, three numbers (50000, 50001, 50002) used by the client terminal 100 as source port numbers are described. The number is not limited to three, and a necessary number is used from the occurrence of a failure until it returns to the initial value after elapse of more than the automatic deletion time of management information of the broadband router 200.

(1) Using the source address: 192.168.1.10, the source port: 50000, the destination address: 10.0.0.1, the destination port: 50000, the data is transmitted and received via the broadband router 200 between the client terminal 100 and the server 300. To do.

(2) to (5) A failure occurs in the address conversion function of the broadband router 200 for some reason, and communication between the client terminal 100 and the server 300 becomes impossible.

(6) to (9) The client terminal 100 changes the source port number from 50000 to 50001, avoids a failure, and starts communication with the servers 300. At this time, the communication program detects the failure of the port number 50000 and counts the time when the management information of the broadband router 200 will be automatically deleted.

(10) Using the source address: 192.168.1.10, the source port: 50001, the destination address: 10.0.0.1, the destination port: 50000, the data is transmitted and received via the broadband router 200 between the client terminal 100 and the server 300. .

(11) to (12) A failure occurs in the address conversion function of the broadband router 200 for some reason, and communication between the client terminal 100 and the server 300 becomes impossible.

(13) to (16) The client terminal 100 changes the source port number from 50001 to 50002, avoids a failure, and starts communication with the servers 300.

(17) Using the source address: 192.168.1.10, the source port: 50002, the destination address: 10.0.0.1, the destination port: 50000, the broadband router 200 is relayed between the client terminal 100 and the server 300 to transmit / receive data. .

(18) to (19) A failure occurs in the address conversion function of the broadband router 200 for some reason, and communication between the client terminal 100 and the server 300 becomes impossible.

(20) to (23) At this time, when the time when the management information of the port number 50000 that has been counted will be automatically deleted has elapsed, the client terminal 100 changes the source port number from 50002 to 50000 (initial value). ) To start communication with the server 300.

  As described above, by setting the port number to be used, the port number can be effectively used.

  The time when the management information will be automatically deleted may be determined for each network relay device to be used, or may be determined from the type or manufacturer of the network relay device. In addition, a time that is added to the maximum time for automatically deleting the management information of the existing product may be set.

  As described above, according to the present invention, it is possible to provide an information processing apparatus capable of avoiding a communication failure at the time of a failure caused by management information used in the address conversion function of the network device.

  Similarly, according to the present invention, it is possible to provide a communication failure avoidance method for avoiding a communication failure at the time of a failure caused by management information used in an address conversion function in a communication system that communicates via a network device having an address conversion function.

  In the embodiment described above, the information processing apparatus that communicates with the network apparatus having the address conversion function is described as a client terminal in FIG. 4, but the information processing apparatus has a configuration other than that illustrated in FIG. 4. Also, the configuration as shown in FIG. That is, the information processing apparatus may store various programs in the RAM 430 instead of the auxiliary storage device 180. Further, instead of the protocol suite 183, a protocol stack 433 adapted to the communication program to be used may be used. Such a configuration is suitable for an information processing device such as a security device that is forced to operate for a long time. The security device is required to have a long-term stable operation and a failure self-recovery function, and a function to avoid a relay failure of the network relay device along with other failure avoidance functions.

  In the above description, the communication program is described as changing the port number in a timely manner, but a program for changing the port number in a timely manner in the above-described scene may be provided as a program different from the communication program. Similarly, a program for realizing a method for avoiding the failure may be added to the protocol or the OS.

  Moreover, although the example which connects LAN and WAN was described in the said description, the connection of LAN and LAN may be sufficient.

It is a figure which illustrates the connection of a general client terminal and a server. It is a sequence diagram which shows the address conversion function in the network structure of FIG. FIG. 2 is a sequence diagram illustrating communication when the address conversion function in the network configuration of FIG. 1 has a defect. It is a block diagram which shows the structure of the client terminal of one Embodiment. It is a flowchart which shows the operation | movement which sets the port number of a client terminal. FIG. 2 is a sequence diagram illustrating an operation of a client terminal in the network configuration of FIG. 1. It is a sequence diagram explaining the example of a change of a port number. It is a block diagram which shows the structure of another client terminal of one Embodiment.

Explanation of symbols

100 Client terminal (information processing terminal)
110 Control unit 120 ROM
130 RAM (storage unit)
140 Input unit 150 Output unit 160 Network interface (communication unit)
170 RTC unit 180 HDD (storage unit)
181 Communication program
182 Retry condition setting value 183 Protocol suite 200 Broadband router (network device)
300 server (communication destination device)
400 Client terminal (information processing terminal)

Claims (15)

A communication unit that records a transmission source port number in a payload area of data used for communication and sends out communication to a network device having an address conversion function;
Detecting means for detecting communication of a response from a communication destination device for communication to be transmitted;
Storage means for storing a predetermined retry count and / or a predetermined retry time for setting the communication retry;
With
An information processing apparatus, wherein the transmission source port number is changed and transmitted every predetermined number of retries and / or every predetermined retry time. A control unit for performing various arithmetic processes;
A storage unit for storing a predetermined number of retries and / or a predetermined retry time;
A communication unit capable of packet communication with a network device having an address translation function using a network protocol capable of setting the network device and a source port number;
With
The controller is
Using the communication unit, send the packet by describing the source IP address and the first source port number in the header of the packet to be sent,
Based on the number of retries and / or the retry time stored in the storage unit, when there is no response to the transmitted packet, a source address and a second source port number are described in the header of the packet to be transmitted And sending the packet. The information processing apparatus according to claim 1 or 2,
The storage unit
Storing time information determined based on an automatic erasure time of management information used in the address conversion function of the network device ;
The controller is
An information processing apparatus that changes the transmission source port number based on the time information. An information processing apparatus according to any one of claims 1 to 3,
The network device is a broadband router;
The information processing apparatus, wherein the address conversion function is a NAT function.   5. The information processing apparatus according to claim 1, wherein the information processing apparatus is a security device. A communication failure avoidance method performed by an information processing device that records a transmission source port number in a payload area of data used for communication and sends out communication to a network device having an address conversion function,
A control unit of the information processing apparatus;
Attempt to detect a response from the destination device for the sent communication,
A communication failure avoidance method, wherein the transmission source port number is changed and transmitted for each retry count and / or retry time stored in advance. A communication failure avoidance method performed by an information processing apparatus capable of packet communication using a network protocol capable of setting a transmission source port number for a network apparatus having an address conversion function,
A control unit of the information processing apparatus;
Record the source IP address and the first source port number in the header of the sent packet and send the packet.
When there is no response to the transmitted packet, the source address and the second source port number are recorded in the header of the packet to be transmitted based on the number of retries and / or the retry time stored in advance. A communication failure avoiding method characterized by transmitting packets. The communication failure avoidance method according to claim 6 or 7,
A communication failure avoidance method, comprising: changing the transmission source port number based on time information determined based on an automatic erasure time of management information used in an address conversion function of the network device . A communication failure avoidance method according to any one of claims 6 to 8,
A communication failure avoidance method, wherein the network device is a broadband router, the address conversion function is a NAT function, and is used in the event of a failure caused by management information used in the NAT function.   10. The communication failure avoidance method according to claim 6, wherein the information processing device is a security device. For a network device having an address conversion function, a program used in an information processing device that records a transmission source port number in a payload area of data used for communication and sends out communication,
The control unit of the information processing device
A communication means for recording the transmission source port number in the payload area of data used for communication and sending the communication;
Function as a detection means for detecting communication of a response from a communication destination device for communication to be sent,
Furthermore, the program is made to function as means for changing the transmission source port number for each retry count and / or retry time stored in the storage unit. A program used in an information processing apparatus that enables packet communication using a network protocol capable of setting a source port number for a network apparatus having an address conversion function,
The control unit of the information processing device
A communication means for recording a transmission source IP address and a first transmission source port number in a header of a packet to be transmitted, generating a packet, and transmitting communication;
Function as a detecting means for detecting communication of a response from a communication destination device to the transmitted communication,
Further, when there is no response to the transmitted communication, the transmission source address and the second transmission source port number are added to the header of the packet to be transmitted based on the number of retries and / or the retry time stored in advance. A program that functions as means for recording and generating a packet. A program according to claim 11 or claim 12,
A program for changing the transmission source port number based on time information determined based on an automatic erasure time of management information used in the address conversion function of the network device . A program according to any one of claims 11 to 13,
A program characterized in that the network device is a broadband router, the address conversion function is a NAT function, and is used for avoiding a communication failure when a failure is caused by management information used in the NAT function.   15. The program according to claim 11, wherein the information processing device is a security device.

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