JP2006094106A - Method and apparatus for redirection, and program thereof and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable realizing a redirection function in all communications without depending on an application, and to enable recognizing a correct redirection destination and a correct redirection source even when a redirection apparatus is connected to a plurality of external networks. <P>SOLUTION: A first redirection apparatus 1 transmits a negotiation request packet to a second redirection apparatus 2, and the second redirection apparatus 2 returns a negotiation response packet with the address of a communication apparatus 2. The first redirection apparatus 1 registers the address of the packet in a redirection table, and registers items of a redirection source address, a redirection destination address, a transmission source address, an application identifier, a session identifier and a redirection destination network identifier. These items are communicated between the first and second redirection apparatuses to normally recognize information of the transmission source and the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to packet communication technology, and in particular, when communication is started from a first point to a second point, the device at the second point moves to the third point with respect to the device at the first point. The present invention relates to a redirection method and apparatus for transferring communication, and a program and a recording medium thereof.

Conventionally, techniques such as HTTP (Hypertext Transfer Protocol) (see Non-Patent Document 1) have been proposed as a protocol for realizing redirection when communication is performed via an IP network such as the Internet. HTTP is described in RFC1945, and a server including a request command for a connection request is transmitted, and a server that receives the request command returns a packet including a response command as a response, but redirects to the location header of the response command. By including the URL indicating the destination, it is possible to notify the connection request side of the redirect destination. The connection request side notified of the redirect destination by the location header can retransmit the packet including the Request command to the redirect destination.
The feature of this method is expressed in an application layer, and an end-end communication device, that is, an application of a server or a client device negotiates.

HTTP "RFC1945 Hypertext Transfer Protocol ... HTTP / 1.0" (10.11 Location)

  As a proposal regarding the redirect technology, for example, Japanese Patent Application No. 2004-016931 and “Communication Method and Communication Device for Simultaneously Connecting to Multiple Networks” described in the drawings are available. According to a first aspect of the present invention, “the first communication device is connected to the second redirect device to the external network to start communication with the second redirect device via the first redirect device and the external network. The first redirect device transmits a negotiation request packet to the second redirect device triggered by reception of the connection request packet, and the second redirect device transmits the negotiation request packet to the second redirect device. When receiving the request packet, the second redirect device negotiates the address of the second communication device which is the new connection destination, that is, the redirect destination device in order to instruct the connection destination change, that is, the redirect instruction. A response response packet is transmitted to the first redirect device, and the first redirect device transmits the negotiation Receiving the response response packet, recognizing the redirect destination from the address of the redirect destination included in the received negotiation response packet, and thereafter, the first redirect device transmits the destination among the packets received from the first communication device. The first communication device is connected to the second communication device by converting the packet whose address is the address of the second redirect device, converting the destination address included in the packet to the redirect destination address, and transmitting it to the external network. The redirection method that enables the communication of “the communication” is described, and the same contents as described above are also described in the specification and the drawings.

In the proposed communication method, redirection is performed by performing negotiation between redirect devices and converting the destination address of the transmission packet.
However, there are the following problems (problems).
(Problem 1) Realization in the application layer needs to correspond to each application.
In HTTP, redirection is realized at the application level. Of course, communication using the Internet, which is one of the most representative external networks, is not limited to communication using HTTP, but other than FTP, SMTP, Communication is performed using various applications such as POP and DNS. In order to implement redirection at the application level, it must be specified and implemented for all applications to support redirection. Therefore, when trying to redirect various applications such as DNS server and mail server (SMTP, POP) with one communication device, all applications must be individually handled, and the protocol is still defined. For applications that do not, the protocol specification change for redirection is required for each application, and not only the software on the server side needs to be changed, but also the software on all clients to be used must be changed. End up.

(Problem 2) Communication cannot be continued.
FIG. 1 is a network configuration diagram showing a general connection configuration.
A redirect device 1, a redirect device 2, and a communication device 2 are connected to an external network such as the Internet. In addition, the communication device 1 is connected to the redirect device 1, and the communication device 1 communicates with other redirect devices, communication devices, and the like connected to the external network via the redirect device 1. In order to communicate via an external network, it is necessary to designate the address of the communication partner. When using an IP network such as the Internet, communication is performed by designating the IP address. For example, when Web surfing is performed, Web browser software is used as an application on the client side, and an IP address of a communication partner, that is, a Web server or a URL corresponding to the IP address is specified to start communication. Communication is performed by sending an IP packet whose destination address is the address of the Web server from the client side to the Web server that is the communication partner.
In FIG. 1, a personal computer equipped with a Web browser corresponds to the communication device 1, and a Web server corresponds to the redirect device 2 and the communication device 2.

FIG. 2 is a redirect sequence chart in FIG.
By using the method described in Japanese Patent Application No. 2004-016931 and the drawings, which is a redirection method by address translation, instead of a redirection method at the application level such as the HTTP location header, the communication device 1 uses the redirection device. A case where the communication device 1 communicates with the communication device 2 in response to a redirect request to the communication device 2 performed by the redirect device 2 will be described with reference to FIGS. 1 and 2.
The communication device 1 first transmits a connection request packet in which the destination address is set to the address of the redirect device 2 in order to communicate with the redirect device 2 (connection request packet (1)). However, even if the connection request packet reaches the redirect device 2, the redirect device 2 is originally set to redirect to the communication device 2, and thus the received connection request packet may be discarded. The redirect device 1 that has received the connection request packet (1) transmits a negotiation request packet to the redirect device 2 (negotiation request packet (2)), and instructs the communication device 2 to redirect from the redirect device 2. A negotiation response packet is received (negotiation response packet (3)).

Based on this instruction, the redirect device 1 thereafter transmits the packet whose destination address is the redirect device 2 among the packets transmitted from the communication device 1 to the external network side by converting the destination address into the address of the communication device 2. Perform the action. Since the communication device 1 has not received a response to the previously transmitted connection request packet (1), the application of the communication device 1 retransmits the connection request packet to the redirect device 2 (connection request packet (resend)). (Four)). The redirect device 1 that has received the connection request packet (retransmission) (4) identifies that the destination address is addressed to the redirect device 2, converts the destination address into the address of the communication device 2, and transmits it to the external network side. . (Connection request packet (retransmission) (5)).
By doing so, the connection request attempted by the communication device 1 is redirected to the communication device 2, and the packet can reach the communication device 2 safely. Therefore, it seems that the redirection is successful.

  However, a general application returns some response to the connection request. If it is HTTP, a Response command is returned in response to the Request command. Accordingly, the communication device 2 returns a connection response packet (6) in response to the connection request packet (retransmission) (5) and reaches the communication device 1. However, there is a problem that the source address of the connection response packet (6) becomes the address of the communication device 2. This is because although the communication device 1 has transmitted the connection request packet addressed to the redirect device 2, the transmission source address receives the connection response packet of the communication device 2. Since the application of the communication apparatus 1 discards connection response packets from different communication partners, communication cannot be continued with the method described in the above-mentioned Japanese Patent Application No. 2004-016931 and the drawings. That is, in this method, the reachability that the redirected packet can reach the redirect destination is realized, but the connectivity at the application level is not secured.

(Problem 3) New communication from the redirect destination cannot be identified.
FIG. 8 is a sequence chart illustrating an example in which the communication apparatus 1 cannot correctly recognize the communication partner when the redirect table is registered.
The redirect device 1 holds a redirect table that stores information related to redirect conditions. When a packet is received from the external network side, the redirect table is searched, and a record that matches the search condition, that is, the source address of the received packet is If it matches the redirect destination address, it is converted to the redirect source address indicated in the corresponding record of the source address and redirect table, and transmitted to the communication apparatus 1.

  When the redirect destination is a Web server or the like, no problem occurs because communication from the server to the client is not started. However, when the search condition is only the transmission source address and the table is registered so that the communication to the redirect device 2 is redirected to the communication device 2, the communication device 2 newly communicates with the communication device 1. When a packet is transmitted from the communication device 2 to the communication device 1 to start (connection request packet (1)), the redirect device 1 that receives the packet from the external network converts the source address to the redirect source address. Therefore, the communication device 1 determines that communication has been started from the redirect device 2 that is the redirect source device, and cannot be recognized as communication from the communication device 2 (see FIG. 8). That is, when a new communication start request is received from the redirect destination, it cannot be distinguished whether the request is a communication request from the redirect destination or a communication request from the redirect source.

(Problem 4) When a plurality of external networks are used, the correct redirect source cannot be recognized.
FIG. 12 is a diagram illustrating a device configuration and a network configuration when there are a plurality of external networks, and a redirect table.
Considering the case where the redirect device 1 is connected to a plurality of networks, not all of the plurality of networks are the Internet, but an individual network, that is, a network that is not connected to the Internet in order to provide a specific service. It is possible that there is.
As shown in FIG. 12A, since the individual network is not connected to the Internet, the global address is not used, and the use of a private address is assumed. Since the address system of the individual network using the private address is freely set by the administrator who operates the individual network, the same address may be used regardless of the different individual networks.

  For example, the redirect destination of the redirect device 2 belongs to the individual network 2 and the address is the communication device 2 of the address A, and the redirect destination of the redirect device 3 belongs to the individual network 3 and the address of the communication device 3 is the address A. In this case, when the redirect device 1 registers only the redirect destination address in the redirect table, the redirect table of the redirect device 1 is as shown in FIG. When the redirect device 1 receives a packet from the individual network and the packet with the address A is transmitted, whether the record 1 in the redirect table in FIG. 12B corresponds to the record 2 or not Send because it cannot be determined It is impossible to convert the address to the correct redirect source.

(the purpose)
The object of the present invention is to make it possible to realize the redirect function for all communications without depending on the application, and recognize the correct redirect destination and redirect source even when the redirect device is connected to multiple external networks. It is possible to provide a redirection method and apparatus, and a program and a recording medium thereof.

The redirection method of the present invention is as follows. (1) The first redirection device is physically or logically connected to an external network, has a first address assigned from the connected external network, and further includes a first communication. Connected to a first communication device having a second address for connecting to the device and having a different address;
The first communication device sends a connection request packet to the second redirect device to the external network to initiate communication with the second redirect device via the first redirect device and the external network;
The first redirect device transmits a negotiation request packet to the second redirect device triggered by reception of the connection request packet, and when the second redirect device receives the negotiation request packet. The second redirect device transmits a negotiation response packet in which the address of the second communication device, which is a new connection destination, that is, the redirect destination device, is written in order to perform a connection destination change instruction, that is, a redirect instruction. To the redirect device,
The first redirect device receives the negotiation response packet, recognizes the redirect destination from the redirect destination address included in the received negotiation response packet, and thereafter, the first redirect device transmits the first redirect device to the first redirect device. By converting a packet whose destination address is the address of the second redirect device from among the packets received from the communication device and converting the destination address included in the packet into the redirect destination address and transmitting the packet to the external network, the first In a redirection method that enables communication between the communication device and the second communication device,
The first redirect device holds a redirect table having “redirect source address” and “redirect destination address” as records, and receives the negotiation response packet as a trigger, and sets the destination address of the negotiation request packet as “ As a “redirect source address”, the address of the redirect destination communication device included in the negotiation response packet is stored as the “redirect destination address” in the record of the redirect table,
When the first redirect device receives a packet from an external network, the first redirect device searches the redirect table, and receives the packet when the source address of the received packet matches the “redirect destination address”. The transmission source address of the received packet is converted into the “redirect source address” of the matched record, and the packet is transferred to the first communication device.

In the redirect method of the present invention, (2) in the method (1), when the address of the communication device 1 cannot be used in an external network, the first redirect device configures the record of the redirect table. Holds a redirect table with "source address" added to the element,
The source address of the connection request packet that triggered the transmission of the negotiation request packet is set as a “source address”, the reception of the negotiation response packet is set as a trigger, and the destination address of the negotiation request packet is “redirected” As the “original address”, the address of the redirect destination communication device included in the negotiation response packet is stored in the record of the redirect table as the “redirect destination address”.
When the first redirect device receives a packet from an external network, the first redirect device searches the redirect table and receives the packet when the source address of the received packet matches the “redirect destination address”. The packet transmission destination address is converted to the “source address” of the matched record, and further the conversion process is performed to convert the source address to the “redirect source address” of the matched record, and the packet is sent to the first communication device. It is characterized by transferring.

The redirection method of the present invention (3) enables direct communication with the redirect destination in the method (1) or (2), and enables correct recognition that the communication is from the redirect destination. For,
The first redirect device holds a redirect table in which one or both of an “application identifier” and a “session identifier” are added to elements constituting the record of the redirect table,
An identifier indicating the type of application included in the connection request packet that is a transmission request packet of the negotiation request packet is stored in the record of the redirect table as an “application identifier” and an identifier indicating a session as a “session identifier”. ,
When receiving a packet from an external network, the first redirect device searches the redirect table, and in addition to the search condition and the matching condition shown in the method (1) or (2), When there is a record in which the identifier indicating the type of application and the identifier indicating the session match the “application identifier” and “session identifier” of the record, the conversion process shown in the method (1) or (2) is performed. The packet is transferred to the first communication device.

The redirection method of the present invention is (4) in the method (1) or (2),
When the external network is an IP network, the communication protocol is Internet Protocol, the redirect source address, the redirect destination address, and the source address that constitute the record of the redirect table are configured with IP addresses,
The first redirect device uses the destination IP address or the redirect source address indicated in the negotiation response packet included in the connection request packet that is a transmission trigger of the negotiation request packet as the “redirect source address”, the negotiation The redirection destination address indicated in the response packet is stored as the “redirection destination address” in the record of the redirection table, and in the case of the method (2), the connection that has been a transmission trigger for the negotiation request packet The source IP address included in the request packet is stored as the “source address” in the record of the redirect table,
The first redirect device searches the redirect table when receiving a packet from an external network, and transmits the packet when the source IP address of the received packet matches the “redirect destination address”. The original IP address is converted to the “redirect source address” of the matched record, and in the case of the method (2), the destination IP address of the received packet is converted to the “source address” of the matched record The conversion processing is performed, and the packet is transferred to the first communication device.

The redirection method of the present invention is (5) in the method (1) or (2),
In order to enable direct communication with the redirect destination when using TCP or UDP, in the configuration of the record of the redirect table shown in the method (4), the “application identifier shown in the method (3)” is further added. ”And“ session identifier ”are configured by adding two elements of“ IP protocol number ”and“ source port number ”that enable identification of TCP and UDP, respectively.
In addition to storing the redirect table in the record in the method (4), the first redirect device includes a protocol number of an IP header included in the connection request packet that is a transmission trigger of a negotiation request packet. “Application identifier”, in the case of TCP or UDP, the source port number included in the TCP or UDP header is stored as “session identifier” in the record of the redirect table,
The first redirect device searches the redirect table for the packet received from the external network, and in addition to the search condition of the method (1) or (2), the protocol number of the IP header of the received packet is “ When there is a record in which the application identifier and the destination port number match the “session identifier”, the conversion process shown in the method (4) is performed, and the packet is transferred to the first communication device. Yes.

Furthermore, the redirect method of the present invention is (6) in the method (1) or (2),
In the case where the first redirect device is connected to a plurality of networks, the first redirect device connected to a plurality of external networks is the redirect table shown in the methods (1) to (3). A redirect table with “redirect destination network identifier” added to the elements constituting the record is held, and the network identifier that is included in the received negotiation response packet and represents the network to which the redirect destination belongs is referred to as “redirect destination network identifier”. Store it in the record of the redirect table;
The first redirect device searches the redirect table when receiving a packet from an external network, and further receives a packet in addition to the search condition and the matching condition shown in the methods (1) to (3). When the external network has a record that matches the “redirect network identifier” of the record, the conversion processing shown in the methods (1) to (3) is performed, and the packet is transferred to the first communication device. It is characterized by.

According to the present invention, the redirect function can be realized in all communications without depending on the application.
Further, by changing the destination address of the packet received from the communication device and transmitting the packet to the external network, it is possible to obtain continuity of communication at the application level that cannot be realized by the method of realizing redirection.
In addition, by performing record management of the redirect table for each application and each session, it is possible to correctly recognize new communication from the redirect destination.
Furthermore, even when the redirect device is connected to a plurality of external networks, it is possible to recognize the correct redirect destination and each redirect source device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Network configuration)
FIG. 3 is a configuration diagram of a network to which redirect devices according to an embodiment of the present invention are connected.
The configuration of each device and external network is the same as that in FIG. When an IP network such as the Internet is used, communication is performed by specifying an IP address. In this case, the IP address of the interface connected to the external network of the redirect device is IP address 1, the redirect device 2, and the communication. The IP address of the device 2 is assumed to be IP address 2 and IP address 3, respectively. Further, the IP address of the interface connected to the communication device 1 of the redirect device 1 is assumed to be the IP address 11, and the IP address of the communication device 1 is assumed to be the IP address 12.

(Redirect table)
FIG. 4 is a configuration diagram of a redirect table according to an embodiment of the present invention.
The redirect table is composed of one or a plurality of records, and the record is composed of “redirect source address” and “redirect destination address”. In addition, “transmission source address”, “application identifier”, “session identifier”, and “redirect destination network identifier” may be added for each record.

(Packet conversion process flow)
FIG. 5 is an operation flowchart regarding the packet conversion processing of the redirect device.
The operation of the redirect device 1 transmits a connection request packet to the redirect device 2 in order for the communication device 1 to start communication with the redirect device 2 as in FIG. The source address and destination address of the connection request packet at this time are IP address 12 and IP address 2, respectively. The connection request packet transmitted by the communication device 1 reaches the redirect device 1, and when the redirect device 1 identifies that the destination address of the connection request packet is IP address 2, the source address is IP address 1, and the destination address is IP address. 2 negotiation request packet is generated and transmitted to the redirect device 2.

The negotiation request packet reaches the redirect device 2 via the external network, and the redirect device 2 instructs the redirect to the communication device 2, so that the source address and the destination address including the IP address 3 that is the redirect destination are respectively The negotiation response packet of IP address 2 and IP address 1 is returned to the redirect device 1. Up to this point, the process is the same as in FIG.
The redirect device 1 that has received the negotiation response packet sets the transmission source address of the negotiation response packet, that is, the IP address 2 as the “redirect source address” of the record, and the redirect destination address included in the negotiation response packet That is, the IP address 3 is set as the “redirect address” of the record.

The operation of the packet conversion process of the redirect device 1 after the record is added to the redirect table is as shown in FIG. FIG. 5A shows an operation when a packet is received from the communication apparatus, and FIG. 5B shows an operation when a packet is received from an external network.
When a packet is received at the interface connected to the communication device, as shown in FIG. 5A, the destination address of the packet is recognized, and all records in the redirect table are searched. If there is a record that matches “address”, that is, if there is a record whose IP address 2 is “redirect source address” (step 101), the destination address is the address indicated in “redirect destination address” of the record, That is, the IP address 3 is converted (step 102), and the packet is transmitted to the external network (step 103). On the other hand, when there is no record that matches the “redirect source address”, negotiation is activated and a negotiation request packet is transmitted (step 104).

  On the other hand, when a packet is received at an interface connected to an external network, as shown in FIG. 5B, the source address of the packet is recognized, all records in the redirect table are searched, and the source address is searched. If there is a record that matches the “redirect source address”, that is, if there is a record whose “redirect source address” is IP address 3 (step 201), the source address is set to the “redirect source” of the record. It is converted into the address indicated by “address”, that is, IP address 2 (step 202), and the packet is transmitted to the communication apparatus 1 (step 203).

Example 1
FIG. 6 is a sequence chart of the redirection operation according to the first embodiment of the present invention.
In order to communicate with the redirect device 2, the communication device 1 transmits a connection request packet in which the destination address is set to the IP address 2 that is the address of the redirect device 2 (connection request packet (1)). However, even if the connection request packet reaches the redirect device 2, the redirect device 2 is originally set to redirect to the communication device 2, and therefore the received connection request packet may be discarded.
The redirect device 1 that has received the connection request packet (1) transmits a negotiation request packet to the redirect device 2 with the IP address 2 (negotiation request packet (2)), and the redirect device 2 transmits to the communication device 2. That is, a negotiation response packet instructing redirection to IP address 3 is received (negotiation response packet (3)).

  Based on this instruction, the redirect device 1 registers the “redirect source address” in the redirect table as the IP address 2 and the “redirect destination address” as the IP address 3 in the record. Thereafter, a packet whose destination address matches the “redirect source address” in the redirect table record among the packets transmitted from the communication device 1, that is, the packet of the IP address 2 whose destination address is the address of the redirect device 2 is received. In this case, the destination address is converted to the address of the communication device 2 that is the “redirect destination address” of the corresponding record, that is, the IP address 3, and transmitted to the external network side.

Since the communication device 1 has not received a response to the previously transmitted connection request packet (1), the application of the communication device 1 retransmits the connection request packet to the redirect device 2 (connection request packet (resend)). (Four)).
The redirect device 1 that has received the connection request packet (retransmission) searches the redirect table. Since the packet having the destination address matching the “redirect source address” of the record of the redirect table, that is, the packet of the IP address 2 whose destination address is the address of the redirect device 2, is received, the “redirect destination address” of the corresponding record Is converted to the address of the communication device 2, that is, the IP address 3 and transmitted to the external network side (connection request packet (retransmission) (5)).

The redirect device 1 that has received the connection response packet (6) searches the redirect table, and there is a record in which the source address of the received packet matches the IP address 3 that is the “redirect destination address” of the record in the redirect table. The transmission source address is converted into the “redirection source address” of the corresponding record in the redirect table, that is, the IP address 2 which is the address of the redirect device 2, and transmitted to the communication device 1 (connection response packet (7)).
In this way, it is possible to receive a connection response packet whose source address is IP address 2 for a connection request packet whose destination address is IP address 2, and to continue communication even at the application level. Become.

(Example 2)
FIG. 7 is a sequence chart of the redirect operation according to the second embodiment of the present invention.
The underlined portion in FIG. 7 indicates an operation that is different from that in FIG.
In FIG. 3, the redirect device 1 is described assuming installation in a user's house or the like, and generally a home broadband router is assumed. In such a case, although the global IP address assigned from the external network is used as the IP address 1, the IP address 11 and the IP address 12 generally use private addresses that can be arbitrarily set by the user. . In this case, as a matter of course, communication must be performed using the global address on the external network side, and communication must be performed using the private address between the redirect device 1 and the communication device 1, so that address conversion is necessary. .
A series of sequences in this case is shown in FIG.

7, the redirect device 1 is the same as FIG. 6 of the first embodiment until the negotiation response packet (3) is received. At this time, “source address” is added to the redirect table record of the first embodiment. That is, when a record is added to the redirect table, the IP address 12 that is the transmission source IP address of the connection request packet that has triggered the transmission of the negotiation request packet together with the “redirection source address” and the “redirection destination address”. Register in “Sender Address”.
When the redirect device 1 receives a packet (connection request packet (retransmission) (4)) from the communication device 1, the destination IP address of the packet matches the “redirect source address” of the redirect table, that is, the IP address 2, and Since the source IP address of the packet matches the “source address”, the source address is converted to IP address 1 which is its own IP address, and the destination address is converted to IP address 3 which is the “redirect destination address”. To the external network side (connection request packet (retransmission) (5)).

When the redirect device 1 receives a packet (connection response packet (6)) from the external network, the redirect device 1 searches the redirect table. Since the source address matches the IP address 3 that is the “redirect destination address” of the record in the redirect table, the source address is the “redirect source address” of the corresponding record in the redirect table, that is, the IP that is the address of the redirect device 2. The address is converted to address 2, and the destination address is further converted to the “source address” of the corresponding record, that is, the IP address 12 that is the address of the communication apparatus 1 and transmitted to the communication apparatus side (connection response packet (7)). .
In this way, even when a private address is used for the communication device 1, it is possible to receive a connection response packet whose source address is IP address 2 in response to a connection request packet whose destination address is IP address 2. Thus, communication can be continued even at the application level.

(Example 3)
FIG. 9 is a sequence chart of the redirection operation according to the third embodiment of the present invention.
In this embodiment, in order to solve the problem that the communication apparatus 1 cannot correctly recognize the communication partner when the redirect table is registered in the first and second embodiments, the “application identifier” and the “session” are included in the redirect table. This is an example using “identifier”.
The procedure for adding a record to the redirect table in the redirect device 1 is the same as in the first and second embodiments, but the redirect device 1 specifies the protocol number included in the packet IP header received from the communication device 1 as “application identifier”. The transmission source port number is registered together with the “session identifier”. Here, in the redirect table record, IP address 2 as “redirect source address”, IP address 3 as “redirect destination address”, TCP as “application identifier”, and 54321 which is the source port number as “session identifier” Assume that each is set.

FIG. 10 is an operation flowchart of packet conversion processing of the redirect device according to the third embodiment.
Here, the redirect device 1 is an IP packet for newly starting communication with the communication device 1 from the communication device 2 connected to the external network, the destination address is the IP address 12, and the transmission source address is the IP address 3. Assume that an IP packet having a protocol number of TCP and a destination port number of “55555” is received.
The redirect device 1 searches the redirect table as shown in FIG. Since the IP address 3 whose source address is “redirect source address” and the TCP whose protocol number is “application identifier” match, the destination port number does not match 54321 which is “session identifier”. The IP address is not converted to IP address 2 which is the “redirect source address”. Therefore, since the source address of the IP address delivered to the communication device 1 is the IP address 3 of the communication device 2, the communication device 1 can recognize that the communication is from the communication device 2.

As is apparent from a comparison between FIG. 10A and FIG. 5A, in the third embodiment, in addition to the steps in FIG. 112) and a process for determining whether or not the transmission source port number and the session identifier match (step 113).
Further, as apparent from a comparison between FIG. 10B and FIG. 5B, in the third embodiment, in addition to the steps in FIG. 5, a determination process for determining whether or not the protocol number and the application identifier match. (Step 212) and determination processing (Step 213) for determining whether or not the destination port number and the session identifier match are added.

Example 4
FIG. 13 is a sequence chart of the redirect operation according to the fourth embodiment of the present invention, and FIG. 14 is a configuration diagram of a record of the redirect table in the fourth embodiment.
In this embodiment, when the redirect device is connected to a plurality of external networks, the problem that the source address cannot be returned to the correct redirect source address can be solved by using the “redirect destination network identifier”.
In the configuration illustrated in FIG. 12, the redirect device 1 receives an negotiation response packet from the redirect device 3 that is the redirect source and the address is the IP address 3, and thus is an identifier NW 3 that represents the individual network 3 as the redirect destination network. A case where the IP address A which is the address of the communication device 3 is designated as the redirect destination address will be described.

As shown in FIG. 14, the redirect device 1 adds a record of NW3 to the “redirect destination network identifier” and the IP address A to the “redirect destination address” of the redirect table.
As shown in FIG. 13, the redirect device 1 searches the redirect table when the connection response packet (6) whose source address is address A is received from the individual network 3, and the “redirect destination network identifier” is the connection response packet. Since there is a record that matches NW3 that is the network that received (5) and that matches the IP address A whose source address is the “redirect destination address”, the redirect source address is identified as IP address 3, A connection response packet (7) in which the transmission source address is converted to the IP address 3 is transmitted to the communication device 1.
As described above, by using the “redirect destination network identifier”, a correct redirect source can be recognized even when there are a plurality of external networks.

(Example 5)
The present embodiment is a case where the redirect device is installed as equipment on the network side.
In the first to fourth embodiments, as illustrated in FIGS. 3 and 12, the redirect device is described as an example of a configuration installed in a user's home. However, as shown in FIGS. 11 (a) and 11 (b), it is also obvious that redirection can be realized without making the user aware of redirection as equipment on the network side.
With such a configuration, a telecommunications carrier that operates an external network and a carrier that provides an access service using an access network for connecting to the external network can also perform a redirect service.

(Program and recording medium)
The flow of the packet conversion process in FIG. 5, the redirect sequence in the first embodiment in FIG. 6, the redirect sequence in the second embodiment in FIG. 7, the redirect sequence in the third embodiment in FIG. 9, and the packet conversion process in the third embodiment in FIG. If each operation step of the flow and the redirect sequence of the fourth embodiment shown in FIG. The present invention can be easily realized by installing the redirect device shown in the computer and installing and executing the program. In addition, the program of the present invention can be widely generalized by downloading the program to many other computers via a network.

  By using the redirect method and apparatus of the present invention as described above, communication by the communication method described in the first to fifth embodiments becomes possible.

It is a block diagram of a device configuration and a network configuration that give a problem to be solved. It is a sequence chart of the redirection operation | movement of a prior art. 1 is a block diagram of a device configuration and a network configuration that are the basis of the present invention. FIG. It is a block diagram of the redirect table of this invention. It is an operation | movement flowchart of the packet conversion process of the redirect apparatus by this invention. It is a sequence chart of the redirection operation | movement which concerns on Example 1 of this invention. It is a sequence chart of the redirection operation | movement which concerns on Example 2 of this invention. It is a figure which shows the example in which the communication apparatus 1 cannot recognize a communication other party correctly, when the redirect table is registered. It is a sequence chart of the redirection operation | movement which concerns on Example 3 of this invention. 9 is an operation flowchart of packet conversion processing of the redirect device 1 in the third embodiment. It is a figure which shows the redirect apparatus which concerns on Example 5 of this invention, and its network structure. It is a block diagram of a device configuration and a network configuration when there are a plurality of external networks. It is a sequence chart of the redirection operation | movement which concerns on Example 4 of this invention. Similarly, it is the record block diagram of the redirect table which concerns on Example 4. FIG.

Explanation of symbols

IP address 1 ... network interface address of redirect device 1 IP address 2 ... network interface address of redirect device 2 IP address 3 ... network interface address of communication device 2 IP address 11 ... redirect device 1 communication device side interface address IP address 12... Redirection device side interface address of communication device 1 NW3... Individual network 3 identifier

Claims (17)

The first redirect device is physically or logically connected to the external network, has a first address assigned from the connected external network, and further has a second address for connecting to the first communication device Connected to a first communication device having a different address,
The first communication device sends a connection request packet to the second redirect device to the external network to initiate communication with the second redirect device via the first redirect device and the external network;
The first redirect device transmits a negotiation request packet to the second redirect device triggered by reception of the connection request packet, and when the second redirect device receives the negotiation request packet. The second redirect device transmits a negotiation response packet in which the address of the second communication device, which is a new connection destination, that is, the redirect destination device, is written in order to perform a connection destination change instruction, that is, a redirect instruction. To the redirect device,
The first redirect device receives the negotiation response packet, recognizes the redirect destination from the redirect destination address included in the received negotiation response packet, and thereafter, the first redirect device transmits the first redirect device to the first redirect device. By converting a packet whose destination address is the address of the second redirect device from among the packets received from the communication device and converting the destination address included in the packet into the redirect destination address and transmitting the packet to the external network, the first In a redirection method that enables communication between the communication device and the second communication device,
The first redirect device holds a redirect table having “redirect source address” and “redirect destination address” as records, and receives the negotiation response packet as a trigger, and sets the destination address of the negotiation request packet as “ As a “redirect source address”, the address of the redirect destination communication device included in the negotiation response packet is stored as the “redirect destination address” in the record of the redirect table,
When the first redirect device receives a packet from an external network, the first redirect device searches the redirect table, and receives the packet when the source address of the received packet matches the “redirect destination address”. A redirection method comprising: performing a conversion process for converting a transmission source address of a received packet into a “redirection source address” of the matched record, and transferring the packet to the first communication device. The redirect method according to claim 1, wherein:
When the address of the first communication device cannot be used in an external network, the first redirect device holds a redirect table in which “source address” is added to the elements constituting the record of the redirect table,
The source address of the connection request packet that triggered the transmission of the negotiation request packet is set as a “source address”, the reception of the negotiation response packet is set as a trigger, and the destination address of the negotiation request packet is “redirected” As the “original address”, the address of the redirect destination communication device included in the negotiation response packet is stored in the record of the redirect table as the “redirect destination address”.
When the first redirect device receives a packet from an external network, the first redirect device searches the redirect table and receives the packet when the source address of the received packet matches the “redirect destination address”. The packet transmission destination address is converted to the “source address” of the matched record, and further the conversion process is performed to convert the source address to the “redirect source address” of the matched record, and the packet is sent to the first communication device. A redirection method characterized by transferring a message. The redirection method according to claim 1 or 2,
In order to enable direct communication with the redirect destination and to correctly recognize that the communication is from the redirect destination,
The first redirect device retains a redirect table in which one or both of an “application identifier” and a “session identifier” are added to the elements constituting the record of the redirect table,
An identifier indicating the type of application included in the connection request packet that is a transmission request packet of the negotiation request packet is stored in the record of the redirect table as an “application identifier” and an identifier indicating a session as a “session identifier”. ,
When the first redirect device receives a packet from the external network, the first redirect device searches the redirect table, and in addition to the search condition and the matching condition shown in claim 1 or 2, further represents the type of application of the received packet. When there is a record whose identifier and session identifier match the “application identifier” and “session identifier” of the record, the conversion process shown in claim 1 or 2 is performed and the packet is transferred to the first communication device A redirection method characterized by: The redirection method according to claim 1 or 2,
When the external network is an IP network, the communication protocol is Internet Protocol, the redirect source address, the redirect destination address, and the source address constituting the record of the redirect table are configured with IP addresses, and the first redirect device Is a destination IP address included in the connection request packet that is the transmission trigger of the negotiation request packet or a redirect source address indicated in the negotiation response packet is “redirect source address”, and is indicated in the negotiation response packet The redirection destination address is stored as the “redirection destination address” in the record of the redirection table, and in the case of the method according to claim 2, a negotiation request packet is stored. The source IP address included in the connection request packet that bets transmission trigger as the "source address" stored in the record of the redirection table,
The first redirect device searches the redirect table when receiving a packet from an external network, and transmits the packet when the source IP address of the received packet matches the “redirect destination address”. 3. The original IP address is converted to the “redirect source address” of the matched record, and in the case of the method of claim 2, the destination IP address of the received packet is converted to the “source address” of the matched record. A redirection method comprising: performing a conversion process and transferring a packet to a first communication device. The redirection method according to claim 1 or 2,
In order to enable direct communication with a redirect destination when using the TCP or UDP, in the structure of the redirect table record shown in the method of claim 4, further shown in the method of claim 3. As an “application identifier” and a “session identifier”, it is composed of elements added with two elements of “IP protocol number” and “source port number” that enable identification of TCP and UDP, respectively.
The first redirect device includes a protocol of an IP header included in the connection request packet that is a transmission trigger of a negotiation request packet, in addition to storing the redirect table in the record according to the method of claim 4 The number is “application identifier”, and in the case of TCP or UDP, the source port number included in the TCP or UDP header is stored as “session identifier” in the record of the redirect table,
The first redirect device searches a redirect table for a packet received from an external network, and in addition to the search condition of the method according to claim 1 or 2, the protocol number of the IP header of the received packet is further determined. When there is a record in which the “application identifier” and the destination port number match the “session identifier”, the conversion processing shown in the method of claim 4 is performed, and the packet is transferred to the first communication device. Feature redirect method. The redirection method according to claim 1 or 2,
The first redirect device connected to a plurality of external networks for the case where the first redirect device is connected to a plurality of networks, the first redirect device of the redirect table shown in any one of claims 1 to 3 A redirect table with “redirect destination network identifier” added to the elements constituting the record is held, and the network identifier that is included in the received negotiation response packet and represents the network to which the redirect destination belongs is referred to as “redirect destination network identifier”. Store it in the record of the redirect table;
The first redirect device searches the redirect table when a packet is received from an external network, and further receives a packet in addition to the search condition and the matching condition described in any one of claims 1 to 3. When the external network has a record that matches the “redirect destination network identifier” of the record, the conversion processing shown in any one of claims 1 to 3 is performed, and the packet is transferred to the first communication device. Redirection method characterized by One device that is physically or logically connected to the external network, has a first address assigned from the connected external network, and has a second address for connecting to the inside is connected. After the first communication device transmits a connection request packet to the external network in order to start communication via the external network, the negotiation request packet is transmitted to the other device using the reception of the connection request packet as a trigger. When the other apparatus receives the negotiation request packet, the other apparatus writes a negotiation with a new connection destination, that is, a redirect destination second communication apparatus in order to give a connection destination change instruction, that is, a redirect instruction. A response packet is transmitted to the one device, and the one device transmits the negotiation response packet. The first redirect device recognizes the redirect destination from the redirect destination address included in the received negotiation response packet, and the first redirect device thereafter transmits the destination address among the packets received from the first communication device. Communication between the first communication device and the second communication device by converting the packet whose address is the address of the other device to the external network by converting the destination address included in the packet to the redirect destination address In a redirect device that enables
“Redirect source address” and “redirect destination address” are used as records, and when the negotiation response packet is received as a trigger, the destination address of the negotiation request packet is set as “redirect source address” and the negotiation is performed. A redirect table that stores the address of the communication device of the redirect destination included in the response packet in addition to the record as a “redirect destination address”;
When one device receives a packet from an external network, the redirect table is searched, and if there is the record in which the source address of the received packet matches the “redirect destination address”, A redirection apparatus comprising: a conversion means for converting a transmission source address into a “redirection source address” of the matched record. The redirect device according to claim 7,
If the address of the communication device cannot be used in an external network, a “source address” is added to the elements constituting the record, and the source address of the connection request packet that triggered the transmission of the negotiation request packet is set. As the “source address”, the reception of the negotiation response packet is used as a trigger, the transmission destination address of the negotiation request packet is set as the “redirect source address”, and the redirect destination communication device included in the negotiation response packet A redirect table that stores the address as a “redirect address” in the record;
When a packet is received from an external network, the redirect table is searched, and when there is the record whose “redirect destination address” matches the source address of the received packet, the destination address of the received packet is A redirection apparatus comprising: conversion means for converting to a “transmission source address” of a matched record, and further converting a transmission source address to a “redirection source address” of the matched record. The redirect device according to claim 7 or 8,
In order to enable direct communication with the redirect destination and to correctly recognize that the communication is from the redirect destination, the elements constituting the record of the redirect table include an “application identifier” and a “session identifier”. One or both of them is added, and an identifier indicating the type of application included in the connection request packet that is a transmission trigger of the negotiation request packet is “application identifier”, and an identifier indicating the session is “session identifier” A redirect table stored in the record of the redirect table;
When one device receives a packet from an external network, the one device searches the redirect table, and in addition to the search condition and the matching condition according to claim 7 or 8, an identifier representing an application type of the received packet And a conversion means for performing the conversion process according to claim 7 or 8 when there is a record in which an identifier representing a session matches an “application identifier” and a “session identifier” of the record. Redirect device to do. The redirect device according to claim 7 or 8,
When the one device is connected to a plurality of networks, a “redirection destination network identifier” is added to an element constituting the record of the redirect table according to claim 7, and the received negotiation response is received. A redirect table that is included in the packet and stores the network identifier representing the network to which the redirect destination belongs in the record as a “redirect destination network identifier”;
The one device searches the redirect table when receiving a packet from an external network, and in addition to the search condition and the matching condition according to any one of claims 7 to 9, the external network further receiving the packet 10. A redirection apparatus comprising: a conversion unit that performs conversion processing according to claim 7 when there is a record that matches a “redirect destination network identifier” of the record.   A procedure for transmitting a negotiation request packet to the second redirect device, triggered by reception of a connection request packet from the first communication device, to the computer of the first redirect device, and the negotiation response packet A procedure for receiving, a procedure for recognizing the redirect destination from the redirect destination address included in the received negotiation response packet, and thereafter, the destination address of the packet received from the first communication device is the second redirect device A procedure for converting a packet that is an address into a redirect destination address included in the packet, a procedure for transmitting the packet to an external network, and a redirect table with “redirect source address” and “redirect destination address” as records. Search procedure, Nego Triggered by the reception of the station response packet, the destination address of the negotiation request packet is set as the “redirect source address”, and the address of the redirect destination communication device included in the negotiation response packet is set as the “redirect destination address”. Stored in the record of the redirect table, when a packet is received from an external network, the redirect table is searched and there is a record in which the source address of the received packet matches the “redirect destination address”. For performing a conversion process for converting the transmission source address of the received packet into the “redirection source address” of the matched record, and a procedure for transferring the packet to the first communication device. For professional Lamb. The redirection program according to claim 11,
If the address of the communication device 1 is not available on the external network to the computer of the first redirect device, a procedure for adding a “source address” to the elements constituting the record of the redirect table, The transmission source address of the connection request packet that became the transmission trigger is set as a “transmission source address”, the reception of the negotiation response packet is set as a trigger, the transmission destination address of the negotiation request packet is set as the “redirection source address”, Procedure for storing the address of the communication device of the redirect destination included in the negotiation response packet as the “redirect destination address” in the record of the redirect table, and detecting the redirect table when the packet is received from the external network. A procedure for converting the transmission destination address of the received packet to the “transmission source address” of the matched record when there is the record whose “redirection destination address” matches the transmission source address of the received packet; Furthermore, a redirection program for executing a procedure for performing a conversion process for converting a transmission source address into a “redirection source address” of the matched record and a procedure for transferring a packet to the first communication device. The redirection program according to claim 11 or 12,
A step of adding one or both of an “application identifier” and a “session identifier” to an element constituting the record of the redirect table to a computer of the first redirect device; a transmission request for a negotiation request packet; The procedure for storing in the record of the redirect table with the identifier indicating the type of application included in the connection request packet as “application identifier” and the identifier indicating the session as “session identifier”, the packet received from the external network In addition to the procedure for searching the redirect table, the search condition and the matching condition according to claim 11 or 12, the identifier indicating the application type of the received packet and the identifier indicating the session are When there is a record that matches the “application identifier” and “session identifier” of the code, the procedure for performing the conversion process according to claim 11 or 12 and the procedure for transferring the packet to the first communication device are executed. Redirect program to make it happen. The redirection program according to claim 11 or 12,
When the external network is an IP network in the computer of the first redirect device, the communication protocol is Internet Protocol, and the redirect source address, redirect destination address, and source address that constitute the record of the redirect table are IP addresses. The destination IP address included in the connection request packet that is configured and used as the transmission trigger of the negotiation request packet or the redirect source address indicated in the negotiation response packet is indicated in the “redirect source address” and the negotiation response packet. A redirect destination address to be stored as a “redirect destination address” in the record of the redirect table, when a packet is received from an external network Retrieval table search procedure, if the source IP address of the received packet matches the “redirect destination address”, the source IP address is converted to the “redirect source address” of the matched record And a conversion process for converting the destination IP address of the received packet into the “source address” of the matched record, and forwarding the packet to the first communication device. Redirection program to execute each procedure to execute. The redirection program according to claim 11 or 12,
In order to enable direct communication with the redirect destination when TCP or UDP is used for the computer of the first redirect device, in addition to the configuration of the record of the redirect table according to claim 14, The procedure for adding two elements of "IP protocol number" and "source port number" that enable identification of TCP and UDP, respectively, as the "application identifier" and "session identifier" described in claim 14, In addition to storing the redirect table in the record, the protocol number of the IP header included in the connection request packet that triggered the transmission of the negotiation request packet is “application identifier”. In the case of TCP or UDP, TCP or UDP Source port number included in the header 13 as a “session identifier”, a procedure for storing the packet in the record of the redirect table, a procedure for searching the redirect table for a packet received from an external network, The procedure for performing the conversion processing according to claim 14 when there is a record in which the protocol number of the IP header matches the “application identifier” and the destination port number matches the “session identifier”, and the packet is sent to the first communication device. Redirect program to execute each transfer procedure. The redirection program according to claim 11 or 12,
14. In the case where the computer of the first redirect device is connected to a plurality of networks, a “redirect destination network identifier” is set in an element constituting the record of the redirect table according to any one of claims 11 to 13. A procedure for adding, a procedure for storing a network identifier representing a network to which a redirect destination belongs in a received negotiation response packet as a “redirect destination network identifier” in the record of the redirect table, a packet received from an external network 14. In addition to the procedure for searching the redirect table at the time, the search condition and the matching condition according to any one of claims 11 to 13, the external network that has received the packet further transmits the “redirect destination network identifier” of the record. If a match record, the procedure for performing a conversion process according to any one of claims 11 to 13, the procedure for transferring a packet to the first communication device, the redirect program instructs respectively.   A computer-readable recording medium in which the redirect program according to any one of claims 11 to 16 is recorded.

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