JP4269343B2 - Name resolution server and packet transfer device - Google Patents

Description

  The present invention relates to a name resolution server and a packet transfer apparatus, and more particularly to a name resolution server and a packet transfer apparatus that can customize a name resolution response based on attribute information of a sender of a name resolution request message.

  Conventionally, a DNS (Domain Name System) server is known as this type of name resolution server. This DNS server is mainly used for name resolution from an FQDN (Fully Qualified Domain Name) to an IP address or from an IP address to an FQDN as shown in RFC1034, for example, in an IP (Internet Protocol) network. . A client requesting name resolution transmits a DNS query message, which is a name resolution request message, to the DNS server, makes a request for name resolution, and receives a DNS response message as a name resolution response from the DNS server.

  A general DNS server is based on always returning the same resolution result (IP address, FQDN, etc.) when inquiring about the same name (FQDN, IP address, etc.). However, in recent years, there are increasing cases of using a DNS server having an additional function of returning different name resolution results depending on the situation even when inquiring about the same name. Hereinafter, specific examples of the additional function will be given.

  First, a function called View of BIND (Berkeley Internet Name Domain), which is widely used as DNS server software, is mentioned. By using View, even if the DNS server is inquired about the same name, the resolution result returned to the client can be changed depending on the source IP address of the DNS query message or the FQDN or IP address inquired by the DNS query message.

  For example, when the source IP address of the DNS query message is a private address, FQDN: www. aaa. When the source IP address of the DNS query message is a global IP address, FQDN: www. aaa. The IP address of the web server installed in the extranet is returned in response to the inquiry about the com.

  In addition, in a CDN (Content Delivery Network), the additional function of the DNS server may be used for load distribution of the content distribution server and improvement of user performance. In the CDN, for the purpose of distributing load between servers and improving user performance, it is generally performed that a single content is arranged on a plurality of servers and requests from each user are distributed to an appropriate server. Here, the DNS server is used when selecting a server that transmits a user request.

  In the DNS server, when the IP address of a plurality of content distribution servers having the same content is registered for one FQDN and the client makes an inquiry to the FQDN, the DNS server determines the server load and the user. The IP address of the content distribution server that is optimal from the viewpoint of performance is returned to the client. Here, the source IP address of a DNS query message transmitted by a client or a local DNS server (a DNS server that receives a DNS query message from a client and takes over name resolution processing) is generally used as information about the client.

  Furthermore, in Japanese Patent Laid-Open No. 2001-273225 (hereinafter referred to as Patent Document 1), the DNS server not only includes the load status and location information of the content distribution server, but also the client information, not only the source IP address of the DNS query message The location information (latitude, lightness, etc.) is also obtained, and in response to the DNS query from the client, the optimum server for the client is selected based on this information, and the IP address of that server is returned. ing.

  In order to allow the DNS server to acquire the client location information, the client resolver embeds the client location information in a DNS query message and sends it to the DNS server. The DNS server can acquire the location information of the client by receiving the DNS query message including the location information.

JP 2001-273225 A

  The first problem of the prior art is that the DNS server cannot customize name resolution based on various attribute information of the user who sent the DNS query message. Even if customization is possible, it is necessary to embed various attribute information of the user who sent the query message in the DNS query message. Therefore, it is necessary to change the resolver on the client or the node that performs the DNS query. Become.

  By the way, each user who requests name resolution has very various attributes such as location, preference, connection status to a use terminal and a network, and these attributes are different for each user. The name resolution customization is to change the name resolution result to be responded according to the attribute of the user who requested the name resolution in consideration of different attributes for each user. As an example of name resolution customization, when resolving the IP address corresponding to the FQDN of the server that distributes the video, even if the DNS query is for the same FQDN, for example, a user whose connection line type is an ADSL line In some cases, the IP address of a server that distributes in a wide band is resolved, or the IP address of a server that distributes in a narrow band is resolved for a user whose connection line type is an ISDN line. Can be mentioned. Furthermore, name resolution can be customized by performing name resolution in consideration of more user attribute information such as a user's position, preference, and use terminal.

  However, conventional DNS servers can only customize name resolution based on the data embedded in the DNS query message. In a general DNS, the DNS query message includes only the source IP address of the DNS query message as information about the user. For this reason, a general DNS server cannot acquire information other than the source IP address of the DNS query message regarding the user. Also in the BIND View function described above, the DNS server can only consider the source IP address of the DNS query message when resolving the name.

  Further, in the conventional technology, when name resolution is customized using information other than the source IP address of the DNS query message, it is necessary to embed all necessary information in the DNS query message.

  Japanese Patent Application Laid-Open No. 2004-151561 describes a method of embedding user location information in a DNS query message transmitted by a client in order to perform name resolution based on the user location information in a DNS server. However, this method has problems in two respects. First, in order to embed information necessary for customizing name resolution in a DNS query message, the user environment such as an OS and application software used by the user must be changed.

  Resolvers that have become popular nowadays have no function of grasping user attribute information and embedding it in a DNS query message, so it is necessary to change the resolver, but to change the resolver for all users who use the DNS server Is a big cost.

  Further, the second point is that even if the resolver is changed and the user attribute information is embedded in the DNS query message, the type of user attribute information to be embedded is fixed, so the user attribute information required by the DNS server is However, it is not possible to cope with the case where the value differs depending on each DNS server. As described above, it is difficult to obtain user attribute information necessary for the DNS server to customize name resolution by the conventional technique.

  The second problem of the prior art is that the information (such as the IP address for FQDN) included in the DNS response message sent from the DNS server to the client is a packet installed on the route between the DNS server and the client. The transfer device cannot be used.

  For example, consider connecting a client to a website. In order to connect to the Web site, the client first resolves the IP address for the FQDN of the Web site by DNS, and connects to the IP address obtained as a result of the resolution. In the control related to the connection between the client and the Web site, the DNS server only teaches the client the IP address of the Web site, that is, only controls the connection destination.

  In addition to the control related to the connection between the client and the website, control of packet transfer methods such as how to transfer packets passing over the connection (header rewriting, outgoing route control, priority transfer control, etc.) However, the control of these packet transfer methods is not statically set by the client but statically or dynamically by a routing protocol or the like on the packet transfer device installed on the passage route between the client and the website. Therefore, the DNS server cannot control these packet transfer methods.

  Here, the packet transfer device refers to all devices that perform packet transfer processing, such as an Ethernet (registered trademark) switch, an ATM (Asynchronous Transfer Mode) switch, a router, a layer 4 switch, and a layer 7 switch.

  If both the control of the connection destination in the client and the control of the transfer method in the packet transfer apparatus can be performed simultaneously by the DNS server, it can be said that the two controls are effective in cooperation. For example, in the connection between a previous client and a Web site, the connection destination of the client is the Web server with the lowest load, and a packet passing over the connection between the client and the Web server in the middle packet transfer device If the control for preferential transfer is simultaneously performed by the DNS server, it is possible to effectively realize the high-speed access between the client and the Web site.

  However, at present, the control of the connection destination in the client and the control of the transfer method in the packet transfer apparatus are separated. From the standpoint of the packet transfer apparatus, the information contained in the DNS response message sent from the DNS server to the client cannot be used, and from the standpoint of the DNS server, the DNS response message sent to the client. Therefore, the transfer method in the packet transfer apparatus cannot be controlled.

  The first object of the present invention is to provide user attribute information necessary for the name resolution server to customize name resolution without forcing changes to the current user environment (terminal, OS, application software, etc. used by the user). It is an object of the present invention to provide a name resolution server that can acquire and finely customize name resolution based on the acquired user attribute information.

  The second object of the present invention is to provide user attribute information necessary for the name resolution server to customize name resolution without forcing changes to the current user environment (terminal, OS, application software, etc. used by the user). It is to provide a name resolution server that has a function of dynamically acquiring and managing user attribute information dynamically as well as finely customizing name resolution based on the acquired user attribute information.

  A third object of the present invention is to provide a name resolution server capable of controlling both a connection destination in a client and a packet transfer method in a packet transfer apparatus.

  A fourth object of the present invention is to provide a packet transfer apparatus in which a packet transfer method can be controlled by a name resolution message exchanged between a client and a name resolution server.

  The present invention according to claim 1 performs name resolution on the received name resolution request message and a packet forwarding apparatus having a function of forwarding the received packet to another node, and results of the name resolution by a name resolution response message A name resolution system including a name resolution server that returns a name resolution request message transmitted from a client to the name resolution server. The name resolution request message is temporarily received by the packet forwarding device, and the name forwarding request is received by the packet forwarding device. Attribute information about the user who is the sender of the message is acquired based on a source address included in the name resolution request message, and after the attribute information is added to the name resolution request message, the name resolution request message is added to the name resolution request message. Sent to the name resolution server, the name resolution server Based on the attribute information included in the name resolution request transmitted by the packet transfer device, a name resolution response message that is a result of the name resolution is returned, and the name resolution response message is transmitted through the packet transfer device. It is returned to the client.

  In the name resolution system of the present invention of claim 2, the packet transfer device includes a user information database in which the attribute information is stored as an internal element, and attribute information about a user who is a sender of the name resolution request message. Obtained from the user information database.

  The name resolution system according to a third aspect of the present invention is characterized in that the packet transfer apparatus acquires the attribute information from an external database server including a user information database in which the attribute information is stored.

  The name resolution system of the present invention of claim 4 is characterized in that the packet transfer apparatus uses a name resolution request message in acquiring the attribute information from the external database server.

  The name resolution system of the present invention according to claim 5 is characterized in that the external database server is a name resolution server installed outside.

  In the name resolution system of the present invention according to claim 6, the packet forwarding apparatus is based on a user authentication unit for identifying and authenticating a user in a client connected to the node, and attribute information about the user obtained at the time of authentication. And a user information update unit for updating the contents of the user information database.

  The present invention of claim 7 is a name resolution method in which a name resolution server performs name resolution on a name resolution request message sent by a client and returns the result of the name resolution by a name resolution response message. The name resolution request message transmitted from the client to the name resolution server is temporarily received by a packet forwarding apparatus that exists between the client and the name resolution server and has a function of forwarding a received packet to another node, Attribute information about the user who is the sender of the name resolution request message is acquired by the packet transfer device based on a source address included in the name resolution request message, and the attribute information is added to the name resolution request message. After the name resolution request message is sent to the name resolution server And the name resolution server returns a name resolution response message as a result of the name resolution based on the attribute information included in the name resolution request transmitted by the packet transfer apparatus, and the name resolution response message Is returned to the client via the packet transfer device.

  The first name resolution server of the present invention acquires attribute information of the user who transmitted the name resolution request message by referring to the user information database in which the attribute information of the user who transmitted the name resolution request message is registered. A user information acquisition unit and a response creation unit that finely customizes name resolution based on the acquired attribute information. By adopting such a configuration, the first name resolution server of the present invention can customize name resolution using the attribute information of the message sender that is not included in the received name resolution request message. The client does not need to include in the message the attribute information that the name resolution server needs to customize name resolution. That is, name resolution based on various attribute information can be customized in the name resolution server without changing the current user environment (terminal, OS, application software, etc. used by the user). Therefore, the first object of the present invention can be achieved.

  The second name resolution server of the present invention includes a user information management unit in addition to the configuration of the first name resolution server of the present invention. The user information management unit stores the attribute information and login status information collected by the authentication server from the authentication server, and further stores the acquired attribute information and login status information in the user information database. A user information management unit that dynamically registers attribute information or dynamically deletes attribute information from a user information database. By adopting such a configuration and automatically registering or deleting attribute information referred to in name resolution in the user information database, the second object of the present invention can be achieved.

  The third name resolution server of the present invention refers to the response database in which both the connection destination corresponding to the name and the packet transfer method to the connection destination are registered, and the name inquired by the name resolution request message A response creation unit that creates a name resolution response message including both the connection destination corresponding to the packet and the packet transfer method to the connection destination. When such a configuration is adopted and a name resolution request message is received, a name resolution response message including a connection destination corresponding to the inquired name and a packet transfer method to the connection destination is transmitted to the client. The packet transfer apparatus of the invention can use the packet transfer method included in the name resolution response message. Therefore, the third object of the present invention can be achieved.

  The packet transfer apparatus of the present invention includes a user information acquisition unit that acquires attribute information of a user who has transmitted a name resolution request message, and embedding the attribute information acquired by the user information acquisition unit in the name resolution request message. And a DNS proxy unit that extracts the packet transfer method from the name resolution response message transmitted by the name resolution server 2 and stores it in the routing table. When such a configuration is adopted and a packet is transferred, the packet transfer method extracted from the name resolution response message transmitted by the second name resolution server of the present invention is referred to, so that the fourth Aim can be achieved.

  The first effect is that the name resolution response in the name resolution server can be flexibly customized based on arbitrary attribute information of the sender (user) of the name resolution request message without changing the resolver in the client.

  The reason is that the first name resolution server of the present invention holds a user information database in which user attribute information is stored, and considers the user attribute information by referring to the database when receiving the name resolution request message. This is because the name resolution process can be customized.

  The second effect is that the name resolution server can automatically create and manage a database including user attribute information related to the sender of the name resolution request message used to customize the name resolution response.

  The reason is that the second name resolution server of the present invention cooperates with the authentication server, dynamically acquires the user attribute information from the authentication server, and automatically registers and deletes the user attribute information from the database. It is because it can be performed.

  The third effect is that the information included in the name resolution response message sent from the name resolution server to the client can be used not only by the client but also by a packet transfer apparatus installed between the client and the DNS server. become.

  The reason is that when the name resolution server of the present invention transmits a name resolution response message to the client, the packet transfer method in the packet transfer apparatus of the present invention corresponding to the response is embedded together with the normal name resolution response. Further, the packet transfer apparatus of the present invention receives the response message once before the response message reaches the client, extracts the packet transfer method embedded in the response message, and stores it in the routing table in its own node. This is because a corresponding entry is created.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
Referring to FIG. 1, the first embodiment of the present invention is realized by a client A1 and a DNS server B1 which is a name resolution server. The client A1 and the DNS server B1 are connected via the network C1. The DNS server B1 can be generalized not only as a server having a name resolution function in DNS but also as a server having a name resolution function in other applications. Examples of a server having a name resolution function in other applications include a WINS (Windows (registered trademark) Internet Name Service) server and a NIS (Network Information Service) server. However, a DNS server will be described as an example of a server having a name resolution function below.

  The client A1 resolves the IP address corresponding to the FQDN of the node on the network, such as “www.biglobe.ne.jp” or “ftp.nec.com”, or the FQDN corresponding to the IP address in the opposite direction. In order to resolve this, a DNS query message is transmitted as a name resolution request message to the DNS server B1. Other examples of the purpose of the client A1 using the DNS server B1 include resolution of a host and a port number that provide the service corresponding to a service name such as ftp or http as described in RFC2782. As described in RFC 2916, a URI (Universal Resource Identifier) corresponding to a telephone number can be used. However, the following description will focus on the case where the DNS server B1 resolves the IP address from the FQDN or resolves the FQDN from the IP address.

  In response to the transmitted DNS query message, the client A1 receives the DNS response message as a name resolution response message returned from the DNS server B1. The DNS response message includes the result of name resolution.

  An example of the client A1 is generally a terminal node (use terminal) such as a PC (Personal Computer), a portable terminal, or a workstation. In addition, another DNS server other than the DNS server B1 has some name resolution. In some cases, a recursive DNS query is performed on the DNS server B1 in order to perform the above, and such a DNS server can be included in the client A1.

  The DNS server B1 includes a query reception unit B11, a user information identification unit B12, a user information acquisition unit B13, a user information database B14, a response creation unit B15, a response database B16, and a response transmission unit B17. .

  The DNS server B1 is significantly different from the conventional DNS server in that it includes a user information identification unit 12, a user information acquisition unit B13, and a user information database B14.

  The query receiving unit B11 receives the DNS query message transmitted by the client A1, and passes it to the user information identifying unit B12.

  Upon receiving the DNS query message, the user information identification unit B12 checks whether the user attribute information of the user who is the sender of the message is included in the message, and if it is included, displays the user attribute information. Read and identify. If not included, a process is performed for acquiring user attribute information of the sender of the DNS query message from the user information database B14 via the user information acquisition unit B13.

  In addition, when the user attribute identification unit B12 can acquire the user attribute information, the user information identification unit B12 passes the user attribute information and the DNS query message to the response creation unit B15. When the user attribute information cannot be acquired, only the DNS query message is passed to the response creation unit B15.

  Here, the user attribute information is, for example, the user ID of the user (client A1), location information, information on preferences such as hobbies or behavior history, the type of terminal used such as a mobile phone, PDA (Personal Digital Assistants), and a notebook computer. OS (Operating System) installed in the terminal, installed network interface, CPU speed, information on the used terminal such as the amount of memory, IP address and MAC address of the used terminal, ADSL (Asymmetric Digital Subscriber Line) and ISDN (Integrated) Service line type (Services Digital Network), connection line speed, connected NAS (N Such as information about the connection status to twork Access Server) IP address, such as network, refer to the information in general about the user.

  When the user attribute information of the sender of the message is not included in the DNS query message received by the DNS server B1, the user information acquisition unit B13 receives the information passed from the user information identification unit B12 (the source of the message The user attribute information is acquired from the user information database B14 based on the IP address or the source MAC address, etc., and passed to the user information identification unit B12.

  In the user information database B14, user attribute information of a user who performs name resolution with respect to the DNS server B1 and a reference destination for acquiring the user attribute information are registered. Arbitrary user attribute information can be registered in the user information database B14 as necessary.

  An example of the contents of the user information database B14 is shown in FIG. In the user information database B14 of FIG. 2, the login ID to the network operated by the ISP (Internet Service Provider), the IP address of the terminal used, the type of connection line, the IP address of the connected NAS, and the user information database B14 When necessary user attribute information can be acquired from an external server although not directly registered, a reference destination for acquiring the user attribute information is registered.

  In FIG. 2, “-” indicates that the content of the corresponding item is not registered in the user information database B14. For example, in the first entry, the reference destination is “-”, and for a user whose attribute information is registered in this entry, it indicates that the reference destination for obtaining more attribute information is unknown or does not exist. Yes. The second entry indicates that the connection line type is unknown, and the user attribute information that is not registered is designated by the IP address “8.9.1.4” registered in the reference destination. It is shown that it can be obtained by referring to the node to be executed. Furthermore, in the third entry, the user attribute information whose IP address of the using terminal is in the range of “123.45.1.0/24” is specified, and the node whose IP address is specified by “9.9.9.9” It is shown that it can be obtained by referring to.

  The response creation unit B15 refers to the response database B16 and performs name resolution processing such as FQDN → IP address or IP address → FQDN requested by the DNS query message. Here, when the user attribute information is transferred together with the DNS query message from the user information identification unit B12, the name resolution process considering the user attribute information is performed. By considering the user attribute information, for example, when the user requests the name resolution of the FQDN → IP address of the server that distributes the video, even if the DNS query is related to the same FQDN, for example, the connection line type is ADSL For users who are on the line, resolve the IP address of the server that distributes in a wide band, or for users whose connection line type is an ISDN line, resolve the IP address of the server that distributes in a narrow band It is possible to customize name resolution processing for each user.

  In the response database B16, entries indicating solutions such as FQDN → IP address and IP address → FQDN are registered for each user attribute. A default name resolution method that does not depend on user attribute information is also registered.

  An example of the response database B16 is shown in FIG. The response database B16 shown in FIG. 3 includes two types of tables. One is a table (zone file) in which specific name resolution methods such as FQDN → IP address are registered, and zone files 202 and 203 correspond thereto. The main information registered in the zone files 202 and 203 includes TYPE indicating the type of entry, FQDN as a key for name resolution, and DATA indicating data responding by name resolution. Examples of TYPE used include an A record indicating resolution of an IP address corresponding to a certain FQDN, an MX record indicating resolution of a mail server address corresponding to a certain FQDN, and a CNAME record indicating an alias of a certain FQDN. Here, referring to the first entry of the zone file 202, the entry type (TYPE) is an A record indicating the resolution of the IP address from the FQDN, and the FQDN: www. aaa. It is shown that the IP address (DATA) corresponding to “com” is “9.8.7.6”.

  The other is a table (name resolution table) in which reference destinations of name resolution methods are registered for each user attribute information and domain space, and corresponds to the name resolution table 201. In the name resolution table 201, reference destinations of name resolution methods are registered for each combination of user attribute information such as user IP address, user ID, connection line type, and NAS IP address.

  In the name resolution table 201, “-” indicates user attribute information that is not considered in name resolution. For example, in the first entry, the user IP address and the user ID are not considered in the user attribute information, but only the connection line type and the NAS address are considered. The first entry is for a user whose user IP address and user ID are arbitrary, the connection line type is an ADSL line, and the IP address of the connected NAS is “30.30.30.30”. , Domain space aaa. When the FQDN belonging to the FQDN is inquired, the zone file adsl_aaa_com. dat (zone file 202) is referred to. Similarly, in the third entry, the user IP address, the access line type, and the NAS IP address are arbitrary in the user attribute information, and the user whose user ID is “jiro” is the domain space bbb. When the FQDN belonging to the FQDN is inquired, the zone file jiro_bbb_com. dat is referred to. The fourth entry includes an IP address “123.45.1.5” and a domain space bbb. When there is a DNS query of FQDN belonging to “com”, it indicates that name resolution processing is performed in another DNS server specified by the IP address “1.2.3.4”.

  In the last entry (DEFAULT), a default IP address resolution method that does not depend on user attribute information is registered. This entry is when the user attribute information does not correspond to any of the user attribute information registered in the name resolution table 201, or when the user attribute information corresponding to the DNS query message cannot be acquired in the user information identification unit B12 To be referenced.

  The response transmission unit B17 generates a DNS response message based on the name resolution processing result passed from the response creation unit B15, and transmits the DNS response message to the client A1.

  Next, with reference to FIG. 4, in this Embodiment, the operation | movement until it transmits a response message after the DNS server B1 receives a DNS query message is demonstrated in detail.

  When receiving a DNS query message from the client A1 (step S101 in FIG. 4), the query receiving unit B11 passes the message to the user information identifying unit B12.

  When receiving the DNS query message, the user information identification unit B12 performs a process of acquiring user attribute information of the sender of the message (step S102).

  Here, the user attribute information acquisition process in step S102 will be described in detail with reference to FIG.

  First, the user information identification unit B12 determines whether user attribute information is embedded in the received DNS query message (step S1021 in FIG. 5). If the user attribute information is embedded, it is read out and acquired (step S1022), and the user attribute information acquisition process ends.

  If the user attribute information is not embedded in step S1021, the received DNS query message is passed from the user information identification unit B12 to the user information acquisition unit B13, and the user information acquisition unit B13 identifies the user who transmitted the message. Information serving as a clue is extracted (step S1023). As an example of information to be extracted, a source IP address of a DNS query message can be given. This is because when the client A1 is the resolver of the user using terminal, the source IP address of the DNS query message is the IP address of the user using terminal. In addition, when the client A1 is a resolver of a user terminal and the client A1 and the DNS server B1 are directly connected without a router in the middle, the source MAC address of the client A1 is also the same as the user who transmitted the DNS query message. It can be used as a clue to specify.

  Next, the user information acquisition unit B13 searches for an entry corresponding to the information extracted in step S1023 from the user information database B14 (step S1024).

  If there is no corresponding entry in step S1024, the acquisition process in step S103 ends (step S1025).

  If there is a corresponding entry in step S1024, should the user information acquisition unit B13 acquire user attribute information with reference to an information source other than the local user information database B14 based on the contents of the corresponding entry? It is determined whether or not (steps S1025 and S1026). If it is determined that the user attribute information need not be acquired with reference to another information source other than the local user information database B14, the user information acquisition unit B13 acquires the user attribute information from the entry found in step S1025. (Step S1027).

  When it is determined that the user attribute information should be acquired with reference to other information sources, the user information acquisition unit B13 acquires user attribute information from the entry found in step S1025, and further includes the user information database B14. User attribute information acquisition processing is performed with reference to other information sources. (Step S1028).

  In the above, whether or not to acquire by referring to information sources other than the local user information database B14 is determined by whether or not a reference destination such as an external server is registered in the user information database B14.

  For example, an example of steps S1025 to S1028 when the user information database B14 has the contents shown in FIG. 2 will be described. When the source IP address is extracted from the DNS query message as information for identifying the user, and the IP address is “123.45.0.2”, the user information acquisition unit B13 reads from the user information database B14. An entry whose IP address is “123.45.0.2” is searched (step S1025). In this case, the found entry is the first entry, and the reference destination is “-”. Therefore, the user information acquisition unit B13 does not refer to other nodes (external servers, etc.), and the user information Judgment is made by referring only to the database B14 (step S1026), and the user attribute information indicated in the first entry is obtained (step S1027).

  If the source IP address of the DNS query message is “123.45.0.4”, the second entry is found. Since the IP address of the reference destination node is registered in the reference destination, the user information acquisition unit B13 determines that another node should be referred to (step S1026) and is registered in the second entry. The user attribute information is also acquired from the database of user attribute information held by the node of the registered IP address (step S1028).

  Returning to the flowchart of FIG. After the user attribute information acquisition process in step S102, the user information identification unit B12 passes the DNS query message received by the DNS server B1 and the user attribute information of the message sender together to the response creation unit B15. If the user attribute information of the message sender cannot be acquired in step S102, the message is handled as having no corresponding user attribute information, and only the DNS query message is passed to the response creation unit B15.

  When the response creation unit B15 is passed together with the DNS query message and the corresponding user attribute information, the response creation unit B15 displays the FQDN or IP address inquired in the DNS query message and the entry corresponding to the user attribute information in the response database B16. Search by referring to (step S103). When only the DNS query message is received, a default entry corresponding to the FQDN or IP address inquired by the received DNS query message is searched with reference to the response database B16 (step S103).

  The response creation unit B15 determines whether name resolution should be performed by another DNS server from the contents of the retrieved entry (step S104). Here, when the address of another DNS server is registered as a reference destination of the name resolution table 201 of the response database B16 shown in FIG. 3, it is determined that the name resolution should be performed by the other DNS server.

  In step S104, when it is determined that it should be performed by another DNS server, the name resolution process is performed by another DNS server (step S106). The following two methods can be given as examples of a method for performing the name resolution processing so that it is performed by another DNS server.

  The first method is a method of transferring both the user attribute information passed from the user information identifying unit B12 and the DNS query message or only the DNS query message to another DNS server. FIG. 6 shows the configuration of the response creation unit B15 when this method is adopted.

  Referring to FIG. 6, the response creation unit B15 includes a response creation main unit B151 and a resolver unit B152. When the response generation main unit B151 performs the processing of steps S103 and S104 described above and determines in step S104 that name resolution should be performed by another DNS server, the response generation main unit B151 identifies the user information to the resolver unit B152. Both the user attribute information passed from the part B12 and the DNS query message or only the DNS query message are passed, and other DNS servers to be subjected to name resolution are notified. The resolver unit B152 transfers both the user attribute information and the DNS query message or only the DNS query message based on the information passed from the response creation main unit B151.

  As a method for the resolver unit B152 to transfer both the user attribute information and the DNS query message to another DNS server, for example, a DNS query message is constructed according to the DNS message format, and the user attribute information is embedded in the DNS message and transmitted. Can be considered. In the DNS message format, a field called an additional information section is prepared for embedding additional information. Arbitrary information can be embedded in the DNS resource record format in the additional information section.

  In this method, the received user attribute information is encoded into a resource record format, embedded in the additional information part of the DNS query message, and transferred to another DNS server (step S106). When the resolver unit B152 receives the corresponding DNS response message from the other DNS server that has transferred the DNS query message, the resolver unit B152 passes it to the response transmission unit B17, and the response transmission unit B17 transfers the response message to the client A1. (Step S107).

  By using this transfer method, it is possible to process a DNS query message in which user attribute information is embedded in a conventional DNS server, so that the DNS server B1 according to the present invention and other conventional DNS servers coexist. Can be achieved.

  In the second method, a message notifying client A1 that name resolution should be performed by another DNS server is returned as a DNS response message, and client A1 receiving the notification again sends a DNS query message to another DNS server. How to send. In this case, the response transmission unit B17 transmits to the client A1 a DNS response message including the IP address of another DNS server to which the client A1 should transmit a DNS query message again (step S107).

  On the other hand, in step S104, if the response creation unit B15 determines that the name resolution should be performed in its own server, the name resolution of FQDN → IP address or IP address → FQDN is performed according to the contents of the searched entry ( Step S105), and the result is passed to the response transmitter B17.

  The response transmission unit B17 generates a DNS response message based on the received name resolution result, and transmits it to the client A1 (step S107).

  In the above description of the first embodiment, the DNS server B1 includes the user information database B14 as its component. As another configuration, a mode in which the user information database B14 is held not in the DNS server B1 but in another server is also conceivable. The configuration in this case is shown in FIG. 7 as another example of the first embodiment.

  In this other example, a DNS server B2 that does not include the user information database B14 is used in place of the DNS server B1 shown above, compared to the configuration shown in FIG. A database server D1 included as an element is used.

  The operation of the DNS server B2 in the configuration shown in FIG. 7 can be similarly considered by replacing the user information database B14 with the user information database D11 in the above-described operation of the DNS server B1.

  The function of the database server D1 can be realized by a dedicated node, or can be realized as a function of another DNS server B1 or B2. In the latter case, the user information database D11 is managed as a response database B16, and the user information acquisition unit B13 acquires user attribute information from the other DNS server B1 or B2 using a DNS message.

  An example of the contents of the response database B16 in this case is shown in FIG. The name resolution table 301 shown in FIG. 8 has the same format as the name resolution table 201 shown in FIG. 3, and the user attribute information is acquired by referring to the third entry. The third entry has user attribute information of the file user_com. It is stored in dat (zone file 302). The zone file 302 stores the same user attribute information as the user information database B14 shown in FIG. 2, and the user attribute information is a kind of DNS resource record using the FQDN including the IP address of the user's terminal as a key. Is stored in the form of a TXT record.

  For example, from the first entry of the zone file 302, the login ID is taro (login id = taro) as the user attribute information of the user whose use terminal IP address is “123.45.0.2”, the connection line It can be seen that the type is an ADSL line (access media = ADSL) and the IP address of the connected NAS is “30.30.30.30” (NAS address = 30.30.30.30). When the user information acquisition unit B13 wants to acquire user attribute information of the user whose IP address of the use terminal is “123.45.0.2”, the domain name is “123.45.0” for the database server D1. .2.user.com "sends a DNS query message requesting a TXT record.

  Next, the effect of the first embodiment will be described.

  In the present embodiment, the DNS server B1 refers to the user information database B14 in which user attribute information is managed, thereby customizing the name resolution process considering the user attribute information. If user attribute information is registered in the user information database B14 in advance, the DNS server B1 can perform name resolution processing considering arbitrary user attribute information by referring to the user information database B14.

  As described above, in the conventional technique, the DNS server can use only the source IP address of the received DNS query message as attribute information regarding the user. Alternatively, when other attribute information is to be used, it is necessary to embed all necessary attribute information in the DNS query message transmitted by the client, and it is necessary to change the resolver in the client.

  In this embodiment, the DNS server B1 refers to the user information database B14, so that there is no need to change the resolver in the client. Further, even if the type of user attribute information considered for each DNS server is different, it was difficult to cope with the conventional technology, but the type of user attribute information registered in the user information database B14 according to this embodiment is different for each DNS server. It can be realized flexibly and easily just by changing to.

  Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 9, the second embodiment of the present invention includes a DNS server B3 and an authentication server E1 according to the present invention in addition to the client A1 and the network C1 shown in the first embodiment of FIG. Realized in preparation.

  In the second embodiment of the present invention, the management of the user information database B14 is automatically performed by the user information management unit B18, which is a component of the DNS server B3, in cooperation with the authentication server E1. This is different from the first embodiment. Hereinafter, a system including the client A1, the DNS server B3, and the authentication server E1 is referred to as this system.

  The authentication server E1 performs user authentication in response to an authentication request of a user (client A1) in the system, and permits or prohibits the user from logging into the system. The system here is not limited to this system, but refers to all of the systems where user authentication is performed when using, for example, a network operated by an ISP or a membership-based WEB service operated by an ASP (Application Service Provider). The users in this system are some or all of the users of the system here.

  The authentication server E1 performs user authentication, grasps the login status of the user whether the user (client A1) who transmitted the authentication request has logged in or logged out of the system, collects user attribute information, and collects these information. As a log. As an example of the user attribute information collected by the authentication server E1, as described in the description of the first embodiment, information on preferences such as location information, hobby or behavior history of the user (client A1), mobile Types of terminals used such as telephones, PDAs, notebook computers, OS installed on terminals, information on terminals used such as installed network interface, CPU speed, memory capacity, IP addresses of terminals used, ADSL lines, ISDN lines, etc. For example, information on the connection status to the network, such as connection line type, connection line speed, and IP address of the connected NAS.

  As an example of the authentication server E1, there is a RADIUS server widely used for user authentication and billing processing by an ISP or the like. The RADIUS server authenticates the user based on the ID and password included in the authentication request received from the user in the user authentication processing by the RADIUS protocol, and permits or prohibits the user login. The RADIUS protocol is used for user authentication not only in a network operated by an ISP but also in many network systems.

  In addition, whenever a user logs in or logs out of the network system, the RADIUS server sends a user login status and user attribute information to the RADIUS server. The RADIUS server collects such information for the purpose of billing and backtrace, and holds it as an Account Log. The user attribute information transmitted from the RADIUS client to the RADIUS server includes, for example, the login ID of the user's ISP, the IP address of the terminal used by the user, the IP address of the NAS to which the user is connected, and the connection line type. It is.

  The user information management unit B18 includes an authentication information acquisition unit B181 and a user information update unit B182.

  The authentication information acquisition unit B181 detects a change in the login status of the user, acquires information indicating the login status of the user and user attribute information from the authentication server E1, and passes these pieces of information to the user information update unit B182. The following two methods can be cited as examples of methods for detecting a change in the login status of a user and acquiring information indicating the login status of the user and user attribute information.

  In the first method, when the authentication server E1 detects a change in the login status of the user, the authentication server E1 notifies the authentication information acquisition unit B181 of information indicating the login status of the user and user attribute information. It is.

  The second method is that when the authentication information acquisition unit B181 inquires the authentication server E1 about the login status of the user to detect a change in the login status of the user, This is a method of acquiring information indicating user login status and user attribute information.

  In the first method, the authentication information acquisition unit B181 detects a change in the login status of the user by a passive process of waiting for a notification from the authentication server E1, whereas in the second method, the login status of the user is detected. In order to detect this change, the authentication information acquisition unit B181 performs an active process of inquiring the login status of the user to the authentication server E1.

  Hereinafter, specific examples of each method will be described.

  First, as a specific example of the first method, there is a method using the Proxy function and Relay function of the RADIUS protocol. The Proxy function is a function for transferring the information to another node every time the RADIUS server receives the user login status and user attribute information from the RADIUS client. The Proxy function is a standardized function and is implemented in almost all RADIUS servers currently used.

  FIG. 10 shows an example of a sequence when the user login status and attribute information are acquired using the Proxy function. FIG. 10 shows a sequence example when the user logs in to the system. In FIG. 10, the authentication server E1 is a RADIUS server. When the user authentication is successful and the user logs in to the system, an Accounting Request message is transmitted from the RADIUS client to the authentication server E1.

  In the Accounting Request message, user attribute information is included in the form of attribute = attribute value. In the example shown in the figure, in the Accounting Request message, the user ID is taro ((1) User Name = taro), and the NAS IP address is “30.30.30.30” ((4) NAS-IP-Address = 30.30.30.30), the IP address of the user terminal is 123.45.0.2 ((8) Framed-IP-Address = 123.45.0.2), and the connection line type is ADSL ((61 ) NAS-Port-Type = ADSL). Also included is information ((40) Acct-Status-Type = Start) indicating that the user has logged into the system.

  Upon receiving the Accounting Request message, the authentication server E1 uses the Proxy function to transmit the received Accounting Request message to the user information management unit B18. The user information management unit B18 acquires user attribute information from the received Accounting Request message. After receiving the Accounting Request message, the user information management unit B18 transmits an Accounting Response message to the authentication server E1.

  Next, acquisition of user information using the Relay function will be described. The Relay function is a function in which a RADIUS server transmits it to another node each time a new log is added to the Account Log. The Relay function is a de facto function and is implemented in many RADIUS servers.

  FIG. 11 shows an example of a sequence in the case where the login status and attribute information of the user are acquired using the Relay function. FIG. 11 shows a sequence when the user logs in to the system. In FIG. 11, the authentication server E1 is a RADIUS server. When the user authentication is successful and the user logs in to the system, a new log is added to the Account Log held by the authentication server E1. The authentication server E1 generates an Accounting Request message based on the newly added log and transmits it to the user information management unit B18.

  In FIG. 11, in the Accounting Request message, the user ID is taro ((1) User Name = taro), and the NAS IP address is “30.30.30.30” ((4) NAS-IP-Address = 30.30). .30.30), the IP address of the user terminal is 123.45.0.2 ((8) Framed-IP-Address = 123.45.0.2), and the connection line type is ADSL ((61) NAS- Port-Type = ADSL) is included. Also included is information ((40) Acct-Status-Type = Start) indicating that the user has logged into the system. The user information management unit B18 acquires user attribute information from the received Accounting Request message. After receiving the Accounting Request message, the user information management unit B18 transmits an Accounting Response message to the authentication server E1.

  Next, a specific example of the second method will be described. The authentication information acquisition unit B181 periodically transmits a message for inquiring about the login status of the user to the authentication server E1, and checks whether there is a change in the login status of the user. When there is a change in the user login status, the authentication server E1 is requested to transmit information indicating the user login status and user attribute information.

  More specific examples of the second method include a method using an NFS (Network File System) function and a method using an SNMP (Simple Network Management Protocol). NFS is a file service via a network that is generally used in a TCP / IP environment. By mounting a file held by another node connected to the network on its own node, it is as if a local file is stored. It has a function that can be handled. In the method using the NFS function, the user information management unit B18 mounts a log file including the user login status and user attribute information held by the authentication server E1. The authentication information acquisition unit B 181 detects a change in the login status of the user by periodically checking the log file mounted on the own node. When a change in the login status of the user is detected, user attribute information whose login status has changed is acquired from the mounted log file.

  On the other hand, SNMP is a protocol for managing and monitoring other nodes in a TCP / IP network environment. Management of other nodes is performed by exchanging management information called MIB (Management Information Base) between the “SNMP manager” on the management side and the “SNMP agent” on the management side. In the method using SNMP, the authentication information acquisition unit B181 serves as an SNMP manager, and the authentication server E1 is used as an SNMP agent to periodically check the portion indicating the login status of the user in the MIB of the authentication server E1. When a change in the login status of the user is detected, a part corresponding to the user attribute information whose login status has changed is acquired from the MIB of the authentication server E1.

  The user information update unit B182 manages the user information database B14 based on the information passed from the authentication information acquisition unit B182. For example, user attribute information of a user who has logged in to the system is added to the user information database B14, and user attribute information of a user who has logged out is deleted from the user information database B14.

  Next, the operation of the second embodiment will be described in detail with reference to the drawings. The operation from when the DNS server B1 receives the DNS query message from the client A1 to when it transmits the DNS response message is the same as the operation in the first embodiment shown in FIG. Hereinafter, the management of the user information database B14 in the user information management unit B18 will be described in detail with reference to FIG.

  When the authentication information acquisition unit B181 detects a change in the login status of the user (step S201 in FIG. 12), the authentication information acquisition unit B181 determines whether the change in the login status is a user login or logout (step S202).

  When the user logs in to the system, information indicating the login status of the user and user attribute information are acquired from the authentication server E1, and these pieces of information are passed to the user information update unit B182 (step S203). The user information update unit B182 investigates information indicating the login status of the user, and additionally registers user attribute information in the user information database B14 (step S204).

  If the user logs out from the system in step S202, the authentication information acquisition unit B181 acquires information indicating the login status of the user and user attribute information from the authentication server E1, and passes these information to the user information update unit B182 ( In step S205, the user information update unit B182 searches the user information database B14 for an entry corresponding to the user based on the user attribute information, and deletes the entry (step S206).

  In the above description of the second embodiment, the DNS server B1 includes the user information database B14 as its component. As another configuration, as in the first embodiment, a mode in which the user information database B14 is held in another server instead of the DNS server B1 is also conceivable. The configuration in this case is shown in FIG. 13 as another example of the second embodiment.

  In the configuration shown in FIG. 13, a DNS server B4 that does not include the user information database B14 is used instead of the DNS server B3 shown above, compared to the configuration shown in FIG. A database server D1 included as a component is used.

  In the configuration shown in FIG. 13, the conventional DNS server or the DNS servers B1, B2, B3, and B4 (including the DNS server B5 in the third embodiment to be described later) in the present invention are used as the database server D1. May be. In this case, the response database B16 in the DNS server is used as the user information database D11.

  In this case, as a method for updating the user attribute information in the user information database D11 by the user information update unit B182, a method using DNS Dynamic Update is conceivable. DNS Dynamic Update is a method for adding and deleting entries from other nodes to the database held by the DNS server. A node that performs DNS Dynamic Update encodes information to be added or deleted into a resource record format defined by DNS, and transmits a message in which the information is embedded to the DNS server. When the DNS server receives the message, the DNS server adds or deletes an entry to the held response database.

  In the method using the DNS Dynamic Update, the user information update unit B182 encodes the user attribute information passed from the authentication information acquisition unit B181 into a DNS resource record, and transmits a message in which this is embedded to the DNS server. When the DNS server receives the message, the DNS server adds or deletes an entry corresponding to the resource record embedded in the message from the response database (corresponding to the user information database D11). An example of an entry in the response database to be created is the zone file 302 shown in FIG.

  The operation of the DNS server B4 in the configuration shown in FIG. 13 can be similarly considered by replacing the user information database B14 with the user information database D11 in the above-described operation of the DNS server B3.

  Next, the effect of the second embodiment will be described.

  When the DNS server acquires and manages user attribute information necessary for customizing name resolution, it is very laborious and costly to manage the attribute information manually.

  For example, an ISP (Internet Service Provider) network has a huge number of users, and attribute information (location, IP address, connection line type, etc.) of each user changes dynamically. It is extremely difficult to manage.

  In the present embodiment, the user information management unit B18 manages the user information database B14 in cooperation with the authentication server E1. Registration and deletion of user attribute information in the user information database B14 is automatically performed by the user information management unit B18. For this reason, the effort and cost required for setting management (registration and deletion of user attribute information) of the user information database B14 can be reduced as compared with the first embodiment.

  In the present embodiment, the authentication information acquisition unit B181 acquires user information from the authentication server E1, but no special function is required for the authentication server when acquiring user information. As a method for acquiring user information, the method using the proxy function or relay function of the RADIUS server, the method using NFS, and the method using SNMP are shown as examples. However, these functions are functions that are standardized or de facto. Yes, it is a function that can be used only by changing the settings in many authentication servers used today. Therefore, when this system is introduced into an existing system, there is no need for installation costs such as installing a new authentication server or replacing the existing authentication server with a dedicated authentication server. Further, even after the introduction of this system, authentication processing and log collection are performed by the same authentication server, so there is no cost for changing the operation mode such as authentication processing and billing processing in the existing system.

  Next, a third embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 14, the third embodiment of the present invention includes a DNS server B5 and a packet transfer device F1 in addition to the client A1 and the authentication server E1 shown in the second embodiment of FIG. Realized. The DNS server B5, the authentication server E1, and the packet transfer device F1 are interconnected by a network C1. Packets transmitted and received by the client A1 with the network C1 always pass through the packet transfer device E1. Here, the packet transfer device refers to all devices having a packet transfer processing function, such as an Ethernet (registered trademark) switch, an ATM switch, a router, a layer 4 switch, and a layer 7 switch.

  The DNS server B5 is different from the configuration of the DNS server B1 in the first embodiment shown in FIG. 1 in that the user information acquisition unit B13 and the user information database B14 are not required as components. Hereinafter, although the configuration including the DNS server B5 will be described, any of the DNS servers B1, B2, B3, and B4 shown in the first and second embodiments may be used instead of the DNS server B5.

  An example of contents registered in the response database B16 is shown in FIG. The response database B16 includes a name resolution table 401 and zone files 402 and 403. The name resolution table 401 and the zone file 402 (or 403) respectively correspond to the name resolution table 201 and the zone file 202 (or 203) in FIG. 3 described in the first embodiment of the present invention.

  Here, in the third embodiment, as the user attribute information, in addition to the example of the user attribute information described in the first and second embodiments, the attribute information related to the packet transfer device is handled. . That is, the name resolution table 401 includes not only attribute information such as a user ID and connection line type but also attribute information related to the packet transfer device F1 as user attribute information, as compared to the name resolution table 201. The point that the reference destination of the name resolution method can be registered also for each information is different. Here, as an example of attribute information related to the packet transfer device F1, an identifier (ID) of the packet transfer device F1, a transfer method supported by the packet transfer device F1 (for example, support of vlan of Ethernet (registered trademark), URL Information such as whether to support base switching).

  The name resolution table 401 shown in FIG. 15 includes not only attribute information such as a user ID, a connection line type, and a group ID as a user attribute, but also a packet transfer device ID, and the name resolution method is referenced for each packet transfer device ID. The destination can be registered. The zone file 402 (or 403) has a field (Additional Data) for storing additional information in each entry in addition to the fields (Type, FQDN, and Data) shown in the zone file 202 (or 203). Is different.

  In this embodiment, the field for storing this additional information is used for storing a transfer method for the packet in the packet transfer apparatus F1. As an example of a transfer method for a packet, a priority for transferring the packet (packet transfer priority), an ID (logical network ID) of a logical network (VPN (Virtual Private Network), vlan, etc.) to which the packet is to be transferred, ID of logical channel (VCI (Virtual Channel Identifier) of ATM), MPLS (Multi Protocol Label Switching) of MPLS (Label Switched Path), etc., rewrite / addition / deletion method for the header of the packet, etc. Is mentioned.

  In the first entry in the zone file 402, www. ddd. The response of the A record to com is “20.1.1.1”, and further, a packet with the destination IP address “20.1.1.1” transmitted as a result of the client A1 referring to the entry On the other hand, in the packet transfer apparatus F1, the source IP address (SrcIPAddr) is rewritten to “40.1.1.1”, the vlan-ID (vlanID) in the MAC header is rewritten to “111”, and the output port 21 It shows that a transfer method of transferring at a normal transfer priority (priority) is used.

  When creating the DNS response message for the DNS query message, if the Additional Data field is registered in the entry in the response database B16 that is referred to, the response creating unit B15 creates a DNS response message in the created DNS response message. The contents written in Additional Data are stored. As this storage method, there is a method of storing the contents described in the Additional Data in the additional information part in the DNS message described above.

  By storing the contents described in the Additional Data in the additional information section of the DNS response message, the response message is not only the IP address (or other resource record data) for the FQDN inquired from the client A1, A transfer method for a packet transmitted from the client A1 to the IP address in the packet transfer apparatus F1 can be included at the same time.

  The packet transfer device F1 includes a user authentication unit F11, a user information update unit F12, a user information database F13, a user information acquisition unit F14, a DNS proxy unit F15, a routing table F16, and a forwarding unit F17.

  The user authentication unit F11 has a function of identifying and authenticating a user in the client A1 connected to the packet transfer apparatus F1. Furthermore, various user attribute information of the user obtained at the time of authentication is stored in the user information database F13 via the user information update unit F12. A typical example of performing user authentication in the packet transfer apparatus F1 is IEEE 802.1x which is a user authentication mechanism standardized in an Ethernet (registered trademark) switch.

  When the packet transfer apparatus F1 supports IEEE 802.1x, the user authentication unit F11 communicates with the authentication server C1 using the RADIUS protocol based on information such as the user ID and password of the user on the client A1. By performing authentication, it is determined whether or not the client A1 should be allowed to communicate with the network C1 side.

  The user information update unit F12 manages the user information database F13 based on the information passed from the user authentication unit F11. For example, the user attribute information of the user who logs in to the packet transfer apparatus F1 and performs communication is added to the user information database F13, and the user attribute information of the logged out user is deleted from the user information database F13.

  The user information database F13 is a database that stores user attribute information of a user authenticated by the user authentication unit F11. An example of user attribute information stored in the user information database F13 is the same as the example of user attribute information described in the first embodiment. An example of the user information database is shown in a user information database 501 in FIG. In the user information database 501, the user ID, connection line type, connection line speed, and group ID of the packet are described for the input port and source MAC address corresponding to the packet received by the packet transfer apparatus F1.

  For example, in the first entry, for a packet whose input port is “02” and the source MAC address is “00: 12: 34: 56: 78: 9a”, the user ID of the sender of the packet is “Taro”, the type of the connected line is Ethernet (registered trademark), the speed is 100 Mbps, and the ID of the group including the packet sender is “silver”. .

  The user information acquisition unit F14 acquires, from the user information database F13, user attribute information corresponding to the sender of the DNS query message received by the query rewriting unit F151 in the DNS proxy unit F15, and the user attribute information is the query rewriting unit. It has a function to pass to F151.

  The DNS proxy unit F15 has a function of reading and analyzing the contents of a DNS query message and a DNS response message flowing between the client A1 and the DNS server B5, and rewriting and transmitting the contents of the message. The DNS proxy unit F15 includes a query rewriting unit F151 and a response analysis unit F152 as its components.

  The query rewriting unit F151 adds, to the DNS query message, user attribute information related to the user who transmitted the DNS query message to the DNS query message transmitted from the client A1 to the DNS server B5. It has a function to transmit to. At this time, attribute information related to the packet transfer apparatus F1 can be included in the user attribute information as necessary. Here, the user attribute information related to the user who transmitted the DNS query message is acquired from the user information database F13 via the user information acquisition unit F14, and attribute information related to the packet transfer apparatus F1 is added as necessary.

  The response analysis unit F152 has a function of extracting the packet transfer method embedded in the message from the DNS response message transmitted from the DNS server B5 to the client A1. Further, an entry corresponding to the extracted packet transfer method is registered in the routing table F16.

  The routing table F16 is a database that stores a method for transferring packets received by the forwarding unit F17. Examples of the table indicated by the routing table F16 include a table storing a transfer method of a received packet in a router, a table storing a switching method in an Ethernet (registered trademark) switch, and the like. The entry in the routing table F16 is created by the response analysis unit F152 in addition to a method that is statically set or created based on information dynamically obtained by a routing protocol as in the prior art. Is also possible.

  An example of the contents of the routing table F16 is shown in FIG. In the second entry in the routing table F16, the input port, source MAC address, destination IP address, and vlan-ID of the packet received by the packet transfer device F1 are “11”, “00: bc: de: f0: 12: 34 ”,“ 60.1.1.1 ”, and“ 200 ”, the source IP address, the destination IP address, and the vlan-ID are respectively“ 40.1.1.1 ”for the packet. , “90.1.1.1”, “333”, and transmission from the output port “31”. Furthermore, the priority is “priority”, which indicates that transmission is performed with a higher packet transfer priority.

  The forwarding unit F17 has a function of solving the transfer method of the packet received by the packet transfer device F1 and transferring the packet based on the transfer method. The transfer method of the received packet here is solved by referring to the routing table F16.

  Next, in the present embodiment, the operations of the packet transfer apparatus F1 and the DNS server B5 until the client A1 transmits a DNS query message to the DNS server B5 and the corresponding DNS response message is returned to the client A1 are illustrated. Will be described in detail with reference to FIG.

  First, the operation of the packet transfer apparatus F1 when the client A1 transmits a DNS query message to the DNS server B5 will be described with reference to the flowchart of FIG.

  When the client A1 transmits a DNS query message to the network C1 side, the packet transfer apparatus F1 detects the message and receives the message. The DNS query message received by the packet transfer device F1 is passed to the query rewriting unit F151 in the DNS proxy unit F15 (step S301 in FIG. 18).

  Here, since the IP address of the DNS server B5 is designated as the destination IP address in the message, a method of passing only the message to the query rewriting unit F151 without transferring it in the same manner as a normal packet is required. . As this method, only a packet having a specific port number indicating that it is a DNS query message is passed to the query rewriting unit F151 (in general, a DNS query message is identified based on a packet having a destination port number of 53). Can be).

  Next, the query rewriting unit F151 searches for user attribute information of the sender of the received DNS query message by referring to the user information database F13 (step S302).

  For example, if the user information database F13 stores the same entry as the user information database 501 shown in FIG. 16, it is received from the port 11 and the source MAC address is “00: bc: de: f0: 12: 34”. The DNS query message “” refers to the user information database F13 so that the user ID of the sender is “hanako”, the type of connection line is Ethernet (registered trademark), the speed of the connection line is 10 Mbps, etc. User attribute information is retrieved. The group ID item is “-”, indicating that the group ID is unknown or an attribute that does not need to be acquired.

  If there is user attribute information corresponding to the sender of the received DNS query message as a result of the search for user attribute information in step S302, the corresponding user attribute information is added to the DNS query message by the query rewriting unit F151, The message is transmitted to the DNS server B5 (steps S303 and S304).

  In step S304, in addition to the user attribute information resolved with reference to the user information database F13, if it is necessary to add attribute information related to the packet transfer device F1 to the DNS query message as user attribute information, the packet transfer device F1 Is added to the message and transmitted to the DNS server B5. For example, in addition to the user attribute information resolved with reference to the user information database F13, the ID of the packet transfer device F1 is added to the message.

  If the user attribute information corresponding to the sender of the received DNS query message does not exist as a result of the search for the user attribute information in step S302, the query rewriting unit F131 adds any information to the message. Instead, it is transmitted to the DNS server B5 as it is (steps S303 and S305).

  Next, the operation in the DNS server B5 when the DNS server B5 receives the DNS query message via the packet transfer device F1 will be described with reference to FIG.

  First, when the query receiving unit B11 receives a DNS query message (step S401 in FIG. 19), the query receiving unit B11 passes the message to the user information identifying unit B12.

  The user information identification unit B12 identifies whether the user attribute information of the sender is embedded in the received DNS query message (step S402).

  As a result of step S402, when the user attribute information of the sender is embedded in the message, the user attribute information of the embedded sender is read and identified, and the message is sent together with the identified user attribute information. The message is passed to the response creation unit B15 (step S403).

  As a result of step S402, if the sender's user attribute information is not embedded in the message, the message is passed to the response creating unit B15 on the assumption that there is no sender's user attribute information corresponding to the message.

  After Steps S402 and S403, the operations of Steps S404 to S408 are the same as Steps S103 to S107 of FIG. 4 described in the first embodiment.

  In step S408, if the packet transfer method in the packet transfer device F1 is also added to the DNS response message generated by the response generation unit B15, the response transmission unit B17 includes the DNS including the packet transfer method in the packet transfer device F1. A response message is transmitted to the client A1.

  Next, the operation when the packet transfer apparatus F1 receives a DNS response message from the DNS server B5 will be described with reference to the flowchart of FIG.

  When the DNS server B5 transmits a DNS response message to the client A1, the packet transfer device F1 detects the message and receives the message. The DNS response message received by the packet transfer device F1 is passed to the response analysis unit F152 in the DNS proxy unit F15 (step S501 in FIG. 20).

  Here, since the address of the client A1 is specified as the destination IP address in the message, it is necessary to provide a method of passing only the message to the response analysis unit F152 without transferring it in the same manner as a normal packet. This method can be considered in the same way as the method described in the explanation of the operation in step S301 in FIG. 18 (the DNS response message can be identified based on the packet having the source port number 53).

  Next, the response analysis unit F152 checks the content of the received DNS response message, and checks whether or not the packet transfer method in the packet transfer device F1 is embedded in the message (step S502).

  As a result of step S502, when the packet transfer method is embedded, the response analysis unit F152 reads the embedded packet transfer method (step S503). Hereinafter, a description will be given of a case where a DNS response message is created in the DNS server B5 using the first entry in the zone file 402 shown in FIG. 15, and the message is transmitted from the DNS server B5 to the client A1.

  Next, the response analysis unit F132 refers to the entry registered in the routing table F16 and determines whether there is an entry identical to the entry created from the packet transfer method embedded in the received DNS response message. Check (steps S504 and S505).

  If there is no entry indicating the same transfer method as a result of step S505, the response analysis unit F152 creates an entry corresponding to the packet transfer method embedded in the received DNS response message in the routing table F16. (Step S506).

  Here, an example of creating an entry indicating the packet transfer method in the routing table F16 is shown. The DNS server B5 creates a DNS response message using the first entry of the zone file 402 in the response database B16 shown in FIG. 15, and the packet transfer apparatus F1 receives the message transmitted to the client A1. Suppose that Further, the MAC address of the client A1 that is the transmission destination of the message is “00: 12: 34: 56: 78: 9a”, and the port “of the packet transfer device F1 between the client A1 and the packet transfer device F1 is“ When the data is transferred using the Ethernet (registered trademark) vlan whose vlan-ID is “100” via “02”, the first entry in the routing table F16 illustrated in FIG. 17 is created.

  If there are entries indicating the same transfer method as a result of step S505, the operation of step S506 is skipped in order to avoid creating duplicate entries.

  Next, the response analysis unit F152 deletes the packet transfer method embedded in the received DNS response message from the message (step S507), and transfers the message to the client A1 (step S508).

  If it is determined in step S502 that the packet transfer method is not embedded, the response analysis unit F152 transfers the received DNS response message to the client A1 as it is (step S508).

  In the present embodiment described above with reference to FIG. 14, the user information database F13 in the packet transfer apparatus F1 uses the user attribute information obtained during authentication between the user authentication unit F11 and the authentication server E1 as the user. It was created by storing the authentication unit F11 via the user information update unit F12. In addition, a mode in which user attribute information is manually written in the user information database F13 from the outside by an administrator of the packet transfer apparatus F1 or the like is also conceivable. In this case, the user authentication unit F11, the user information update unit F12, and the authentication server E1 are not necessary as components in the present embodiment.

  In the third embodiment described with reference to FIG. 14, the packet transfer apparatus F1 includes the user information database F13 as its component. As another configuration, a form in which the user information database F13 is held not in the packet transfer device F1 but in another server (external database or the like) is also conceivable. The configuration in this case is shown in FIG. 21 as another example of the third embodiment.

  In the configuration shown in FIG. 21, a packet transfer device F2 that does not include the user information database F13 is used instead of the packet transfer device F1 shown above, compared to the configuration shown in FIG. In the explanation of the embodiment, the database server D1 shown in FIG. 7 is used. The function of the database server D1 can be realized as one function of the DNS server B1, B2, or B5, as described in the first embodiment. In this case, the user information acquisition unit F14 acquires user attribute information using a DNS message.

  The operation of the packet transfer apparatus F2 in the configuration shown in FIG. 21 can be similarly considered by replacing the user information database F13 with the user information database D11 in the description of the operation of the packet transfer apparatus F1 described above.

  Furthermore, in the present embodiment described with reference to FIG. 14, the configuration in which the DNS proxy unit F15 of the packet transfer apparatus includes both the query rewriting unit F151 and the response analysis unit F152 has been described. A configuration having only one of the query rewriting unit F151 and the response analysis unit F152 is also conceivable.

  FIG. 22 shows a configuration example of the packet transfer device F3 in which the DNS proxy unit F15 includes only the query rewriting unit F151. In the case of this configuration, the packet transfer device F3 embeds the user attribute information of the sender in the DNS query message received from the client A1 and transmits it to the DNS server B5, while in the DNS response message returned from the DNS server B5. On the other hand, it transmits to the client A1 as it is.

  FIG. 23 shows a configuration example of the packet transfer device F4 in which the DNS proxy unit F15 includes only the response analysis unit F152. In the case of this configuration, the packet transfer device F4 transmits the DNS query message received from the client A1 as it is to the DNS server B5, while embedding the DNS response message returned from the DNS server B5. The packet transfer method is extracted and an entry is created in the routing table.

  Next, the effect of the third embodiment will be described.

  In the present embodiment, the DNS query message transmitted from the client A1 to the DNS server B5 is temporarily received by the packet transfer apparatus F1, and the user attribute information relating to the user who transmitted the DNS query message is stored in the DNS query message. Embed in. At this time, attribute information related to the packet transfer device F1 is also embedded as user attribute information as necessary and transferred to the DNS server B5. Further, when the DNS server B5 receives the DNS query message, the DNS server B5 determines the DNS response and the packet transfer method in the packet transfer apparatus F1 corresponding to the response based on the user attribute information embedded in the DNS query message. Embedded in and transmitted to the client A1. The packet transfer device F1 receives the response message once, extracts the packet transfer method embedded in the response message, and creates an entry corresponding to the routing table F16.

  Conventionally, the DNS response message transmitted from the DNS server to the client has been used by the client. However, according to the present embodiment, not only the client but also the packet transfer installed between the client and the DNS server. The device can also use the information stored in the DNS response message.

  In the present embodiment, the transfer method in the packet transfer apparatus F1 for the packet transmitted by the client as a result of receiving the response message is embedded in the DNS response message. Thus, for example, in the case of a Web application, the client A1 is connected to a Web server with a low load, and at the same time, the packet transfer device F1 preferentially transfers a packet passing over the connection between the client A1 and the Web server The DNS server can perform control such as making

  Further, by the DNS response customization function described in the first embodiment of the present invention, the transfer method control in the packet transfer apparatus F1 is similarly customized based on the user attribute information and the attribute information related to the packet transfer apparatus F1. Is possible. For example, it is possible to perform control such that a packet transmitted / received by a privileged user is preferentially transferred or transferred using a vlan for the privileged user.

  Next, a first embodiment of the present invention will be described with reference to the drawings. This example corresponds to the first embodiment of the present invention. In addition, the present embodiment assumes the configuration shown in FIG. In the embodiment, the client A1 is a terminal used by a user who requests name resolution from the DNS server B1. The DNS server B1 holds the contents shown in FIG. 2 as the user information database B14, and holds the name resolution table 201 and the zone files 202 and 203 shown in FIG. 3 as the response database B16.

  Now, the user 1 who uses the terminal whose IP address is “123.45.0.2” and the user 2 who uses the terminal whose IP address is “123.45.0.4” are FQDN: www. aaa. Suppose that the DNS server B1 is requested to resolve the name of the com. www. aaa. com is a FQDN of a website that provides regional information. In such a website, the location information of the accessing user (IP address of the connected NAS) and the type of connection line to the network are considered. It is assumed that a service for displaying a web page suitable for the user attribute information is provided.

  Specifically, a user connected to the network from Kawasaki City (hereinafter, a user connected to the NAS whose IP address is “30.30.30.30” is a user connected to the network from Kawasaki City. Is provided with local information of Kawasaki City, and users connected to the network from Yokohama City (in the following, users connected to NAS with IP address “20.20.20.20” are Yokohama City) The local information of Yokohama city is provided to the user who is connected to the network.

  For users connected via an ADSL line, regional information is displayed on a web page mainly composed of multimedia contents suitable for broadband access, and conversely for users connected to a network via an ISDN line. Is displayed by a web page mainly composed of text-based content suitable for narrowband access. These web pages are assumed to be hosted on different web servers, and in the following, the web page for users connected to the network from Kawasaki City via an ADSL line is the web server with the IP address “9.8.7.6”. In addition, it is assumed that a web page for a user who is network-connected from Yokohama City via an ISDN line is hosted on a web server having an IP address “9.8.7.3”.

  First, the user 1 and the user 2 transmit a DNS query message to the DNS server B1 through their use terminals. The query reception unit B11 of the DNS server B1 passes the received DNS query message to the user information identification unit B12. Since the user attribute information is not embedded in the DNS query message, the user information identification unit B12 passes the DNS query message to the user information acquisition unit B13. The user information acquisition unit B13 first checks the source IP address of the received DNS query message. In this case, the source IP address of the DNS query message transmitted by the user 1 is “123.45.0.2”, and the source IP address of the DNS query message transmitted by the user 2 is “123.45.0.4”. It is.

  Next, based on the source IP address, the user information database B14 is searched for entries corresponding to the user 1 and the user 2. In this case, the entry corresponding to the user 1 is the first entry in the user information database B14 shown in FIG. 2. As the attribute information of the user 1, the login ID is “taro”, the connection line type is the ADSL line, the connection The information that the IP address of the NAS being “30.30.30.30” is obtained.

  The entry corresponding to the user 2 is the second entry in the user information database B14. As the attribute information of the user 2, the login ID is hanako and the IP address is “123.45.0.4”. The information that the IP address of the existing NAS is “20.20.20.20” is obtained. Furthermore, it can be seen that other attribute information can be obtained by referring to the node whose IP address is “8.9.1.4”. Here, it is assumed that the user information acquisition unit B13 refers to the node having the IP address “8.9.1.4” and obtains information that the connection line type is an ISDN line as the attribute information of the user 2.

  The user information acquisition unit B13 passes the attribute information of the user 1 and the user 2 obtained as described above to the user information identification unit B12, and the user information identification unit B12 further transmits the attribute information of the user 1 and the user 2 Then, the DNS query message transmitted from the user 1 and the user 2 passed from the query receiving unit B11 is passed to the response creating unit B15. The response creation unit B15 searches the response database B16 for an entry corresponding to the user attribute information and the FQDN for which an inquiry has been made.

  In this case, the first entry in the name resolution table 201 shown in FIG. 3 is found as an entry corresponding to the DNS query from the user 1, and the first entry in the zone file 202 is found as a name resolution method. Is done. As a result, the FQDN of the user 1: www. aaa. For the DNS query to com, the IP address “9.8.7.6” is resolved.

  In addition, a second entry in the name resolution table 201 is found as an entry corresponding to the DNS query message of the user 2, and a first entry in the zone file 203 is found as a name resolution method. As a result, user 2's FQDN: www. aaa. For the DNS query to com, the IP address “9.8.7.3” is resolved.

  The response creation unit B17 passes the name resolution result to the response transmission unit B17. The response transmission unit B17 embeds the received name resolution result in the DNS response message and transmits it to the user 1 and the user 2.

  When the user 1 receives the DNS response message from the DNS server B1, the user 1 accesses the web server whose IP address is “9.8.7.6”. As described above, the web server with the IP address “9.8.7.6” hosts a web page suitable for a user connected to the network from the Kawasaki city through an ADSL line. A web page suitable for one attribute is displayed.

  Similarly, when the user 2 receives the DNS response message from the DNS server B1, the user 2 accesses the web server whose IP address is “9.8.7.3”. As described above, the web server with the IP address “9.8.7.3” hosts a web page suitable for a user connected to the network from the city of Yokohama via an ISDN line. A web page suitable for the second attribute is displayed.

  Next, a second embodiment will be described with reference to the drawings. Such an example corresponds to the second embodiment. Further, the present embodiment assumes the configuration shown in FIG. In this embodiment, the authentication server E1 is a RADIUS server, and is used for user authentication and billing processing of a user who logs in to a network operated by an ISP. The client A1 is a terminal used by a user who logs in to a network operated by the ISP. The user requests the DNS server B3 for name resolution using the client A1.

  Now, assume that a user logs in to a network operated by an ISP. As shown in FIG. 9, when the user logs in, the authentication server E1 receives the Accounting Request message from the RADIUS client, and transfers the received Accounting Request message to the DNS server B3 using the Proxy function. Here, in the Accounting Request message, as shown in FIG. 9, as the user attribute information, the user's login ID is taro, the connected NAS's IP address is 30.30.30.30, and the user's terminal ( It is described that the IP address of the client A1) is 123.45.0.2, the connection line type is an ADSL line, and that the user has logged into the network.

  When the authentication information acquisition unit B181 of the user information management unit B18 receives the Accounting Request message, it passes it to the user information management unit B182. In this case, since the Accounting Request message describes that the user has logged in to the network, the user information management unit B182 registers the user attribute information described in the Accounting Request message in the user information database B14. As a result, for example, the first entry of the user information database shown in FIG. 2 is added to the user information database B14. The operation when the user requests name resolution from the DNS server B1 after logging in to the network is the same as in the first embodiment described above.

  Next, a third embodiment of the present invention will be described with reference to the drawings. Such an example corresponds to the third embodiment of the present invention. Further, the present embodiment assumes the configuration shown in FIG. In the embodiment, the client A1 is a terminal used by a user who requests name resolution from the DNS server B5. The DNS server B5 holds the name resolution table 401 and zone files 402 and 403 shown in FIG. 15 as a response database B16, and the packet transfer device F1 has a NAT (Network Address Translation) function, as shown in FIG. The contents are held as a user information database F13. Further, it is assumed that the identifier (ID) of the packet transfer device F1 is “switch99”.

  Now, with the user 1 who uses a terminal connected with a vlan whose MAC address is “00: 12: 34: 56: 78: 9a” and the port “02” of the packet transfer apparatus F1 is vlanID “100”. , Each of the users 2 using the terminals connected to the port “11” of the packet transfer apparatus F1 with the vlan ID “200” and the vlan ID “200: bc: de: f0: 12: 34”. Http: // www. ddd. com / index. Assume that a user accesses a Web site having an html URL.

  First, the client A1 corresponding to the terminal used by the user 1 or the user 2 has an FQDN: www. ddd. com to send a DNS query message to the DNS server B5. When the DNS query message passes through the packet transfer device F1, the packet transfer device F1 passes a packet that matches the destination port number (53) of the DNS message to the query rewriting unit F151 in the DNS proxy unit F15. The query rewriting unit F151 acquires user attribute information corresponding to the sender of the query message from the user information database F13 via the user acquisition unit F14.

  For user 1, it matches the first entry in user information database 501, and for user 2, it matches the second entry. The query rewriting unit F151 embeds the acquired user attribute information and the ID (“switch99”) of the packet transfer device F1 in the additional information part of the received DNS query message, and transfers them to the DNS server B5.

  When the DNS server B5 receives the DNS query message in which the user attribute information is embedded, the user information identification unit B12 identifies the user attribute information embedded in the DNS query message, and the response creation unit B15 Search for entries corresponding to attribute information and query contents. In the case of a DNS query message from the user 1, it matches the first entry of the name resolution table 401 in the response database B16, and further matches the first entry of the zone file 402 as the name resolution method.

  As a result, the FQDN of the user 1: www. ddd. In the DNS response message returned in response to the DNS query message to com, the IP address 20.1.1.1 is entered in the response unit, and “SrcIPAddr” is a transfer method in the packet transfer apparatus F1 for the corresponding packet. = 40.1.1.1, vlanID = 111, output = 21, priority = 0 ”is entered in the additional information section. In the case of the DNS query message of the user 2, it matches the third entry of the name resolution table 401, and further matches the first entry of the zone file 403 as the name resolution method.

  As a result, user 2's FQDN: www. ddd. In the DNS response message that is replied to the DNS query message to com, the IP address “60.1.1.1” is entered in the response unit, and the packet transfer apparatus F1 transfers the corresponding packet. “SrcIPAddr = 40.1.1.1, DestIPAddr = 90.1.1.1, vlanID = 333, output = 31, priority = 1” is entered in the additional information section. The DNS response message created by the response creation unit B15 is transmitted to the client A1 (user 1 or user 2) by the response transmission unit B17.

  The DNS response message transmitted from the DNS server B5 to the client A1 passes through the packet transfer device F1 on the way. When the response message passes through the packet transfer device F1, the packet transfer device F1 passes a packet matching the source port number (53) of the DNS message to the response analysis unit F152 in the DNS proxy unit F15. The response analysis unit F152 analyzes the information included in the response message and creates an entry in the routing table F16 based on the information.

  In the case of the DNS response message to the user 1, the first entry of the content example shown in FIG. 17 is created in the routing table F16 based on the information included in the response part and the additional information part of the response message. Also, in the case of a DNS response message to the user 2, the second entry of the content example shown in FIG. 17 is created in the routing table F16 based on the information included in the response part and additional information part of the response message. The

  When the response analysis unit F152 creates an entry in the routing table F16, the response analysis unit F152 deletes the additional information unit field in the received DNS response message and transfers it to the client A1.

  When the client A1 receives the DNS response message corresponding to the transmitted DNS query message, the client A1 responds to the www. ddd. An HTTP connection is established with respect to the IP address of com, and a request process or the like is performed on the connection. For user 1, an HTTP connection is established for IP address “20.1.1.1”, and for user 2, an HTTP connection is established for IP address “60.1.1.1”. . All of the packets flowing on these connections pass through the packet transfer device F1.

  At this time, for the packet flowing on the connection between the user 1 and the IP address “20.1.1.1”, the transfer method based on the first entry in the routing table 601 of FIG. And the IP address “60.1.1.1”, a transfer method based on the second entry in the routing table F16 is applied.

  For example, the packet transmitted by the user 1 is transferred with the normal transfer priority because the transfer priority is “normal” in the routing table F16. However, the packet transmitted by the user 1 is transferred with the transfer priority. Since the priority is “priority”, the transfer is performed with priority over packets transferred with the normal transfer priority. That is, it is expected that the user 2 can make a smooth Web connection compared to the user 1.

  According to the present embodiment, by using the DNS server B5 and the packet transfer device F1, not only the FQDN to IP address resolution function provided by the conventional DNS server but also the packet transfer device F1 through which the packet transmitted by the client A1 passes. It can be seen that the packet transfer method in FIG.

  The DNS server and packet transfer apparatus of the present invention realizes the function of each component, which is a component, in hardware, as well as the name resolution program that executes the function of each device described above and performs name resolution processing ( Application) is loaded into a memory of a computer processing apparatus that implements the DNS server and executed. That is, the functions of the DNS server and the packet transfer apparatus described above can be realized by software. The name resolution program is stored in a magnetic disk, a semiconductor memory, or other recording medium, loaded from the recording medium to a computer processing unit, and controls the operation of the computer processing unit, thereby realizing each function described above.

  Although the present invention has been described with reference to the preferred embodiments and examples, the present invention is not necessarily limited to the above-described embodiments and examples, and various modifications can be made within the scope of the technical idea. Can be implemented.

It is a block diagram which shows the structure of the 1st Embodiment of this invention. It is a figure which shows the example of the user information database of the 1st Embodiment of this invention. It is a figure which shows the example of the database for a response of the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the DNS server of the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement of acquisition of the user attribute information of the DNS server in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the response preparation part in the DNS server in the 1st Embodiment of this invention. It is a block diagram which shows the structure in case the database server hold | maintains a user information database in the 1st Embodiment of this invention. It is a figure which shows the example of the database for a response in which the user attribute information of the 1st Embodiment of this invention is registered. It is a block diagram which shows the structure of the 2nd Embodiment of this invention. An example of a message sequence when the authentication information acquisition unit acquires user attribute information from the authentication server using the proxy function of the RADIUS protocol when the authentication server is a RADIUS server in the second embodiment of the present invention is shown. It is a sequence diagram. An example of a message sequence when the authentication information acquisition unit acquires user attribute information from the authentication server using the relay function of the RADIUS server when the authentication server is a RADIUS server in the second embodiment of the present invention is shown. It is a sequence diagram. It is a flowchart which shows operation | movement of the user information management part in the 2nd Embodiment of this invention. It is a block diagram which shows the structure in case the database server hold | maintains a user information database in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the 3rd Embodiment of this invention. It is a figure which shows the example of the database for a response of the 3rd Embodiment of this invention. It is a figure which shows the example of the user information database of the 3rd Embodiment of this invention. It is a figure which shows the example of the routing table of the 3rd Embodiment of this invention. It is a flowchart which shows operation | movement of the packet transfer apparatus at the time of receiving the DNS query message from the client in the 3rd Embodiment of this invention. It is a flowchart which shows operation | movement of the DNS server of the 3rd Embodiment of this invention. It is a flowchart which shows operation | movement of the packet transfer apparatus at the time of receiving the DNS response message from the DNS server in the 3rd Embodiment of this invention. It is a block diagram which shows the structure in case the database server hold | maintains a user information database in the 3rd Embodiment of this invention. It is a block diagram which shows the other structural example in the 3rd Embodiment of this invention. It is a block diagram which shows the further another structural example in the 3rd Embodiment of this invention.

Explanation of symbols

A1: Client B1: DNS server B11: Query reception unit B12: User information identification unit B13: User information acquisition unit B14: User information database B15: Response creation unit B151: Response creation main unit B152: Resolver unit B16: Response database B17 : Response transmission unit B18: User information management unit B181: Authentication information acquisition unit B182: User information management unit B2: DNS server B3: DNS server B4: DNS server B5: DNS server C1: Network D1: Database server D11: User information database E1: Authentication server F1: Packet transfer device F11: User authentication unit F12: User information update unit F13: User information database F14: User information acquisition unit F15: DNS proxy unit F151: Query rewriting unit F1 2: Response analysis unit F16: Routing table F17: Forwarding unit F2: Packet forwarding device 201: Name resolution table 202: Zone file 203: Zone file 301: Name resolution table 302: Zone file 401: Name resolution table 402: Zone file 403 : Zone file 601: Routing table

Claims (17)

A packet transfer apparatus having a function of transferring a received packet to another node;
A name resolution system comprising: a name resolution server that performs name resolution on a received name resolution request message and returns a result of the name resolution by a name resolution response message;
The name resolution request message transmitted from the client to the name resolution server is once received by the packet transfer device,
A DNS proxy unit that temporarily receives the name resolution request message, acquires attribute information about a sender of the name resolution request message, and transmits the name resolution request message to which the attribute information is added to the name resolution server; And
The name resolution server, based on the attribute information contained in the name resolution request sent by the packet transfer device, name resolution the name will be returned to the name resolution response message is the result of solving, characterized in that system. The packet transfer device includes:
A user information database storing the attribute information is provided as an internal element,
The name resolution system according to claim 1, wherein attribute information related to a user who is a sender of the name resolution request message is acquired from the user information database.   The name resolution system according to claim 1, wherein the packet transfer apparatus acquires the attribute information from an external database server including a user information database in which the attribute information is stored.   4. The name resolution system according to claim 3, wherein the packet forwarding apparatus uses a name resolution request message in acquiring the attribute information from the external database server.   5. The name resolution system according to claim 3, wherein the external database server is a name resolution server installed outside. The packet transfer apparatus further includes a user authentication unit for identifying and authenticating a user in a client connected to the own node;
6. The apparatus according to claim 1, further comprising: a user information update unit that updates contents of the user information database based on attribute information about the user obtained at the time of authentication. Name resolution system. The said packet transfer apparatus acquires the attribute information regarding the sender of the said name resolution request message based on the transmission source address contained in the said name resolution request message, The any one of Claim 1-6 The name resolution system described in the section. A name resolution method in which a name resolution server performs name resolution on a name resolution request message sent by a client and returns a result of the name resolution by a name resolution response message.
A packet transfer apparatus having a function of transferring a received packet to another node, which exists between the client and the name resolution server, is received once by the name resolution request message transmitted from the client to the name resolution server. And
Attribute information about the user who is the sender of the name resolution request message is acquired by the packet transfer device based on a source address included in the name resolution request message, and the attribute information is added to the name resolution request message. The name resolution request message is sent to the name resolution server after
The name resolution server, based on the attribute information contained in the name resolution request sent by the packet transfer device, name resolution the name will be returned to the name resolution response message is the result of solving, characterized in that Method. A packet transfer device for transferring a received packet to another node,
A user information acquisition unit that acquires attribute information about the sender of the name resolution request message sent from the client to the name resolution server;
  The name resolution request message is received once, attribute information about the sender of the name resolution request message is acquired via the user information acquisition unit, and the name resolution request message with the attribute information added is sent to the name resolution server. A packet transfer device comprising a DNS proxy unit for transmission. Furthermore, a user information database storing the attribute information is provided as an internal element,
  The packet transfer apparatus according to claim 9, wherein attribute information relating to a user who is a sender of the name resolution request message is acquired from the user information database via the user information acquisition unit. The packet transfer apparatus according to claim 9, further comprising: acquiring the attribute information from an external database server including a user information database in which the attribute information is stored via the user information acquisition unit. 12. The packet transfer apparatus according to claim 11, wherein a name resolution request message is used in acquiring the attribute information from the external database server. 13. The packet transfer apparatus according to claim 11, wherein the external database server is a name resolution server installed outside. Furthermore, a user authentication unit for identifying and authenticating a user in a client connected to the own node;
  The user information update part which updates the content of the said user information database based on the attribute information regarding the said user obtained at the time of authentication, The any one of Claims 9-13 characterized by the above-mentioned. Packet transfer device. 15. The information acquisition unit according to claim 9, wherein the information acquisition unit acquires attribute information related to a sender of the name resolution request message based on a source address included in the name resolution request message. Packet transfer device. A packet transfer method in a packet transfer device for transferring a received packet to another node,
The name resolution request message transmitted from the client to the name resolution server is temporarily received, the attribute information about the sender of the name resolution request message is acquired, and the name resolution request message with the attribute information added is sent to the name resolution server. A packet transfer method characterized by transmitting. A packet forwarding device that forwards received packets to other nodes.
A user information acquisition unit that acquires attribute information about the sender of the name resolution request message sent from the client to the name resolution server;
  The name resolution request message is received once, attribute information about the sender of the name resolution request message is acquired via the user information acquisition unit, and the name resolution request message with the attribute information added is sent to the name resolution server. A packet transfer program that functions as a DNS proxy unit for transmission.